Nicotinamide and the regulation of renal phosphate transport.

The specific inhibitory action of nicotinamide on renal Pi transport does not require de novo protein synthesis and can be detected within 1 hr, at least in low Pi diet rats. These properties characterize nicotinamide as a rapidly acting regulator of the Pi transport system in the renal BBM (Kempson and Dousa, 1986). The studies with LLC-PK 1 cells strongly suggest that the action of nicotinamide in rats is due to a direct effect on the cells of the proximal tubule. Further studies on the mechanism of action of nicotinamide may lead to an understanding of the intracellular mechanisms that mediate the action of rapidly acting physiological regulators of BBM transport of Pi.