Glucagon secretion and intracellular calcium distribution in pancreatic A cells

Quantitative changes in the distribution of intracellular calcium in A cells from perfused rat pancreas in relation to the secretory state of A cells were studied with the pyroantimonate technique for calcium precipitation. A cells stimulated with a 3.3 mM glucose concentration in the perfusate presented numerous calcium precipitates attached to cell membranes, nucleus, cytoplasm and secretion granules. Independently of the length of treatment, inhibition of glucagon release with 16.6 mM glucose decreased the calcium precipitates in every cell organelle studied. These results suggest that intracellular calcium rearrangement might be important in coupling stimulus to secretion in A cells, as it has been demonstrated for pancreatic B cells.