INTERACTION OF SECRETIN WITH BASOLATERAL MEMBRANE FRACTION FROM RAT GASTRIC MUCOSA : MEMBRANE PREPARATION AND SECRETIN BINDING

Abstract

Studies on secretin receptors of the stomach need an appropriate methodology. Plasma membrane fraction enriched in basolateral membranes was obtained from rat gastric mucosa using differential centrifugation and Percoll density gradient centrifugation. (Na⁺+K⁺)-ATPase, a marker enzyme for basolateral membranes, was enriched 10.5-fold compared with that found in the homogenate. The binding of ¹²⁵I-[Tyr¹] secretin to the basolateral membrane fraction was rapid, reversible and saturable with an equilibrium K_d of 6.4 nM and the binding capacity of 0.6 pmol/mg of protein.