The effects of cobalt chloride, SKF-525A, and N-(3,5-dichlorophenyl)succinimide on in vivo hepatic mixed function oxidase activity as determined by single-sample plasma clearances

The antifungal antibiotic, clotrimazole, inhibits chloride secretion by human intestinal T84 cells via blockade of distinct basolateral K+ conductances. Demonstration of efficacy in intact rabbit colon and in an in vivo mouse model of cholera

The antifungal antibiotic clotrimazole (CLT) blocks directly and with high potency the Ca2+-activated K+ channels of human erythrocytes, erythroleukemia cells, and ferret vascular smooth muscle cells. We recently reported that CLT inhibits Cl- secretion in human intestinal T84 cells, likely by affecting K+ transport (Rufo, P.A., L. Jiang, S.J. Moe, C. Brugnara, S.L. Alper, and W.I. Lencer. 1996. J. Clin. Invest. 98:2066-2075). To determine if CLT had direct effects on K+ conductances in T84 cells, we selectively permeabilized apical membranes of confluent T84 cell monolayers using the ionophore amphotericin B. This technique permits direct measurement of basolateral K+ transport. We found that CLT and a stable des-imidazolyl derivative inhibited directly two pharmacologically distinct basolateral membrane K+conductances, but had no effect on apical membrane Cl- conductances. The effects of CLT on Cl- secretion were also examined in intact tissue. CLT inhibited forskolin-induced Cl- secretion in rabbit colonic mucosal sheets mounted in Ussing chambers by 91%. CLT also inhibited cholera toxin-induced intestinal Cl- secretion in intact mice by 94%. These data provide direct evidence that CLT blocks Cl- secretion in intestinal T84 cells by inhibition of basolateral K+ conductances, and show that CLT inhibits salt and water secretion from intact tissue in vitro and in vivo. The results further support the suggestion that CLT and its metabolites may show clinical efficacy in the treatment of secretory diarrheas of diverse etiologies.

Effect of dimethyl sulfoxide on N-(3,5-dichlorophenyl)succinimide (NDPS) and NDPS metabolite nephrotoxicity

Dimethyl sulfoxide (DMSO) is frequently used as a solvent to assist in dissolving compounds which are not readily soluble in other injection vehicles. The purpose of this study was to determine the suitability of DMSO as a vehicle for administering the nephrotoxicant, N-(3,5-dichlorophenyl)succinimide, (NDPS) and two nephrotoxicant NDPS metabolites, N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS) and N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (NDHSA). Male Fischer 344 rats (4/group) were administered a single intraperitoneal injection of NDPS (0.4 or 0.8 mmol/kg), NDHS (0.1 or 0.2 mmol/kg), or NDHSA (0.1 or 0.2 mmol/kg) dissolved in 25% DMSO in sesame oil or 100% sesame oil (2.5 ml/kg), while control rats received vehicle only. Renal function was then monitored at 24 and 48 h. Including DMSO in the vehicle markedly attenuated NDPS 0.4 mmol/kg-induced nephrotoxicity and reduced NDPS 0.8 mmol/kg-induced renal effects. Thus, the magnitude of the attenuating effect of DMSO depended in part on the nephrotoxicant dose of NDPS. In addition, NDHS nephrotoxicity was not altered by DMSO and only slight effects on NDHSA nephrotoxicity were observed. These results suggest that DMSO is capable of attenuating NDPS nephrotoxicity, and that the primary mechanism of this interaction might be due to an inhibition of the biotransformation of NDPS to NDHS.