摘要：Intrabiliary retrograde infusion of a fluorescent sulfhydryl reagent, N-[p-(2-benzimidazolyl) phenyl] maleimide (BIPM), to rats reduced the concentration in bile and the bile/liver concentration ratio of acetyl procainamide ethobromide (APAEB) to about a half of the control. The reagent is speculated to inhibit the active excretory process by binding to sulfhydryl groups of proteins involved in the active transport. By gel filtration on a Sephadex G-75 column of the bile sample collected after infusion of BIPM and Triton X-100 solution successively to rats, BIPM was found to be bound to proteins which did not occur in the normal bile. Polyacrylamide gel electrophoresis of the same sample showed that BIPM was bound to the major protein band in the gel. The binding of BIPM to the proteins occurred not only by infusion of BIPM in vivo but by addition of BIPM in vitro to the bile after treatment with Triton X-100. When APAEB or neutral red, an organic cation, was injected to rats before the treatment with Triton X-100, binding to the major band proteins of BIPM added to the bile sample was much depressed ; N-ethylmaleimide, PCMBS or iodoacetamide, a sulfhydryl reagent, also reduced the binding when infused retrogradely before the treatment with Triton X-100. The results of this experiment indicate that the major band proteins solubilized with Triton X-100 might be involved in the active transport of organic cations as BIPM was bound to the band and the binding was reduced by the pretreatment with organic cations and other sulfhydryl reagents.
