| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Departamento de Fisiología, Facultad de Medicina, Universidad de Alicante, Spain.
1. The characteristics of the electrical activity of beta-cells from islets of Langerhans recorded in vivo are described. For blood glucose concentrations from 4 to 11 mM, the electrical activity of pancreatic beta-cells is oscillatory, with alternating depolarized and hyperpolarized phases. During the depolarized phases, action potentials are triggered. 2. The main effect of increasing glucose concentration consists of an increase in the duration of the depolarized phase. The relationship between blood glucose concentration and the percentage of time in the depolarized phase can be described by a sigmoidal function with half-activation at 6.8 mM glucose. The equivalent value obtained in parallel experiments in vitro is 13.3 mM, a significant rightward shift in the activation curve that suggests a role for other neural or humoral factors in determining the islet sensitivity to glucose. 3. The injection of glucose into the bloodstream produces a transitory phase of continuous electrical activity that is recorded within seconds after the change and that leads to a decrease of the glycaemia to the prestimulatory value. 4. The results demonstrate that under physiological conditions the electrical response of beta-cells to glucose consists of membrane potential oscillations, validating previous data obtained with isolated preparations. Furthermore, the electrical response occurs at lower levels of glycaemia than those predicted from recordings in isolated preparations and is maximal within the physiological range of blood glucose.
This article has been cited by other articles:
|
|
 |
|
  L. Eliasson, F. Abdulkader, M. Braun, J. Galvanovskis, M. B. Hoppa, and P. Rorsman Novel aspects of the molecular mechanisms controlling insulin secretion J. Physiol., July 15, 2008; 586(14): 3313 - 3324. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. Tuduri, E. Filiputti, E. M. Carneiro, and I. Quesada Inhibition of Ca2+ signaling and glucagon secretion in mouse pancreatic {alpha}-cells by extracellular ATP and purinergic receptors Am J Physiol Endocrinol Metab, May 1, 2008; 294(5): E952 - E960. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. S. Nunemaker, R. Bertram, A. Sherman, K. Tsaneva-Atanasova, C. R. Daniel, and L. S. Satin Glucose Modulates [Ca2+]i Oscillations in Pancreatic Islets via Ionic and Glycolytic Mechanisms Biophys. J., September 15, 2006; 91(6): 2082 - 2096. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 I. Quesada, M. G. Todorova, P. Alonso-Magdalena, M. Beltra, E. M. Carneiro, F. Martin, A. Nadal, and B. Soria Glucose Induces Opposite Intracellular Ca2+ Concentration Oscillatory Patterns in Identified {alpha}- and {beta}-Cells Within Intact Human Islets of Langerhans Diabetes, September 1, 2006; 55(9): 2463 - 2469. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
I. Quesada, M. G. Todorova, and B. Soria Different Metabolic Responses in {alpha}-, {beta}-, and {delta}-Cells of the Islet of Langerhans Monitored by Redox Confocal Microscopy Biophys. J., April 1, 2006; 90(7): 2641 - 2650. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. S. Nunemaker, M. Zhang, D. H. Wasserman, O. P. McGuinness, A. C. Powers, R. Bertram, A. Sherman, and L. S. Satin Individual Mice Can Be Distinguished by the Period of Their Islet Calcium Oscillations: Is There an Intrinsic Islet Period That Is Imprinted In Vivo? Diabetes, December 1, 2005; 54(12): 3517 - 3522. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Jo, H. Kang, M. Y. Choi, and D.-S. Koh How Noise and Coupling Induce Bursting Action Potentials in Pancreatic {beta}-Cells Biophys. J., September 1, 2005; 89(3): 1534 - 1542. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Bertram, L. Satin, M. Zhang, P. Smolen, and A. Sherman Calcium and Glycolysis Mediate Multiple Bursting Modes in Pancreatic Islets Biophys. J., November 1, 2004; 87(5): 3074 - 3087. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 F. Ashcroft and P. Rorsman Type 2 diabetes mellitus: not quite exciting enough? Hum. Mol. Genet., April 1, 2004; 13(suppl_1): R21 - R31. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Bergsten, J. Westerlund, P. Liss, and P.-O. Carlsson Primary In Vivo Oscillations of Metabolism in the Pancreas Diabetes, March 1, 2002; 51(3): 699 - 703. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Bergsten Role of Oscillations in Membrane Potential, Cytoplasmic Ca2+, and Metabolism for Plasma Insulin Oscillations Diabetes, February 1, 2002; 51(90001): S171 - 176. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. H. Song, L. Kjems, R. Ritzel, S. M. McIntyre, M. L. Johnson, J. D. Veldhuis, and P. C. Butler Pulsatile Insulin Secretion by Human Pancreatic Islets J. Clin. Endocrinol. Metab., January 1, 2002; 87(1): 213 - 221. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Gilon and J.-C. Henquin Mechanisms and Physiological Significance of the Cholinergic Control of Pancreatic {beta}-Cell Function Endocr. Rev., October 1, 2001; 22(5): 565 - 604. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. Magnus and J. Keizer Model of beta -cell mitochondrial calcium handling and electrical activity. I. Cytoplasmic variables Am J Physiol Cell Physiol, April 1, 1998; 274(4): C1158 - C1173. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. D. Weaver, T. L. Yao, A. C. Powers, and T. A. Verdoorn Differential Expression of Glutamate Receptor Subtypes in Rat Pancreatic Islets J. Biol. Chem., May 31, 1996; 271(22): 12977 - 12984. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
