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Published on: January 19, 2012
Adrenaline inhibits depolarization-induced increases in capacitance the presence of elevated [Ca2+]i in insulin
S Lehr1, M Herbst, J Kampermann
1Physiologisches Institut, Albert-Ludwigs Universität Freiburg, Abteilung II, Freiburg/Br, Germany.
Abstract:
Cell capacitance (Cm), cell conductance (Gm), access conductance (Ga) and membrane voltage (Vm) were measured simultaneously in insulin secreting cells using the dual frequency method. Depolarization and stimulation of the cells with secretagogues increased Cm. EGTA abolished the increase in [Ca2+]i and prevented the rise of Cm. Adrenaline inhibited the augmentation of Cm without lowering [Ca2+]i. In pertussis toxin pretreated cells adrenaline had no effect. Thus, stimulation of insulin secretion is accompanied by an increase in Cm. Inhibition of exocytosis by adrenaline occurs even in the presence of elevated [Ca2+]i, i.e. at a more distal step of exocytosis.
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