Effects of Zn2+ on glucose-induced electrical activity and insulin release from mouse pancreatic islets

R Ferrer, B Soria, CM Dawson… - American Journal of …, 1984 - journals.physiology.org
R Ferrer, B Soria, CM Dawson, I Atwater, E Rojas
American Journal of Physiology-Cell Physiology, 1984journals.physiology.org
METHODS Electrical measurements on single microdissected mouse islets of Lungerhans.
The electrophysiological methods used in this work have been previously described (6) The
modified Krebs solution used during the experiments had the following composition (in mM):
120 NaCl, 25 NaHC03, 5 KCl, 2.5 CaC12, and 1.1 MgCl, and was equilibrated with 95% 02-
5% CO2 at 37OC. The volume of the chamber for the microelectrode experiments was 0.04
cm3, and the rate of perfusion was controlled at 1.5 cm3/min. When changing the solution …
METHODS
Electrical measurements on single microdissected mouse islets of Lungerhans. The electrophysiological methods used in this work have been previously described (6)
The modified Krebs solution used during the experiments had the following composition (in mM): 120 NaCl, 25 NaHC03, 5 KCl, 2.5 CaC12, and 1.1 MgCl, and was equilibrated with 95% 02-5% CO2 at 37OC. The volume of the chamber for the microelectrode experiments was 0.04 cm3, and the rate of perfusion was controlled at 1.5 cm3/min. When changing the solution, the test solution reached the chamber 2 s after the switch at the stopcock. In each figure, we indicate the time of switching the solution at the stopcock. Solutions with added ZnClz or CoC12 were prepared 10 min prior to use from 1 M ZnC12 (or CoC12) stock solutions. Addition of up to 1 mM ZnCl2 or CoC12 to the Krebs-bicarbonate medium used did not alter the pH. Spike analysis was made from portions of the electrical recording played back with an expanded time base. The amplitude of each voltage deflection greater than 1 mV during the active phase of at least 10 bursts was measured using an Apple II graphics tablet. Multi-islet perifusion and insulin release. The medium used in these experiments was identical to the modified Krebs solution used in the electrophysiological experiments plus 5 mg/cm3 bovine serum albumin (BSA)(Armour Pharmaceuticals, Eastbourne, UK) and either 5.6 or 22.2 mM glucose. ZnCl2 or CoC12 were added to the Krebs 5 min before using the solution. In experiments where the extracellular K+ was changed, KC1 was substituted for NaCl and no glucose was present during the collection period.
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