Effect of somatostatin on amylase secretion fromin vivo andin vitro rat pancreas

Abstract

In the present study the effect of somatostatin on amylase secretion was determined usingin vivo cannulation and isolated acini from rat pancreas.In vivo somatostatin-14 inhibited amylase secretion in basal state and that stimulated with CCK8 and acetylcholine. Somatostatin-14 and somatostatin-28 failed to inhibit amylase secretion from isolated acini in basal state and that stimulated with CCK8 and bethanechol. Somatostatin-14 did not increase⁴⁵Ca uptake or efflux of label from acini preloaded with⁴⁵Ca. Cellular cyclic AMP levels were not significantly increased. Somatostatin-14 did not alter the synthesis of proteinsin vitro, as judged by incorporation of a mixture of fifteen¹⁴C-labeled amino acids. Somatostatin-14 stimulated phosphoprotein phosphatase in higher doses, whereas no effect was observed at lower doses. Inhibition of secretionin vivo and lack of stimulation of amylase secretion in isolated acini suggest that the somatostatin effectin vivo is mediated by an indirect effect similar to other peptides, for example, opiates and neurotensin. Stimulation of phosphoprotein phosphatase suggests that somatostatin may bind to the acinar cells and affect functions other than secretion and synthesis of enzymes.