Measurements of cytoplasmic free Ca2+ concentration in human pancreatic islets and insulinoma cells

摘要

>In human pancreatic islets an increase in the glucose concentration from 3 to 20 mM raised the free cytoplasmic Ca2+ concentration ([Ca2+]_i), an effect being reversible upon withdrawal of the sugar. Depolarization with a high concentration of K+ or the sulphonylurea tolbutamide also raised [Ca2+]_i. Addition of extracellular ATP produced a transient rapid rise in [Ca2+]_i. Oscillations in [Ca2+]_i were observed in the presence of 10 mM glucose. Insulinoma cells responded to glucose and tolbutamide with increases in [Ca2+]_i, whereas the sulphonamide diazoxide caused a decrease in [Ca2+]_i. These findings confirm previous results obtained in rodent β-cells.