Kinetics of Na+ H+ exchange in vascular smooth muscle cells from WKY and SHR: effects of phorbol ester

A study of the kinetic properties of Na+ H+ exchange in vascular smooth muscle cells (VSMC) of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats pretreated with phorbol 12-myristate 13-acetate (PMA) reveals that PMA reduces Hill coefficient and enhances maximal activity in the SHR compared to WKY rats. PMA does not affect the kinetic variables of Na+ H+ antiport in the VSMC of SHR indicating a significant level of antiporter prestimulation.