AJP - Renal Physiology, Vol 250, Issue 5 785-F789, Copyright © 1986 by American Physiological Society
Dibucaine stimulation of p-aminohippurate accumulation in rat kidney cortical slices
M. Nakajima, S. Nakano and M. Gemba
We studied the effects of dibucaine on p-aminohippurate (PAH) transport
using rat kidney cortical slices. Addition of dibucaine in concentrations
from 0.01 to 0.1 mM stimulated PAH accumulation in a
concentration-dependent way; at higher concentrations, accumulation was
inhibited. Kinetic studies showed that dibucaine increased the apparent
maximal activity of PAH transport, whereas the apparent Km remained
essentially constant. The efflux of PAH from the slices was significantly
depressed by the drug. Dibucaine had no significant effect on the sodium
gradient, medium to intracellular fluid. The drug had biphasic effects on
hypotonic hemolysis; at lower concentrations (up to 0.2 mM) it protected
erythrocytes, and at much higher concentrations, it has a lytic effect. The
pattern of the membrane-stabilizing action of dibucaine was similar to that
of the stimulation of PAH accumulation. These results indicate that
dibucaine markedly stimulated accumulation of PAH. Stimulation by this drug
of PAH transport cannot be explained by the increase in the sodium
gradient; it may be due at least in part to membrane stabilization.
