Somatostatin inhibits the Na+/H+ exchange activity of rat hepatocytes in short term primary culture

Activation of the Na+/H+ exchanger is associated with cell growth and diffe rentiation. Our study has tested whether somatostatin-14 (SS-14), which is a potent inhibitor of Liver regeneration, has an inhibitory effect on the N a+/H+ exchange (NHE-1) of rat hepatocytes. We treated hepatocytes with SS-1 4 prior and after cell culture. NHE-1 activity of short term cultured hepat ocytes was estimated with the recovery rate of pH(i) after 9 min. acid-load ing in a sodium free buffer. Cultured with SS-14 (100 nM) inhibited signifi cantly the pH(i) recovery rate of hepatocytes, dpH(i)/dt and set point were significantly decreased in the presence of SS-14 in comparison to controls . The resting pH(i) of hepatocytes was not affected in the presence of SS-1 4. In contrast, addition of SS-14 after cell culture had no effect on the p H(i) recovery rate of hepatocytes. Therefore the inhibitory action of SS-14 on NHE-1 activity of rat hepatocytes appears to depend on the presence of the hormone in the early steps of the process of cell growth/adhesion. Inhi bition of SS-14 on NHE-1 activity seems to mediate, at least in part, its i nhibition on liver regeneration.