Distribution and metabolism of [Asu1,7]-eel calcitonin in isolated perfused rat pancreas.

Abstract

The distribution and metabolism of elcatonin ([Asu1, 7]-eel calcitonin) were studied in isolated perfused rat pancreas. During the perfusion of 125I-elcatonin, the radioactivity in the effluent rapidly attained equilibrium with the perfusate, although a considerable quantity of degradation products was observed in the effluent. The distribution space of 125I-elcatonin was considered to be limited to the extracellular space. When unlabeled elcatonin was perfused, immunoreactive elcatonin concentration in the effluent also reached a rapid equilibrium at a lower level than that in the perfusate. These results suggest that the pancreas can degrade the entering elcatonin fairly well. The inclusion of insulin or aprotinin in the perfusate significantly suppressed elcatonin metabolism by the pancreas. Although a study of elcatonin inactivation by several proteases did not clarify the inhibitory mechanism of insulin, serine proteases were considered to be involved in the inactivation of elcatonin by the pancreas.