STUDIES ON THE RATE OF RUNOUT OF N-METHYLNICOTINAMIDE FROM DOG RENAL SLICES

¹ Department of Pharmacology, State University of New York, Update Medical Center, Syracuse, New York

The runout of N-methylnicotinamide from dog renal slices has been studied and compared with that of p-aminohippurate. N-Methylnicotinamide runout is not influenced by metabolic inhibitors such as dinitrophenol, iodoacetate and cyanide in concentrations which completely inhibit uptake of N-methylnicotinamide by dog renal slices. The competitive inhibitors, cyanine dye 863 and mepiperphenidol (Darstine) produce a partial reduction of the rate of runout of N-methylnicotinamide in concentrations which inibit uptake completely. Tolazoline (Priscoline) has minimal while tetraethylammonium has no effect on the rate of runout of N-methylnicotin-amide in concentrations which inhibit its uptake completely. These results have been compared and contrasted with those obtained previously with p-aminohippurate and it is concluded that in the N-methylnicotinamide system counter transport cannot be demonstrated. The runout of NMN probably has a passive component uninfluenced by inhibitors and a second component which is carrier mediated.