The Experts below are selected from a list of 7353 Experts worldwide ranked by ideXlab platform
Ciriaco Carru - One of the best experts on this subject based on the ideXlab platform.
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simultaneous determination of aromatic amino acids in human blood plasma by capillary electrophoresis with uv absorption detection
IEEE Journal of Solid-state Circuits, 2015Co-Authors: Mauro Forteschi, Angelo Zinellu, Salvatore Sotgia, Stefano Assaretti, Dionigia Arru, Debora Cambedda, Elisabetta Sotgiu, Ciriaco CarruAbstract:Phenylalanine, tyrosine, and tryptophan, also known as aromatic amino acids, are involved in many physiological and pathophysiological conditions and are indicative of the liver and kidney function. In this work, we describe a simple and accurate method for their simultaneous quantification, in a single capillary electrophoresis run. This method requires minimal sample manipulation, no derivatization procedures, and methyl tryptophan as internal standard. The human blood plasma sample was precipitated using sulfosalicylic acid and the supernatant was used for the analysis. All the analytes were baseline resolved within 16 min and detected at 200 nm using Tris Phosphate 80 mmol/L at pH 1.4 as the background electrolyte. The proposed method showed good linearity (r = 0.998) and repeatability (intra-assay RSD < 2.78%, interassay RSD < 5.4%) for all the analytes. The limit of quantification was 13 μmol/L for phenylalanine and 5 μmol/L for tyrosine and tryptophan. The method suitability was tested measuring aromatic amino acids level in 20 chronic kidney disease patients at basal level and after simvastatin/ezetimibe treatment.
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simultaneous determination of citrulline and arginine in human blood plasma by capillary electrophoresis with ultraviolet absorption detection
IEEE Journal of Solid-state Circuits, 2014Co-Authors: Mauro Forteschi, Angelo Zinellu, Salvatore Sotgia, Gianfranco Pintus, Ciriaco CarruAbstract:A new capillary electrophoresis method to measure human blood plasma arginine and citrulline levels in a single run without derivatization was established. After adding homoarginine as internal standard, plasma proteins were removed by a 90:10 v/v acetonitrile/ammonia mixture. Arginine and citrulline were detected by an ultraviolet detector at 190 nm and separated in 11.65 and 20.43 min, respectively, by using a 75 mmol/L Tris Phosphate solution at pH 1.2 as a background electrolyte. Limits of detection were 0.8 and 5 μmol/L for arginine and citrulline, respectively. Precision tests indicated a good repeatability of migration times and of peak area both for citrulline (CV% = 0.82 and 3.19) and arginine (CV% = 0.65 and 2.79). The CV% for intra- and interassay tests were, respectively, 1.84 and 3.23 for citrulline and 1.25 and 1.50 for arginine. Mean recovery was 101.5 and 98.5% for citrulline and arginine, respectively. The performance of the developed method was assessed by measuring plasma arginine levels in 52 subjects and the data were compared with those obtained by our previous assay. The new method was then applied to assess plasma citrulline and arginine in ten chronic kidney disease patients under hypolipidemic therapy with statin.
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measurement of carnosine homocarnosine and anserine by fasi capillary electrophoresis uv detection applications on biological samples
Talanta, 2011Co-Authors: Angelo Zinellu, Salvatore Sotgia, Ilaria Campesi, Flavia Franconi, Luca Deiana, Ciriaco CarruAbstract:Abstract A field amplified sample injection (FASI) capillary electrophoresis method with UV detection was developed for the separation and detection of carnosine-related peptides carnosine (Car), anserine (Ans) and homocarnosine (Hcar). The imidazole dipeptides were baseline-separated within 10 min by using 50 mmol/L Tris Phosphate pH 2.2 as running buffer. The samples were diluted in water and directly injected on the capillary without complex cleanup and/or sample derivatization procedures. Using the electrokinetic injection, a sensitivity improvement of about 500-fold was achieved without any loss of separation efficiency if compared to the conventional sample injection. The detection limits for carnosine, anserine, and homocarnosine were between 0.4 and 0.5 nmol/L, thus improving of 10–100-fold the LOD of previous described methods based on laser induced fluorescence or chemiluminescence detection. This method has been applied to the analysis of homogenized rat tissue (heart, muscle and brain) and human cerebrospinal fluid (CSF).
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determination of homocysteine thiolactone reduced homocysteine homocystine homocysteine cysteine mixed disulfide cysteine and cystine in a reaction mixture by overimposed pressure voltage capillary electrophoresis
Talanta, 2010Co-Authors: Angelo Zinellu, Bastianina Scanu, Manuela Sanna, Shantanu Sengupta, Satish Sati, Elisabetta Pisanu, Salvatore Sotgia, Luca Deiana, Ciriaco CarruAbstract:An elevated level of thiol amino acid homocysteine is associated with several complex disorders. Homocysteine ability to bind proteins, thereby modulating their structure and function, is proposed to be one of the mechanisms of homocysteine induced pathogenecity. Homocysteine and homocysteine thiolactone bind to protein cysteine and lysine residues respectively. A major hurdle in studying protein homocysteinylation is the lack of suitable analytical techniques to determine simultaneously the concentrations of reduced and oxidized forms of homocysteine and cysteine (especially homocysteine–cysteine mixed disulfide) together with thiolactone formed during the reaction of homocysteine or thiolactone with proteins. Herein we report a capillary electrophoresis method to determine simultaneously the levels of these intermediates. For this 40 mmol/L Tris Phosphate buffer at (pH 1.60) was used as running electrolyte, and the separation was performed by the simultaneous application of a CE voltage of 15 kV and an overimposed pressure of 0.1 psi. A rapid separation of these intermediates in less than 6 min with a good reproducibility of both peak areas (CV < 2%) and migration time (CV < 0.2%) was obtained. The applicability of our method was validated by incubating reduced homocysteine and albumin and measuring the reaction intermediates in the solution mixture.
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assay for the simultaneous determination of guanidinoacetic acid creatinine and creatine in plasma and urine by capillary electrophoresis uv detection
Journal of Separation Science, 2006Co-Authors: Angelo Zinellu, Salvatore Sotgia, Luca Deiana, Elisabetta Zinellu, Roberto Chessa, Ciriaco CarruAbstract:Guanidinoacetic acid (GAA) measurement has recently become of great interest for the diagnosis of creatine (Cn) metabolism disorders, and research calls for rapid and inexpensive methods for its detection in plasma and urine in order to assess a large number of patients. We propose a new assay for the measurement of GAA by a simple CZE UV-detection without previous sample derivatization. Plasma samples were filtered by Microcon-10 microconcentrators and directly injected into the capillary, while for urine specimens a simple water dilution before injection was needed. A baseline separation was obtained in less than 8 min using a 60.2 cm x 75 microm uncoated silica capillary, 75 mmol/L Tris-Phosphate buffer pH 2.25 at 15 degrees C. The performance of the developed method was assessed by measuring plasma creatinine and Cn in 32 normal subjects and comparing the data obtained by the new method with those found with the previous CE assay. Our new method seems to be an inexpensive, fast and specific tool to assess a large number of patients both in clinical and in research laboratories.
Salvatore Sotgia - One of the best experts on this subject based on the ideXlab platform.
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simultaneous determination of aromatic amino acids in human blood plasma by capillary electrophoresis with uv absorption detection
IEEE Journal of Solid-state Circuits, 2015Co-Authors: Mauro Forteschi, Angelo Zinellu, Salvatore Sotgia, Stefano Assaretti, Dionigia Arru, Debora Cambedda, Elisabetta Sotgiu, Ciriaco CarruAbstract:Phenylalanine, tyrosine, and tryptophan, also known as aromatic amino acids, are involved in many physiological and pathophysiological conditions and are indicative of the liver and kidney function. In this work, we describe a simple and accurate method for their simultaneous quantification, in a single capillary electrophoresis run. This method requires minimal sample manipulation, no derivatization procedures, and methyl tryptophan as internal standard. The human blood plasma sample was precipitated using sulfosalicylic acid and the supernatant was used for the analysis. All the analytes were baseline resolved within 16 min and detected at 200 nm using Tris Phosphate 80 mmol/L at pH 1.4 as the background electrolyte. The proposed method showed good linearity (r = 0.998) and repeatability (intra-assay RSD < 2.78%, interassay RSD < 5.4%) for all the analytes. The limit of quantification was 13 μmol/L for phenylalanine and 5 μmol/L for tyrosine and tryptophan. The method suitability was tested measuring aromatic amino acids level in 20 chronic kidney disease patients at basal level and after simvastatin/ezetimibe treatment.
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simultaneous determination of citrulline and arginine in human blood plasma by capillary electrophoresis with ultraviolet absorption detection
IEEE Journal of Solid-state Circuits, 2014Co-Authors: Mauro Forteschi, Angelo Zinellu, Salvatore Sotgia, Gianfranco Pintus, Ciriaco CarruAbstract:A new capillary electrophoresis method to measure human blood plasma arginine and citrulline levels in a single run without derivatization was established. After adding homoarginine as internal standard, plasma proteins were removed by a 90:10 v/v acetonitrile/ammonia mixture. Arginine and citrulline were detected by an ultraviolet detector at 190 nm and separated in 11.65 and 20.43 min, respectively, by using a 75 mmol/L Tris Phosphate solution at pH 1.2 as a background electrolyte. Limits of detection were 0.8 and 5 μmol/L for arginine and citrulline, respectively. Precision tests indicated a good repeatability of migration times and of peak area both for citrulline (CV% = 0.82 and 3.19) and arginine (CV% = 0.65 and 2.79). The CV% for intra- and interassay tests were, respectively, 1.84 and 3.23 for citrulline and 1.25 and 1.50 for arginine. Mean recovery was 101.5 and 98.5% for citrulline and arginine, respectively. The performance of the developed method was assessed by measuring plasma arginine levels in 52 subjects and the data were compared with those obtained by our previous assay. The new method was then applied to assess plasma citrulline and arginine in ten chronic kidney disease patients under hypolipidemic therapy with statin.
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measurement of carnosine homocarnosine and anserine by fasi capillary electrophoresis uv detection applications on biological samples
Talanta, 2011Co-Authors: Angelo Zinellu, Salvatore Sotgia, Ilaria Campesi, Flavia Franconi, Luca Deiana, Ciriaco CarruAbstract:Abstract A field amplified sample injection (FASI) capillary electrophoresis method with UV detection was developed for the separation and detection of carnosine-related peptides carnosine (Car), anserine (Ans) and homocarnosine (Hcar). The imidazole dipeptides were baseline-separated within 10 min by using 50 mmol/L Tris Phosphate pH 2.2 as running buffer. The samples were diluted in water and directly injected on the capillary without complex cleanup and/or sample derivatization procedures. Using the electrokinetic injection, a sensitivity improvement of about 500-fold was achieved without any loss of separation efficiency if compared to the conventional sample injection. The detection limits for carnosine, anserine, and homocarnosine were between 0.4 and 0.5 nmol/L, thus improving of 10–100-fold the LOD of previous described methods based on laser induced fluorescence or chemiluminescence detection. This method has been applied to the analysis of homogenized rat tissue (heart, muscle and brain) and human cerebrospinal fluid (CSF).
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determination of homocysteine thiolactone reduced homocysteine homocystine homocysteine cysteine mixed disulfide cysteine and cystine in a reaction mixture by overimposed pressure voltage capillary electrophoresis
Talanta, 2010Co-Authors: Angelo Zinellu, Bastianina Scanu, Manuela Sanna, Shantanu Sengupta, Satish Sati, Elisabetta Pisanu, Salvatore Sotgia, Luca Deiana, Ciriaco CarruAbstract:An elevated level of thiol amino acid homocysteine is associated with several complex disorders. Homocysteine ability to bind proteins, thereby modulating their structure and function, is proposed to be one of the mechanisms of homocysteine induced pathogenecity. Homocysteine and homocysteine thiolactone bind to protein cysteine and lysine residues respectively. A major hurdle in studying protein homocysteinylation is the lack of suitable analytical techniques to determine simultaneously the concentrations of reduced and oxidized forms of homocysteine and cysteine (especially homocysteine–cysteine mixed disulfide) together with thiolactone formed during the reaction of homocysteine or thiolactone with proteins. Herein we report a capillary electrophoresis method to determine simultaneously the levels of these intermediates. For this 40 mmol/L Tris Phosphate buffer at (pH 1.60) was used as running electrolyte, and the separation was performed by the simultaneous application of a CE voltage of 15 kV and an overimposed pressure of 0.1 psi. A rapid separation of these intermediates in less than 6 min with a good reproducibility of both peak areas (CV < 2%) and migration time (CV < 0.2%) was obtained. The applicability of our method was validated by incubating reduced homocysteine and albumin and measuring the reaction intermediates in the solution mixture.
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assay for the simultaneous determination of guanidinoacetic acid creatinine and creatine in plasma and urine by capillary electrophoresis uv detection
Journal of Separation Science, 2006Co-Authors: Angelo Zinellu, Salvatore Sotgia, Luca Deiana, Elisabetta Zinellu, Roberto Chessa, Ciriaco CarruAbstract:Guanidinoacetic acid (GAA) measurement has recently become of great interest for the diagnosis of creatine (Cn) metabolism disorders, and research calls for rapid and inexpensive methods for its detection in plasma and urine in order to assess a large number of patients. We propose a new assay for the measurement of GAA by a simple CZE UV-detection without previous sample derivatization. Plasma samples were filtered by Microcon-10 microconcentrators and directly injected into the capillary, while for urine specimens a simple water dilution before injection was needed. A baseline separation was obtained in less than 8 min using a 60.2 cm x 75 microm uncoated silica capillary, 75 mmol/L Tris-Phosphate buffer pH 2.25 at 15 degrees C. The performance of the developed method was assessed by measuring plasma creatinine and Cn in 32 normal subjects and comparing the data obtained by the new method with those found with the previous CE assay. Our new method seems to be an inexpensive, fast and specific tool to assess a large number of patients both in clinical and in research laboratories.
Angelo Zinellu - One of the best experts on this subject based on the ideXlab platform.
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simultaneous determination of aromatic amino acids in human blood plasma by capillary electrophoresis with uv absorption detection
IEEE Journal of Solid-state Circuits, 2015Co-Authors: Mauro Forteschi, Angelo Zinellu, Salvatore Sotgia, Stefano Assaretti, Dionigia Arru, Debora Cambedda, Elisabetta Sotgiu, Ciriaco CarruAbstract:Phenylalanine, tyrosine, and tryptophan, also known as aromatic amino acids, are involved in many physiological and pathophysiological conditions and are indicative of the liver and kidney function. In this work, we describe a simple and accurate method for their simultaneous quantification, in a single capillary electrophoresis run. This method requires minimal sample manipulation, no derivatization procedures, and methyl tryptophan as internal standard. The human blood plasma sample was precipitated using sulfosalicylic acid and the supernatant was used for the analysis. All the analytes were baseline resolved within 16 min and detected at 200 nm using Tris Phosphate 80 mmol/L at pH 1.4 as the background electrolyte. The proposed method showed good linearity (r = 0.998) and repeatability (intra-assay RSD < 2.78%, interassay RSD < 5.4%) for all the analytes. The limit of quantification was 13 μmol/L for phenylalanine and 5 μmol/L for tyrosine and tryptophan. The method suitability was tested measuring aromatic amino acids level in 20 chronic kidney disease patients at basal level and after simvastatin/ezetimibe treatment.
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simultaneous determination of citrulline and arginine in human blood plasma by capillary electrophoresis with ultraviolet absorption detection
IEEE Journal of Solid-state Circuits, 2014Co-Authors: Mauro Forteschi, Angelo Zinellu, Salvatore Sotgia, Gianfranco Pintus, Ciriaco CarruAbstract:A new capillary electrophoresis method to measure human blood plasma arginine and citrulline levels in a single run without derivatization was established. After adding homoarginine as internal standard, plasma proteins were removed by a 90:10 v/v acetonitrile/ammonia mixture. Arginine and citrulline were detected by an ultraviolet detector at 190 nm and separated in 11.65 and 20.43 min, respectively, by using a 75 mmol/L Tris Phosphate solution at pH 1.2 as a background electrolyte. Limits of detection were 0.8 and 5 μmol/L for arginine and citrulline, respectively. Precision tests indicated a good repeatability of migration times and of peak area both for citrulline (CV% = 0.82 and 3.19) and arginine (CV% = 0.65 and 2.79). The CV% for intra- and interassay tests were, respectively, 1.84 and 3.23 for citrulline and 1.25 and 1.50 for arginine. Mean recovery was 101.5 and 98.5% for citrulline and arginine, respectively. The performance of the developed method was assessed by measuring plasma arginine levels in 52 subjects and the data were compared with those obtained by our previous assay. The new method was then applied to assess plasma citrulline and arginine in ten chronic kidney disease patients under hypolipidemic therapy with statin.
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determination of homocysteine thiolactone reduced homocysteine homocystine homocysteine cysteine mixed disulfide cysteine and cystine in a reaction mixture by overimposed pressure voltage capillary electrophoresis
Talanta, 2010Co-Authors: Angelo Zinellu, Bastianina Scanu, Manuela Sanna, Shantanu Sengupta, Satish Sati, Elisabetta Pisanu, Salvatore Sotgia, Luca Deiana, Ciriaco CarruAbstract:An elevated level of thiol amino acid homocysteine is associated with several complex disorders. Homocysteine ability to bind proteins, thereby modulating their structure and function, is proposed to be one of the mechanisms of homocysteine induced pathogenecity. Homocysteine and homocysteine thiolactone bind to protein cysteine and lysine residues respectively. A major hurdle in studying protein homocysteinylation is the lack of suitable analytical techniques to determine simultaneously the concentrations of reduced and oxidized forms of homocysteine and cysteine (especially homocysteine–cysteine mixed disulfide) together with thiolactone formed during the reaction of homocysteine or thiolactone with proteins. Herein we report a capillary electrophoresis method to determine simultaneously the levels of these intermediates. For this 40 mmol/L Tris Phosphate buffer at (pH 1.60) was used as running electrolyte, and the separation was performed by the simultaneous application of a CE voltage of 15 kV and an overimposed pressure of 0.1 psi. A rapid separation of these intermediates in less than 6 min with a good reproducibility of both peak areas (CV < 2%) and migration time (CV < 0.2%) was obtained. The applicability of our method was validated by incubating reduced homocysteine and albumin and measuring the reaction intermediates in the solution mixture.
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assay for the simultaneous determination of guanidinoacetic acid creatinine and creatine in plasma and urine by capillary electrophoresis uv detection
Journal of Separation Science, 2006Co-Authors: Angelo Zinellu, Salvatore Sotgia, Luca Deiana, Elisabetta Zinellu, Roberto Chessa, Ciriaco CarruAbstract:Guanidinoacetic acid (GAA) measurement has recently become of great interest for the diagnosis of creatine (Cn) metabolism disorders, and research calls for rapid and inexpensive methods for its detection in plasma and urine in order to assess a large number of patients. We propose a new assay for the measurement of GAA by a simple CZE UV-detection without previous sample derivatization. Plasma samples were filtered by Microcon-10 microconcentrators and directly injected into the capillary, while for urine specimens a simple water dilution before injection was needed. A baseline separation was obtained in less than 8 min using a 60.2 cm x 75 microm uncoated silica capillary, 75 mmol/L Tris-Phosphate buffer pH 2.25 at 15 degrees C. The performance of the developed method was assessed by measuring plasma creatinine and Cn in 32 normal subjects and comparing the data obtained by the new method with those found with the previous CE assay. Our new method seems to be an inexpensive, fast and specific tool to assess a large number of patients both in clinical and in research laboratories.
Juan Fernando Padin - One of the best experts on this subject based on the ideXlab platform.
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altered mitochondrial function calcium signaling and catecholamine release in chromaffin cells of diabetic and shr rats
European Journal of Pharmacology, 2017Co-Authors: Diego Castro Musial, Aron Jurkiewicz, Antonio G Garcia, Guilherme Henrique Souza Bomfim, Iago Mendezlopez, Juan Fernando Padin, Neide H Jurkiewicz, Regiane Mirandaferreira, Juan Alberto ArranztagarroAbstract:Comorbidity of diabetes and hypertension is frequent. Here, we have performed a comparative study in three animal models namely, normotensive Wistar Kyoto (WKY) rats, streptozotocin-induced diabetic rats (STZ), and spontaneously hypertensive rats (SHR). With respect WKY rats, we have found the following alterations in adrenal chromaffin cells from STZ and SHR rats: (1) diminished Ca2+ currents; (2) augmented [Ca2+]c elevations and catecholamine release in cells stimulated with angiotensin II or high K+; (3) unchanged expression of angiotensin II receptors AT1 and AT2; (4) higher density of secretory vesicles at subplasmalemmal sites; (5) mitochondria with lower cristae density that were partially depolarized; and (6) lower whole cell ATP content. These alterations may have their origin in (i) an augmented capacity of the endoplasmic reticulum [Ca2+] store likely due to (ii) impaired mitochondrial Ca2+ uptake; (iii) augmented high-[Ca2+]c microdomains at subplasmalemmal sites secondary to augmented calcium-induce calcium release and to inositol Tris-Phosphate receptor mediated enhanced Ca2+ mobilization from the endoplasmic reticulum; and (iv) augmented vesicle pool. These alterations seem to be common to the two models of human hypertension here explored, STZ diabetic rats and SHR hypertensive rats.
Kevin J Foskett - One of the best experts on this subject based on the ideXlab platform.
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inositol 1 4 5 Tris Phosphate activation of inositol Tris Phosphate receptor ca2 channel by ligand tuning of ca2 inhibition
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Sean M J Mcbride, Kevin J FoskettAbstract:Inositol 1,4,5-Tris-Phosphate (IP3) binding to its receptors (IP3R) in the endoplasmic reticulum (ER) activates Ca2+ release from the ER lumen to the cytoplasm, generating complex cytoplasmic Ca2+ concentration signals including temporal oscillations and propagating waves. IP3-mediated Ca2+ release is also controlled by cytoplasmic Ca2+ concentration with both positive and negative feedback. Single-channel properties of the IP3R in its native ER membrane were investigated by patch clamp electrophysiology of isolated Xenopus oocyte nuclei to determine the dependencies of IP3R on cytoplasmic Ca2+ and IP3 concentrations under rigorously defined conditions. Instead of the expected narrow bell-shaped cytoplasmic free Ca2+ concentration ([Ca2+]i) response centered at ≈300 nM–1 μM, the open probability remained elevated (≈0.8) in the presence of saturating levels (10 μM) of IP3, even as [Ca2+]i was raised to high concentrations, displaying two distinct types of functional Ca2+ binding sites: activating sites with half-maximal activating [Ca2+]i (Kact) of 210 nM and Hill coefficient (Hact) ≈2; and inhibitory sites with half-maximal inhibitory [Ca2+]i (Kinh) of 54 μM and Hill coefficient (Hinh) ≈4. Lowering IP3 concentration was without effect on Ca2+ activation parameters or Hinh, but decreased Kinh with a functional half-maximal activating IP3 concentration (KIP3) of 50 nM and Hill coefficient (HIP3) of 4 for IP3. These results demonstrate that Ca2+ is a true receptor agonist, whereas the sole function of IP3 is to relieve Ca2+ inhibition of IP3R. Allosteric tuning of Ca2+ inhibition by IP3 enables the individual IP3R Ca2+ channel to respond in a graded fashion, which has implications for localized and global cytoplasmic Ca2+ concentration signaling and quantal Ca2+ release.
