RELEASE OF SOMATOSTATIN IMMUNOREACTIVITY FROM HUMAN ANTRAL D-CELLS IN CULTURE

A primary culture of human antral somatostatin cells has been developed and used in release studies. The phorbol ester, phorbol 12 myristrate 13-acetate, caused a concentration-dependent increase in immunoreactive somatostatin secretion with a 1-μmol/L concentration resulting in a 40-fold stimulation (basal 0.28% ± 0.7% total cell content vs. 13.8% ± 2.2% TCC, P < 0.005). The calcium ionophore, A23187, resulted in a significant stimulation only at 1 μmol/L (basal 0.28% ± 0.7% TCC vs. 2.2% ± 0.5% total cell content, P < 0.05). However, addition of the ionophore at 1 μmol/L with the phorbol ester resulted in a potentiation of the response at all concentrations tested. Removal of extracellular calcium by chelation with EGTA reduced the response to that seen with the phorbol ester alone. Forskolin at 0.1 mmol/L resulted in a five-fold increase (basal 0.6% ± 0.2% total cell content vs. 2.8% ± 0.9% total cell content, P < 0.02) and was 1000-fold less potent than the phorbol ester. The peptides bombesin and gastrin at concentrations up to 1 μmol/L had no effect on basal secretion. Cholecystokinin-8 significantly stimulated somatostatin secretion with a maximal effect at 0.1 μmol/L resulting in an eightfold increase (basal 0.2% ± 0.04% total cell content vs. 1.5% ± 0.4% total cell content, P < 0.02). These results indicate that human antral D cells are more responsive to agents acting through the c-kinase pathway (phorbol 12 myristrate 13-acetate, A23187, and cholecystokinin) than adenylate cyclase (forskolin). © 1990.