PT  - JOURNAL ARTICLE
AU  - Antoine, M H
AU  - Hermann, M
AU  - Herchuelz, A
AU  - Lebrun, P
TI  - Ionic and secretory response of pancreatic islet cells to minoxidil sulfate.
DP  - 1991 Jul 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 286--291
VI  - 258
IP  - 1
4099  - http://jpet.aspetjournals.org/content/258/1/286.short
4100  - http://jpet.aspetjournals.org/content/258/1/286.full
SO  - J Pharmacol Exp Ther1991 Jul 01; 258
AB  - Minoxidil sulfate is an antihypertensive agent belonging to the new class of vasodilators, the "K+ channel openers." The present study was undertaken to characterize the effects of minoxidil sulfate on ionic and secretory events in rat pancreatic islets. The drug unexpectedly provoked a concentration-dependent decrease in 86Rb outflow. This inhibitory effect was reduced in a concentration-dependent manner by glucose and tolbutamide. Minoxidil sulfate did not affect 45Ca outflow from islets perfused in the presence of extracellular Ca++ and absence or presence of glucose. However, in islets exposed to a medium deprived of extracellular Ca++, the drug provoked a rise in 45Ca outflow. Whether in the absence or presence of extracellular Ca++, minoxidil sulfate increased the cytosolic free Ca++ concentration of islet cells. Lastly, minoxidil sulfate increased the release of insulin from glucose-stimulated pancreatic islets. These results suggest that minoxidil sulfate reduces the activity of the ATP-sensitive K+ channels and promotes an intracellular translocation of Ca++. The latter change might account for the effect of the drug on the insulin-releasing process. However, the secretory response to minoxidil sulfate could also be mediated, at least in part, by a modest Ca++ entry.