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Christopher L H Huang - One of the best experts on this subject based on the ideXlab platform.
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loop diuretics inhibit detubulation and vacuolation in amphibian muscle fibres exposed to osmotic shock
Journal of Muscle Research and Cell Motility, 2000Co-Authors: Kamron N Khan, Jeremy N Skepper, Austin R Hockaday, Anthony J Burgess, Christopher L H HuangAbstract:The effect of loop diuretics at concentrations known to influence cellular water entry coupled to Na-K-Cl co-transport, upon the vacuolation and detubulation following osmotic shock, was investigated in amphibian skeletal muscles. These were exposed to a glycerol-Ringer Solution (18 min), an isotonic Ca2+/Mg2+ Ringer Solution and cooling. Adding bumetanide (1.0 and 2.0 μM) to these Solutions sharply reduced the incidence of detubulation, assessed by abolition or otherwise of action potential after-depolarisations, from 93.9 ± 4.7% (n = 6) to 5.0 ± 1.1% (n = 4: mean ± SEM: 2.0 μM bumetanide). It dramatically reduced the number and fraction of muscle volume occupied by tubular vacuoles, measured using confocal microscopy, from 60.3 ± 4.3% (n = 10) to 9.0 ± 1.1% (n = 35). The incidence of large horseradish peroxidase-lined tubular vacuoles, viewed using electronmicroscopy, similarly was reduced with 2 μM bumetanide in the glycerol-Ringer Solution. Bumetanide acted through cellular volume adjustments early in the detubulation protocol. Thus, it exerted its maximum effect when added to the glycerol-Ringer, rather than the Ca2+/Mg2+ Ringer Solution. Furthermore, whereas fibre diameters measured using scanning electron microscopy returned to normal during glycerol treatment relative to those of control fibres left in isotonic Ringer, addition of 2.0 μM bumetanide in the glycerol Ringer left markedly smaller fibre diameters. Finally equipotent concentrations of the chemically distinct loop diuretics, furosemide and ethacrynic acid similarly influenced detubulation. These findings implicate Na-K-Cl co-transport in the water entry into muscle fibres that would be expected following introduction of extracellular glycerol. This might then enable the subsequent Na-K-ATPase dependent water extrusion that produces the tubular distension (vacuolation) and detachment (detubulation) following glycerol withdrawal, phenomena also observed in muscular dystrophy.
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the afterdepolarization in rana temporaria muscle fibres following osmotic shock
Journal of Muscle Research and Cell Motility, 1995Co-Authors: George Koutsis, Alexander Philippides, Christopher L H HuangAbstract:Rana temporaria sartorius muscle fibres were exposed to varied sequences of Solution and temperature changes that have been employed hitherto in procedures that sought to decouple the transverse tubules from the surface membrane. The incidence of such detubulation was assessed in large numbers of fibres through demonstrating a loss or otherwise of the after-depolarization that normally reflects successful tubular propagation of the surface action potential. This criterion yielded assessments of the existing detubulation techniques in agreement with earlier results. The experiments then developed an improved detubulation procedure that required only brief (15 min) exposures to glycerol, its replacement in a single step by a Ca2+/Mg(2+)-Ringer Solution for 30 min, and rapid cooling from room temperature (19-21 degrees C) to 6-10 degrees C prior to final restoration of the normal Ringer Solution. This sequence of steps yielded an optimal incidence (98%) of detubulation in viable surface fibres that were amenable to electrophysiological studies. Studies that systematically modified the detubulation procedure demonstrated that the omission of any one step in the protocol significantly reduced the incidence of detubulation with or without accompanying deteriorations in fibre resting potentials. Successful detubulation accordingly required an initial exposure to an optimal glycerol concentration that lasted for a minimal duration and for its abrupt withdrawal. Inclusion of a cooling step within 30 min after glycerol withdrawal was coincident with, and critical to, optimal tubular isolation. Thus, cooling steps that either preceded, or that followed the glycerol withdrawal step by more than 60 min, resulted in a sharp reduction in the incidence of detubulation. Similarly, a critical period of exposure to Ca2+/Mg2+ Ringer Solution also promoted detubulation without compromising the recovery of stable and satisfactory resting potentials. The findings reported here remain consistent with a primarily osmotic mechanism for detubulation. However, they demonstrated additional and important influences of temperature and of divalent cation concentration on the extent of tubular detachment when such factors were modified during the time course of the expected volume changes that followed each adjustment in osmotic condition.
Hiromi Ohta - One of the best experts on this subject based on the ideXlab platform.
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effects of cryopreservation methods on post thaw motility of spermatozoa from the japanese pearl oyster pinctada fucata martensii
Cryobiology, 2007Co-Authors: Takayuki Kawamoto, Teruyoshi Narita, Kiyoshi Isowa, Hideo Aoki, Masahiro Hayashi, Akira Komaru, Hiromi OhtaAbstract:Abstract In order to develop cryopreservation techniques for Japanese pearl oyster spermatozoa, the effects of various cryopreservation conditions on post-thaw motility were examined. Spermatozoa cryopreserved with 10% methanol (MET), dimethylformamide or dimethylacetamide plus 90% diluent comprising 80% seawater and 20% fetal bovine serum (FBS) showed higher percentages of post-thaw motility than those cryopreserved with 10% dimethylsulfoxide or glycerol. When spermatozoa were cryopreserved with various concentrations (0–20%) of MET and 100–80% diluent, 10% MET showed the highest percentages of post-thaw motility. When spermatozoa were cryopreserved with 10% MET and 90% diluent comprising various concentrations (0–100%) of FBS or Ringer Solution mixed with seawater, the percentages of post-thaw motility peaked at 20% FBS or Ringer Solution, and were significantly higher for 20% FBS than for 20% Ringer Solution. The percentages of post-thaw motility increased with increasing dilution ratios from 2.5- to 50-fold. Spermatozoa cooled to −50 °C and then immersed in liquid nitrogen (LN) showed higher post-thaw motility than those cooled to −30 °C or −40 °C. When spermatozoa were cryopreserved to −50 °C at various cooling rates by changing the sample height above the LN surface, the post-thaw motilities of spermatozoa cooled at 10 cm (cooling rate: −21.3 °C/min) and 12.5 cm (−15.6 °C/min) from the LN surface were higher than those at 5, 7.5 or 15 cm. These results indicate that 10% MET plus 90% diluent comprising 80% seawater and 20% FBS is a suitable extender for cryopreservation of Japanese pearl oyster spermatozoa and that samples should be cooled to −50 °C at a cooling rate between −15 and −20 °C/min for efficient storage.
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effects of cryopreservation methods on post thaw motility of spermatozoa from the japanese pearl oyster pinctada fucata martensii
Cryobiology, 2007Co-Authors: Takayuki Kawamoto, Teruyoshi Narita, Kiyoshi Isowa, Hideo Aoki, Masahiro Hayashi, Akira Komaru, Hiromi OhtaAbstract:In order to develop cryopreservation techniques for Japanese pearl oyster spermatozoa, the effects of various cryopreservation conditions on post-thaw motility were examined. Spermatozoa cryopreserved with 10% methanol (MET), dimethylformamide or dimethylacetamide plus 90% diluent comprising 80% seawater and 20% fetal bovine serum (FBS) showed higher percentages of post-thaw motility than those cryopreserved with 10% dimethylsulfoxide or glycerol. When spermatozoa were cryopreserved with various concentrations (0-20%) of MET and 100-80% diluent, 10% MET showed the highest percentages of post-thaw motility. When spermatozoa were cryopreserved with 10% MET and 90% diluent comprising various concentrations (0-100%) of FBS or Ringer Solution mixed with seawater, the percentages of post-thaw motility peaked at 20% FBS or Ringer Solution, and were significantly higher for 20% FBS than for 20% Ringer Solution. The percentages of post-thaw motility increased with increasing dilution ratios from 2.5- to 50-fold. Spermatozoa cooled to -50 degrees C and then immersed in liquid nitrogen (LN) showed higher post-thaw motility than those cooled to -30 degrees C or -40 degrees C. When spermatozoa were cryopreserved to -50 degrees C at various cooling rates by changing the sample height above the LN surface, the post-thaw motilities of spermatozoa cooled at 10 cm (cooling rate: -21.3 degrees C/min) and 12.5 cm (-15.6 degrees C/min) from the LN surface were higher than those at 5, 7.5 or 15 cm. These results indicate that 10% MET plus 90% diluent comprising 80% seawater and 20% FBS is a suitable extender for cryopreservation of Japanese pearl oyster spermatozoa and that samples should be cooled to -50 degrees C at a cooling rate between -15 and -20 degrees C/min for efficient storage.
Glen P Kenny - One of the best experts on this subject based on the ideXlab platform.
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kca and kv channels modulate the venoarteriolar reflex in non glabrous human skin with no roles of katp channels nos and cox
European Journal of Pharmacology, 2020Co-Authors: Naoto Fujii, Gregory W Mcgarr, Masashi Ichinose, Takeshi Nishiyasu, Brendan D Mcneely, Glen P KennyAbstract:Abstract The venoarteriolar reflex is a local mechanism that induces vasoconstriction during venous congestion in various tissues, including skin. This response is thought to play a critical role in minimizing capillary damage or edema resulting from overperfusion, though factors that modulate this response remain largely unknown. Here, we hypothesized that nitric oxide synthase (NOS), cyclooxygenase (COX), and Ca2+-activated, ATP-sensitive, and voltage-gated K+ channels (KCa, KATP, and KV channels, respectively) modulate the venoarteriolar reflex in human skin. Cutaneous blood flow (laser-Doppler flowmetry) was monitored during a 3-min pre-occlusion baseline and following a 3-min venous occlusion of 45 mmHg, the latter maneuver was used to induce the venoarteriolar reflex. The venoarteriolar reflex was assessed at the following forearm skin sites: Experiment 1 (n = 11): 1) lactated Ringer Solution (Control), 2) 10 mM Nω-nitro-L-arginine (NOS inhibitor), 3) 10 mM ketorolac (COX inhibitor), and 4) combined NOS + COX inhibition; Experiment 2 (n = 15): 1) lactated Ringer Solution (Control), 2) 50 mM tetraethylammonium (KCa channel blocker), 3) 5 mM glybenclamide (KATP channel blocker), and 4) 10 mM 4-aminopyridine (KV channel blocker). Separate and combined NOS and COX inhibition as well as KATP channel blocker had no effect on venoarteriolar reflex. Conversely, venoarteriolar reflex was attenuated by KCa channel blockade (36–38%) and augmented by KV channel blockade (38–55%). We showed that KCa and KV channels modulate the venoarteriolar reflex with minimum roles of NOS, COX, and KATP channels in human non-glabrous forearm skin in vivo. Thus, cutaneous venoarteriolar reflex changes could reflect altered K+ channel function.
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tetraethylammonium glibenclamide and 4 aminopyridine modulate post occlusive reactive hyperemia in non glabrous human skin with no roles of nos and cox
Microcirculation, 2020Co-Authors: Naoto Fujii, Gregory W Mcgarr, Masashi Ichinose, Takeshi Nishiyasu, Glen P KennyAbstract:OBJECTIVES: Post-occlusive reactive hyperemia (PORH) following arterial occlusion is widely used to assess cutaneous microvascular function, though the underlying mechanisms remain to be fully elucidated. We evaluated the hypothesis that Ca(2+) -activated, ATP-sensitive, and voltage-gated K(+) channels (KC a , KATP , and KV channels, respectively) contribute to PORH while nitric oxide synthase (NOS) and cyclooxygenase (COX) do not. METHODS: On separate occasions, cutaneous blood flow (laser Doppler flowmetry) was monitored before and following 5-min arterial occlusion at forearm skin sites treated via microdialysis with the following: Experiment 1 (n = 11): (a) lactated Ringer Solution (Control), (b) 10 mM N(omega) -nitro-L -arginine (NOS inhibitor), (c) 10 mM ketorolac (COX inhibitor), and (d) combined NOS+COX inhibition; Experiment 2 (n = 14): (a) lactated Ringer Solution (Control), (b) 50 mM tetraethylammonium (non-selective KC a channel blocker), (c) 5 mM glibenclamide (non-specific KATP channel blocker), and (d) 10 mM 4-aminopyridine (non-selective KV channel blocker). RESULTS: Separate and combined NOS and COX inhibition did not influence PORH. Conversely, tetraethylammonium and glibenclamide attenuated, whereas 4-aminopyridine augmented PORH. CONCLUSIONS: We showed that tetraethylammonium, glibenclamide, and 4-aminopyridine modulate PORH with no roles of NOS and COX in human non-glabrous forearm skin in vivo. Thus, cutaneous PORH changes could reflect altered K(+) channel function.
Fang Liu - One of the best experts on this subject based on the ideXlab platform.
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the influence of lactate Ringer Solution versus hydroxyethyl starch on coagulation and fibrinolytic system in patients with septic shock
Chinese critical care medicine, 2012Co-Authors: Huiying Zhao, Fang LiuAbstract:Objective To investigate the influence of lactate Ringer Solution (RL) versus hydroxyethyl starch 130/0.4 (HES130/0.4) Solution on coagulation and fibrinolytic system in the patients with septic shock.Methods Forty-two consecutive patients with septic shock diagnosed between September 2009 and June 2011 were randomized to two study groups: RL resuscitation group (RL group) with 20 patients,and HES130/0.4 resuscitation group (HES group) with 22 patients.In all of them peripheral blood was collected at four points of time: before resuscitation,6,12,24 hours after resuscitation,and then prothrombin time (PT),activated partial thromboplastin time (APIT) and levels of plasma tissue plasminogen activator (t-PA),and plasminogen activator inhibitor (PAI) were determined.Meanwhile,the patients' outcome and the length of intensive care unit stay (ICU-LOS) were recorded.Results ICU-LOS (days) in HES group was significantly shorter than the RL group (12.5 ± 8.8 vs.17.1 + 16.6,P＜0.01 ).Meanwhile,the volume of fluid (L: 2.77 ± 0.59) as well as vasoactive drugs (μg· kg-1· min-1: 0.56 + 0.15 ) used in the HES group were significantly lower than RL group (3.46 ±0.73,0.81 +0.41,both P＜0.01 ).In RL group,12 patients died and 8 patients survived,while in HES group,7 patients died and 15 patients survived,showing no difference between two groups.PT,APTT and the levels of t-PA showed no significant differences between two groups at different time points, but the levels of plasma PAI (μg/L) of the HES group decreased gradually,and was significantly lower than that before resuscitation and RL group at 24 hours after resuscitation (41.76 ± 25.95 vs.89.11 + 14.27,55.08 ± 35.43,both P＜0.05 ).Conclusions Both RL and HES 130/0.4 fluid resuscitation did not affect the outcome of the patients with septic shock,but the resuscitation efficiency of HES130/0.4 is much better than RL.Both type of fluids did not show the effect on coagulability of the septic patients,but colloid fluid resuscitation may protect the vascular endothelial cell,reduce the inhibition of fibrinolytic system,and alleviate hypercoagulability state of patients in early stage. Key words: Septic shock; Lactate Ringer Solution; Hydroxyethyl starch; Coagulation; Fibrinolysis
J A Jansen - One of the best experts on this subject based on the ideXlab platform.
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a new method to produce macropores in calcium phosphate cements
Biomaterials, 2002Co-Authors: R P Del Real, J G C Wolke, Maria Valletregi, J A JansenAbstract:A new way to create macropores in calcium phosphate cements has been developed. The method consists in adding NaHCO3 to the starting cement powder (Biocement D) and using two different liquids: first a basic liquid to form the paste and later an acid liquid to obtain CO2 bubbles. Mercury intrusion measurements showed a dramatic increase both in macropores with an average size of 100 m and in the total porosity (even higher than 50% with respect to the Biocement D). This method does not change in any significant way the final reaction products of the starting material after being soaked 3 days in Ringer Solution. Only, due to the increase of the porosity. the compressive strength of the porous cement decreases significantly.
