Mechanism of arginine-stimulated Ca2+ influx into pancreatic B cell.
The mechanism by which arginine stimulates Ca2+ inflow into the pancreatic B cell was investigated. Arginine (10 mM) increased 86Rb outflow from perifused rat pancreatic islets, suggesting that arginine-stimulated Ca2+ influx into the B cell does not result from a decrease in K+ conductance. Arginine stimulated Ca2+ uptake in isolated islets over short incubation periods and increased 45Ca outflow from perifused islets in a Ca2+-dependent manner. The calcium channel blocker verapamil inhibited both arginine-stimulated 45Ca uptake and 45Ca outflow. However, the sensitivity toward verapamil of arginine-stimulated islets was lower than that of islets stimulated by 20 mM K+, which gates voltage-sensitive Ca2+ channels. It was similar to that of islets stimulated by 8.3 mM glucose, which is thought to mainly gate voltage-insensitive Ca2+ channels. It is suggested that arginine stimulates Ca2+ inflow into the B cell by gating voltage-insensitive Ca2+ channels. The arginine-induced stimulation of Ca2+ inflow could participate in the depolarizing action of the amino acid on the B cell membrane.
D000818:Animals; D001120:Arginine / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D012413:Rubidium / Q000378:metabolism; D014700:Verapamil / Q000494:pharmacology
D007473:Ion Channels; D001120:Arginine; D014700:Verapamil; D012413:Rubidium; D011188:Potassium; D002118:Calcium