CALCIUM EFFLUX AND SECRETION OF a-AMYLASE FROM RAT PANCREAS

1 The efflux of 45Ca from rat pancreas was investigated in relation to the secretion of c-amylase. 2 The 45Ca space in the pancreas was increased 1.6 times when pancreatic tissue was incubated in media in which the extracellular calcium concentration was reduced from 1.0 to 0.05 mM. 3 Carbachol increased the rate of 45Ca efflux from the tissue and this effect was associated with an increase in the release of a-amylase. Dibutyryl cyclic adenosine monophosphate (AMP) also evoked a secretory response, but did not alter the rate of 45Ca efflux. In combination with carbachol, the dibutyryl analogue of cyclic AMP reduced the carbachol-stimulated increase in 45Ca efflux while enhancing the release of secretory protein. 4 The stimulatory effect of carbachol on 45Ca efflux was observed when pancreatic tissues were incubated in media containing a high concentration of ethyleneglycolbis (,B-aminoethyl)N,NA-tetraacetic acid (EGTA).