Somatostatin and intestinal calcium transport in the rat

In intact rats we studied the influence of low doses of intravenously (i.v.) administered somatostatin (SRIF) on the net absorption and the bidirectional fluxes (lumen-to-plasma, LP; plasma-to-lumen, PL) of calcium in the duodenum, jejunum, ileum and caecum. In the duodenum SRIF inhibited the LP-flux and the net absorption of Ca significantly at infusion rates of 0.75 and 1.0 μg SRIF·kg −1·h −1. The PL-flux was not altered by any of the SRIF doses administered. In the other gut segments studied (jejunum, ileum, caecum) neither the net absorption nor the bidirectional Ca fluxes were changed by i.v. SRIF. It is concluded that (1) SRIF in the plasma levels achieved in this study has an influence on the duodenal calcium absorption (CaA) of the rat; (2) questions regarding the mechanisms of this action as well as the physiological significance of our findings are as yet unresolved.