Transport of guanidine in rabbit intestinal brush-border membrane vesicles.

摘要: The characteristics of guanidine uptake were studied in brush-border membrane vesicles isolated from the rabbit proximal intestine. Guanidine was manyfold greater presence an outward-directed H+ gradient (intracellular pH = 5.5; extracellular 7.2) than absence a and 7.2). time course exhibited overshoot phenomenon gradient, indicating occurrence uphill transport. This gradient-stimulated not due to inside-negative H+-diffusion potential because carbonyl cyanide 4-trifluoromethoxyphenylhydrazone, protonophore, failed have any effect on uptake. Moreover, transient transport observed even voltage-clamped vesicles. However, under conditions that effectively dissipated there no active guanidine. gradient-dependent mechanism for is distinct Na+-H+ exchanger, amiloride did inhibit at concentration as high 100 microM. These data provide evidence guanidine-H+ antiport system intestinal membrane. carrier these membranes further substantiated by trans-stimulation radiolabeled unlabeled inhibition imipramine equilibrium exchange conditions.(ABSTRACT TRUNCATED AT 250 WORDS)