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Gordon Proctor - One of the best experts on this subject based on the ideXlab platform.
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intraoral duct ligation without inclusion of the Parasympathetic Nerve supply induces rat submandibular gland atrophy
International Journal of Experimental Pathology, 2006Co-Authors: S M Osailan, Gordon Proctor, Mark Mcgurk, Katherine L PatersonAbstract:The atrophic effect of ligating the main duct of the right submandibular gland was examined in rat using a novel intraoral approach that did not include the chorda lingual (CL) Nerve. Comparison was made with the effect of duct ligation including the attached CL Nerve as carried out in previous studies. In all animals, the contralateral, unligated left submandibular gland was used as a control. At different times (1, 2, 7, 14 and 21 days) after ligation, glands were removed and weighed. Tissue was fixed for morphological analysis and homogenized for biochemical assay of secretory proteins. After 21 days, ligated glands showed a significant decrease in wet weight compared with unligated glands. Weight loss was the greatest (P < 0.05) in glands ligated with the CL Nerve included. Light microscopy revealed that following ligation, an initial inflammatory reaction was followed by severe atrophy of acini and granular ducts. The atrophy was less severe when the CL Nerve was not ligated. Secretory proteins were decreased from day 1 onwards following duct ligation in both groups. It can be concluded that most of the atrophy induced by duct ligation is independent of damage caused to the Parasympathetic Nerve supply, although the latter causes a greater atrophy presumably due to denervation.
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immunoglobulin a secretion into saliva during dual sympathetic and Parasympathetic Nerve stimulation of rat submandibular glands
Experimental Physiology, 2000Co-Authors: Guy H Carpenter, Gordon Proctor, L C Anderson, X S Zhang, J R GarrettAbstract:Salivary secretion of proteins from rat submandibular glands was studied using graded stimulation of the Parasympathetic Nerve in isolation, and then at a fixed rate in combination with graded sympathetic Nerve stimulation. Increasing the frequency of Parasympathetic Nerve stimulation per se caused a gradual increase in the secretion of peroxidase (from acini) but only small increases in proteinase (from ductal cells) and IgA outputs. Dual stimulations, with an increasing frequency of sympathetic Nerve stimulation on a background of low frequency Parasympathetic Nerve stimulation, showed that maximal acinar secretion of peroxidase required only a low frequency of additional sympathetic stimulation, whereas ductal secretion of kallikrein was greatest with the highest frequency of additional sympathetic stimulation (20 Hz in bursts). IgA secretion also required high frequency additional sympathetic stimulation in bursts for greatest output. Although a synergism occurred with Parasympathetic plus sympathetic Nerve stimulation for the secretion of both peroxidase and kallikrein it was not evident for the secretion of IgA. This presumably reflects a difference for exocytosis of proteins stored in granules (e.g. peroxidase and kallikrein) compared to those proteins continuously transported across the plasma membrane in vesicles by transcytosis. This work confirms that vesicular movement of secretory IgA can be increased by both Parasympathetic and sympathetic Nerve stimulation, but the frequency parameters differ for each Nerve.
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protein secretion from rat submandibular acini and granular ducts effects of exogenous vip and substance p during Parasympathetic Nerve stimulation
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 1998Co-Authors: L C Anderson, J R Garrett, Xiaoshan Zhang, Gordon ProctorAbstract:Abstract The influences of exogenous vasoactive intestinal peptide (VIP) and substance P on the release of peroxidase from acini and true tissue kallikrein (rK1) from granular ducts of the rat submandibular gland were studied during continuous Parasympathetic stimulation. Parasympathetic Nerve impulses caused a moderate flow of saliva (mean ± SD , 108 ± 26 μ l/g tissue/min) that had a low protein concentration (174 ± 88 μ g/ml). The outputs of peroxidase and rK1 were minimal (14.3 ± 11.8 pmol DCF/g tissue/min and 6.5 ± 3.4 nmol AFC/g tissue/min, respectively). When administered intravenously, VIP had no apparent effect on the overall flow rate, but caused a significant increase in the output of peroxidase; 450% at 1 μ g/kg and a further 10-fold increase at 10 μ g/kg. In contrast, substance P (1 μ g/kg) evoked a marked increase in flow rate (68%), and peroxidase secretion increased only 3-fold. The output of rK1 was unaffected by either VIP or substance P. Our results support the hypothesis that acinar, but not granular duct, protein secretion is evoked by non-adrenergic, non-cholinergic peptides released from Parasympathetic Nerve terminals.
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in vivo secretory responses of submandibular glands in streptozotocin diabetic rats to sympathetic and Parasympathetic Nerve stimulation
Cell and Tissue Research, 1993Co-Authors: L C Anderson, Gordon Proctor, J R Garrett, Ahmed H Suleiman, Kaming Chan, R HartleyAbstract:Submandibular gland responses to sympathetic and Parasympathetic Nerve stimulation were studied in streptozotocin-diabetic rats. Morphologically, the acinar cells in control glands were relatively uniform in size and contained electron-lucent granules. The granular ducts were distinguished by the presence of electron-dense granules. With the exception of intracellular lipid droplets and the presence of a few autophagosomes in diabetic glands, no consistent differences in acinar cell structure were observed. In contrast, the diameter of the granular ducts and the granule content of their cells were less in diabetic glands. At 3 weeks sympathetic flow rate, salivary protein concentration, and total protein output were unaffected by diabetes. Sympathetic flow rate was greater at 3 months, and the concentration of protein in the saliva was lower. In 6-month diabetic rats flow rate remained increased, but protein concentration and total protein output were reduced. The decrease in salivary protein concentration at 3 and 6 months was accompanied by a reduction in secretory granule release from acinar and granular duct cells. No consistent differences in flow rate, protein concentration, protein output, or secretory granule release were observed following Parasympathetic stimulation. We conclude that the effects of diabetes on Nerve-stimulated flow rate and protein release depend on the duration of diabetes and the type of stimulation, and are independent of one another.
J R Garrett - One of the best experts on this subject based on the ideXlab platform.
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immunoglobulin a secretion into saliva during dual sympathetic and Parasympathetic Nerve stimulation of rat submandibular glands
Experimental Physiology, 2000Co-Authors: Guy H Carpenter, Gordon Proctor, L C Anderson, X S Zhang, J R GarrettAbstract:Salivary secretion of proteins from rat submandibular glands was studied using graded stimulation of the Parasympathetic Nerve in isolation, and then at a fixed rate in combination with graded sympathetic Nerve stimulation. Increasing the frequency of Parasympathetic Nerve stimulation per se caused a gradual increase in the secretion of peroxidase (from acini) but only small increases in proteinase (from ductal cells) and IgA outputs. Dual stimulations, with an increasing frequency of sympathetic Nerve stimulation on a background of low frequency Parasympathetic Nerve stimulation, showed that maximal acinar secretion of peroxidase required only a low frequency of additional sympathetic stimulation, whereas ductal secretion of kallikrein was greatest with the highest frequency of additional sympathetic stimulation (20 Hz in bursts). IgA secretion also required high frequency additional sympathetic stimulation in bursts for greatest output. Although a synergism occurred with Parasympathetic plus sympathetic Nerve stimulation for the secretion of both peroxidase and kallikrein it was not evident for the secretion of IgA. This presumably reflects a difference for exocytosis of proteins stored in granules (e.g. peroxidase and kallikrein) compared to those proteins continuously transported across the plasma membrane in vesicles by transcytosis. This work confirms that vesicular movement of secretory IgA can be increased by both Parasympathetic and sympathetic Nerve stimulation, but the frequency parameters differ for each Nerve.
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protein secretion from rat submandibular acini and granular ducts effects of exogenous vip and substance p during Parasympathetic Nerve stimulation
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 1998Co-Authors: L C Anderson, J R Garrett, Xiaoshan Zhang, Gordon ProctorAbstract:Abstract The influences of exogenous vasoactive intestinal peptide (VIP) and substance P on the release of peroxidase from acini and true tissue kallikrein (rK1) from granular ducts of the rat submandibular gland were studied during continuous Parasympathetic stimulation. Parasympathetic Nerve impulses caused a moderate flow of saliva (mean ± SD , 108 ± 26 μ l/g tissue/min) that had a low protein concentration (174 ± 88 μ g/ml). The outputs of peroxidase and rK1 were minimal (14.3 ± 11.8 pmol DCF/g tissue/min and 6.5 ± 3.4 nmol AFC/g tissue/min, respectively). When administered intravenously, VIP had no apparent effect on the overall flow rate, but caused a significant increase in the output of peroxidase; 450% at 1 μ g/kg and a further 10-fold increase at 10 μ g/kg. In contrast, substance P (1 μ g/kg) evoked a marked increase in flow rate (68%), and peroxidase secretion increased only 3-fold. The output of rK1 was unaffected by either VIP or substance P. Our results support the hypothesis that acinar, but not granular duct, protein secretion is evoked by non-adrenergic, non-cholinergic peptides released from Parasympathetic Nerve terminals.
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in vivo secretory responses of submandibular glands in streptozotocin diabetic rats to sympathetic and Parasympathetic Nerve stimulation
Cell and Tissue Research, 1993Co-Authors: L C Anderson, Gordon Proctor, J R Garrett, Ahmed H Suleiman, Kaming Chan, R HartleyAbstract:Submandibular gland responses to sympathetic and Parasympathetic Nerve stimulation were studied in streptozotocin-diabetic rats. Morphologically, the acinar cells in control glands were relatively uniform in size and contained electron-lucent granules. The granular ducts were distinguished by the presence of electron-dense granules. With the exception of intracellular lipid droplets and the presence of a few autophagosomes in diabetic glands, no consistent differences in acinar cell structure were observed. In contrast, the diameter of the granular ducts and the granule content of their cells were less in diabetic glands. At 3 weeks sympathetic flow rate, salivary protein concentration, and total protein output were unaffected by diabetes. Sympathetic flow rate was greater at 3 months, and the concentration of protein in the saliva was lower. In 6-month diabetic rats flow rate remained increased, but protein concentration and total protein output were reduced. The decrease in salivary protein concentration at 3 and 6 months was accompanied by a reduction in secretory granule release from acinar and granular duct cells. No consistent differences in flow rate, protein concentration, protein output, or secretory granule release were observed following Parasympathetic stimulation. We conclude that the effects of diabetes on Nerve-stimulated flow rate and protein release depend on the duration of diabetes and the type of stimulation, and are independent of one another.
L C Anderson - One of the best experts on this subject based on the ideXlab platform.
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immunoglobulin a secretion into saliva during dual sympathetic and Parasympathetic Nerve stimulation of rat submandibular glands
Experimental Physiology, 2000Co-Authors: Guy H Carpenter, Gordon Proctor, L C Anderson, X S Zhang, J R GarrettAbstract:Salivary secretion of proteins from rat submandibular glands was studied using graded stimulation of the Parasympathetic Nerve in isolation, and then at a fixed rate in combination with graded sympathetic Nerve stimulation. Increasing the frequency of Parasympathetic Nerve stimulation per se caused a gradual increase in the secretion of peroxidase (from acini) but only small increases in proteinase (from ductal cells) and IgA outputs. Dual stimulations, with an increasing frequency of sympathetic Nerve stimulation on a background of low frequency Parasympathetic Nerve stimulation, showed that maximal acinar secretion of peroxidase required only a low frequency of additional sympathetic stimulation, whereas ductal secretion of kallikrein was greatest with the highest frequency of additional sympathetic stimulation (20 Hz in bursts). IgA secretion also required high frequency additional sympathetic stimulation in bursts for greatest output. Although a synergism occurred with Parasympathetic plus sympathetic Nerve stimulation for the secretion of both peroxidase and kallikrein it was not evident for the secretion of IgA. This presumably reflects a difference for exocytosis of proteins stored in granules (e.g. peroxidase and kallikrein) compared to those proteins continuously transported across the plasma membrane in vesicles by transcytosis. This work confirms that vesicular movement of secretory IgA can be increased by both Parasympathetic and sympathetic Nerve stimulation, but the frequency parameters differ for each Nerve.
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protein secretion from rat submandibular acini and granular ducts effects of exogenous vip and substance p during Parasympathetic Nerve stimulation
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 1998Co-Authors: L C Anderson, J R Garrett, Xiaoshan Zhang, Gordon ProctorAbstract:Abstract The influences of exogenous vasoactive intestinal peptide (VIP) and substance P on the release of peroxidase from acini and true tissue kallikrein (rK1) from granular ducts of the rat submandibular gland were studied during continuous Parasympathetic stimulation. Parasympathetic Nerve impulses caused a moderate flow of saliva (mean ± SD , 108 ± 26 μ l/g tissue/min) that had a low protein concentration (174 ± 88 μ g/ml). The outputs of peroxidase and rK1 were minimal (14.3 ± 11.8 pmol DCF/g tissue/min and 6.5 ± 3.4 nmol AFC/g tissue/min, respectively). When administered intravenously, VIP had no apparent effect on the overall flow rate, but caused a significant increase in the output of peroxidase; 450% at 1 μ g/kg and a further 10-fold increase at 10 μ g/kg. In contrast, substance P (1 μ g/kg) evoked a marked increase in flow rate (68%), and peroxidase secretion increased only 3-fold. The output of rK1 was unaffected by either VIP or substance P. Our results support the hypothesis that acinar, but not granular duct, protein secretion is evoked by non-adrenergic, non-cholinergic peptides released from Parasympathetic Nerve terminals.
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in vivo secretory responses of submandibular glands in streptozotocin diabetic rats to sympathetic and Parasympathetic Nerve stimulation
Cell and Tissue Research, 1993Co-Authors: L C Anderson, Gordon Proctor, J R Garrett, Ahmed H Suleiman, Kaming Chan, R HartleyAbstract:Submandibular gland responses to sympathetic and Parasympathetic Nerve stimulation were studied in streptozotocin-diabetic rats. Morphologically, the acinar cells in control glands were relatively uniform in size and contained electron-lucent granules. The granular ducts were distinguished by the presence of electron-dense granules. With the exception of intracellular lipid droplets and the presence of a few autophagosomes in diabetic glands, no consistent differences in acinar cell structure were observed. In contrast, the diameter of the granular ducts and the granule content of their cells were less in diabetic glands. At 3 weeks sympathetic flow rate, salivary protein concentration, and total protein output were unaffected by diabetes. Sympathetic flow rate was greater at 3 months, and the concentration of protein in the saliva was lower. In 6-month diabetic rats flow rate remained increased, but protein concentration and total protein output were reduced. The decrease in salivary protein concentration at 3 and 6 months was accompanied by a reduction in secretory granule release from acinar and granular duct cells. No consistent differences in flow rate, protein concentration, protein output, or secretory granule release were observed following Parasympathetic stimulation. We conclude that the effects of diabetes on Nerve-stimulated flow rate and protein release depend on the duration of diabetes and the type of stimulation, and are independent of one another.
Kazuhiro Yamaguchi - One of the best experts on this subject based on the ideXlab platform.
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a novel method predicting Parasympathetic Nerve dysfunction in subjects with apneic events instantaneous time frequency analysis
Medical research archives, 2016Co-Authors: Kazuhiro Yamaguchi, Mizuha Haraguchi, Haruki Sekiguchi, Takao Tsuji, Kazutetsu Aoshiba, Atsushi NagaiAbstract:The pathophysiological aspects of Parasympathetic Nerve (PN) function during sleep in patients with morbid apneas/hypopneas studied by classical methods, including power-spectrum and/or time-domain analysis on heart rate variability (HRV), are highly controversial. This controversy is attributed to methodological problems such as poor time resolution in classical methods. In the present review, we describe a reliable method for investigating the PN function in patients with apneas/hypopneas, which has recently been elaborated and named “instantaneous time-frequency analysis (ITF)”. The ITF was established based on the complex demodulation (CD) algorism, which enables us to measure the transitional change in amplitude of a target frequency domain in a practically continuous manner. Among high frequency (HF) domains between 0.15 and 0.40 Hz contained in R-R intervals of electrocardiogram tracing (representative of HRV), the HF domain with the maximum amplitude was used as an approximate measure of PN activity. Based on density-spectrum-array map for main HF peak constructed with time scale of 1 sec and frequency resolution of 0.002 Hz (HF-DSA map), shift in central frequency of main HF peak over time was continuously monitored. When the main HF peak with the same central frequency lasted for more than 20 seconds or 5 minutes on HF-DSA map, the PN function was assumed “stable” or “very stable”, respectively. Based on the ITF, we elucidated the qualitative and quantitative abnormalities in PN function in patients with obstructive sleep apnea (OSA), while it was not possible to evaluate PN abnormalities in patients with central sleep apnea (CSA). Furthermore, we certified the effects of various confounding factors on PN function in OSA patients, i.e., PN activity was inhibited by aging and obesity, while PN stability was distorted by apneas/hypopneas. To establish the clinical importance of ITF, we also determined normal reference values regarding the activity and stability of PN function.
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gender specific impacts of apnea age and bmi on Parasympathetic Nerve dysfunction during sleep in patients with obstructive sleep apnea
PLOS ONE, 2014Co-Authors: Kazuhiro Yamaguchi, Haruki Sekiguchi, Takao Tsuji, Noboru Ohki, Natsumi Satoya, Yuji Inoue, Yoshiko Maeda, Mayumi Suzuki, Fukumi Inoue, Kazutetsu AoshibaAbstract:Background The gender-specific influences of various confounding factors, including apnea, age, BMI, and cigarette consumption, on the function of the Parasympathetic Nerve system (PNS) during sleep in OSA patients has never been investigated. Methods One hundred ninety-seven males and 63 females with OSA were subjected to full PSG examinations including assessment of R-R intervals (RRIs) during an overnight ECG. The PNS-derived modulatory effect on the RRIs and the variability of this effect were quantified during REM and NREM using instantaneous time-frequency analysis with complex demodulation. The spectral domain with the maximum instantaneous amplitude in the high-frequency band between 0.15 and 0.4 Hz was defined as the main HF peak and used as a surrogate marker of PNS discharge. Based on density-spectrum-array maps of the main HF peaks (HF-DSA map), shifts in the central frequency of the main HF peak over time were continuously observed. When the main HF peaks on the HF-DSA maps maintained the same central frequency for more than 20 sec or 5 min, the PNS functions were considered to be “stable” or “very stable”, respectively. Results Apneas enhanced PNS-derived cardiac-modulation during REM in males, but more importantly, they made PNS-function unstable during both REM and NREM in males and during NREM in females. Aging blunted the PNS-derived cardiac-modulation during both REM and NREM regardless of gender, but aging had no impact on the stability of PNS-function. BMI blunted PNS-eliciting cardiac-modulation during REM in males and during NREM in both males and females. BMI made the PNS unstable during REM in females. Neither height nor cigarette consumption influenced any PNS-related parameter. Conclusions The PNS-derived cardiac-modulation was generally inhibited by aging and obesity, in which the effect of obesity was gender-specific. The PNS instability at nighttime was mainly induced by apneas but by obesity particularly during REM in females.
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estimation of Parasympathetic Nerve function during sleep in patients with obstructive sleep apnea by instantaneous time frequency analysis
Sleep Medicine, 2014Co-Authors: Kazuhiro Yamaguchi, Haruki Sekiguchi, Noboru Ohki, Maiko Kobayashi, Natsumi Satoya, Yuji Inoue, Shigemitsu Onizawa, Yoshiko Maeda, Mayumi Suzuki, Takao TsujiAbstract:Abstract Background and objectives The pathophysiologic aspects of Parasympathetic Nerve (PN) function during sleep in patients with obstructive sleep apnea (OSA) studied by classical power spectrum analysis on heart rate variability (HRV) are highly controversial. The controversy is attributed to methodologic concerns, such as poor time resolution involved in power spectrum analysis. We aimed to establish the appropriate method for the investigation of PN function in OSA patients with apneas and hypopneas using instantaneous time–frequency analysis with complex demodulation (CD) and sufficient time resolution. Methods A total of 30 patients with PSG-confirmed mild to severe OSA were recruited for the analysis of frequency spectra contained in R-R intervals (RRI) of overnight electrocardiograph (ECG) tracings. High-frequency (HF) domains ranging between 0.15 and 0.40 Hz were selected for analysis. Among these domains, the HF domain with the maximum instantaneous amplitude was defined as the main HF peak and was used as the surrogate marker of PN discharge. Based on density spectrum array (DSA) map for main HF peak constructed with a time scale of 1 s and a frequency resolution of 0.002 Hz (HF-DSA map), the shift in central frequency (CF) of main HF peak over time was continuously monitored. When the main HF peak with the same CF lasted for more than 20 s or 5 min on HF-DSA map, the PN function was considered to be stable or very stable. The measurements were then repeated after continuous positive airway pressure (CPAP) treatment. Results The extent of PN-evoked modulation of RRI was enhanced in nonrapid eye movement (NREM) sleep, though the stability was reduced in both NREM and rapid eye movement (REM) sleep. These peculiar behaviors of PN function were reversed by CPAP treatment. Conclusion We found that instantaneous time–frequency analysis allowed estimation of transitional changes in PN function during sleep in OSA patients.
Toshihide Sato - One of the best experts on this subject based on the ideXlab platform.
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Enhancement of Gustatory Neural Responses by Parasympathetic Nerve in the Frog
Cellular and Molecular Neurobiology, 2018Co-Authors: Toshihide Sato, Yukio OkadaAbstract:The autonomic nervous system affects the gustatory responses in animals. Frog glossopharyngeal Nerve (GPN) contains the Parasympathetic Nerve. We checked the effects of electrical stimulation (ES) of the Parasympathetic Nerves on the gustatory neural responses. The gustatory neural impulses of the GPNs were recorded using bipolar AgCl wires under normal blood circulation and integrated with a time constant of 1 s. Electrical stimuli were applied to the proximal side of the GPN with a pair of AgCl wires. The Parasympathetic Nerves of the GPN were strongly stimulated for 10 s with 6 V at 30 Hz before taste stimulation. The integrated neural responses to 0.5 M NaCl, 2.5 mM CaCl_2, water, and 1 M sucrose were enhanced to 130–140% of the controls. On the other hand, the responses for 1 mM Q-HCl and 0.3 mM acetic acid were not changed by the preceding applied ES. After hexamethonium (a blocker of nicotinic ACh receptor) was intravenously injected, ES of the Parasympathetic Nerve did not modulate the responses for all six taste stimuli. The mechanism for enhancement of the gustatory neural responses is discussed.
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Tonic Activity of Parasympathetic Efferent Nerve Fibers Hyperpolarizes the Resting Membrane Potential of Frog Taste Cells
2014Co-Authors: Toshihide Sato, Yukio Okada, Kazuhisa Nishishita, Yuzo Kato, Kazuo TodaAbstract:We investigated the relationship between the membrane potential of frog taste cells in the fungiform papillae and the tonic discharge of Parasympathetic efferent fibers in the glossopharyngeal (GP) Nerve. When the Parasympathetic preganglionic fibers in the GP Nerve were kept intact, the mean membrane potential of Ringer-adapted taste cells was 40 mV but decreased to 31mVafter transecting the preganglionic fibers in theGPNerve and crushing the postganglionic fibers in the papillary Nerve. The same result occurred after blocking the nicotinic acetylcholine receptors on Parasympathetic ganglion cells in the tongue and blocking the substance P neurokinin-1 (NK-1) receptors in the gustatory efferent synapses. This indicates that the Parasympathetic Nerve (PSN) hyperpolarizes the membrane potential of frog taste cells by 9 mV. Repetitive stimulation of a transected GP Nerve revealed that a9-mV hyperpolarization of taste cells maintained under the intact GP Nerve derives from an;10-Hz discharge of the PSN efferent fibers. Themean frequency of tonic discharges extracellularly recorded from PSN efferent fibers of the taste disks was 9.1 impulses/s. We conclude that the resting membrane potential of frog taste cells is continuously hyperpolarized by on average 9 mV by an;10-Hz tonic discharge from the Parasympathetic preganglionic neurons in the medulla oblongata. Key words: gustatory efferent synapse, membrane potential, Parasympathetic Nerve, slow hyperpolarizing potential, taste receptor cel
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depression of gustatory receptor potential in frog taste cell by Parasympathetic Nerve induced slow hyperpolarizing potential
Chemical Senses, 2007Co-Authors: Toshihide Sato, Yukio Okada, Kazuhisa Nishishita, Takao Mineda, Kazuo TodaAbstract:Parasympathetic Nerve (PSN) innervates taste cells of the frog taste disk, and electrical stimulation of PSN elicited a slow hyperpolarizing potential (HP) in taste cells. Here we report that gustatory receptor potentials in frog taste cells are depressed by PSN-induced slow HPs. When PSN was stimulated at 30 Hz during generation of taste cell responses, the large amplitude of depolarizing receptor potential for 1 M NaCl and 1 mM acetic acid was depressed by ;40% by slow HPs, but the small amplitude of the depolarizing receptor potential for 10 mM quinine–HCl (Q-HCl) and 1 M sucrose was completely depressed by slow HPs and furthermore changed to the hyperpolarizing direction. The duration of the depolarizing receptor potentials depressed by slow HPs prolonged with increasing period of PSN stimulation. As tastant-induced depolarizing receptor potentials were increased, the amplitude of PSN-induced slow HPs inhibiting the receptor potentials gradually decreased. The mean reversal potentials of the slow HPs were approximately 1 mV under NaCl and acetic acid stimulations, but approximately 14 mV under Q-HCl and sucrose stimulations. This implies that when a slow HP was evoked on the same amplitude of depolarizing receptor potentials, the depression of the NaCl and acetic acid responses in taste cells was larger than that of Q-HCl and sucrose responses. It is concluded that slow HP–induced depression of gustatory depolarizing receptor potentials derives from the interaction between gustatory receptor current and slow hyperpolarizing current in frog taste cells and that the interaction is stronger for NaCl and acetic acid stimulations than for Q-HCl and sucrose stimulations.
