Effects of sulfhydryl reagent, p-chloromercuribenzoate, on p-aminohippurate transport by isolated, perfused snake renal tubules

Effects of mercaptide-forming sulfhydryl reagent, p-chloromercuribenzoate (PCMB), on transport of p-aminohippurate (PAH) by isolated, perfused snake (Thamnophis species) renal tubules were studied. PCMB (10^-7 mol/l) in bathing medium irreversibly inhibited net transepithelial transport of PAH (J(PAH)) without affecting net fluid absorption (J(V)). PCMB (10^-8 mol/l) in perfusate irreversibly inhibited J(PAH) without affecting J(v) and markedly reduced the apparent permeability of the luminal membrane to PAH. These data suggest that sulfhydryl groups may be involved in the PAH transport steps at both the peritubular and luminal membranes.