Somatostatin inhibits duodenal calcium transport mediated by 1,25-dihydroxyvitamin D3 in perfused duodena from normal chicks

We have reported that physiological dose (30pM-650pM) of 1,25-dihydroxyvitamin D3[1,25(OH)2D3] increased the unidirectional movement of45Ca2+ from the lumen to the venous effluent within a few minutes in perfused duodena from normal chicks, and hypercalcemia inhibited this rapid stimulatory effect on calcium transport mediated by 1,25(OH)2 D3. The purpose of the present study was to determine the effect of somatostatin on calcium transport in chicks. The basal Ca2+ transport, in the absence of 1,25(OH)2 D3, did not change when 10−8M to 10−6M of somatostatin was added to the perfusate. The effect of 1,25(OH)2D3 on calcium transport, however, was completely abolished on addtion of 10−6M somatostatin in the perfusate, and partially blocked on addition of 10−7M somatostatin and 10−8M somatostatin had no effect on 1,25(OH)2 D3 mediated calcium transport. These results suggest that somatostatin may decrease intestinal calcium transport mediated by the rapid direct action of 1,25(OH)2 D3.