Abstract

Effects of the peptidoleukotriene receptor antagonist, SK&F 104353, were examined in vitro using stripped rat ileal mucosa in Ussing chambers. Changes in short-circuit current (Isc), transepithelial conductance (G1) and unidirectional and net Na+ and Cl fluxes measured in the absence or presence of SK&F 104353 (1 microM) revealed that serosal addition produced a decrease in net Na+ absorption and serosal-to-mucosal Cl- flux. Serosal addition of leukotriene (LT)D4 (10 muM) or LTE4 (10 microM) elicited transient increases in Isc and sustained decreases in G1 which were antagonized by serosal addition of SK&F 104353 in a concentration-dependent manner. Mucosal addition of SK&F 104353 (1 microM) also reduced the increase in Isc elicited by LTD4 (10 microM). LTD4 (10 microM) decreased unidirectional and net Na+ and Cl- fluxes along with G1 in the steady state. All of these changes were abolished by pretreatment with SK&F 104353 (1 microM). The intestinal secretagogues prostaglandin F2 alpha, histamine, serotonin, substance P and the thromboxane mimic, U46619, produced changes in Isc qualitatively similar to those of LTD4. However, the transient increase in Isc produced by these secretagogues was not antagonized by SK&F 104353 (1 microM). Additionally, lysbradykinin- and prostaglandin E1-induced increases in Isc were not antagonized by SK&F 104353 (1 microM). Stimulation with histamine (10 microM) or pretreatment with LTB4 (5 microM) did not alter the increase in Isc or decrease in Gt produced by the subsequent addition of LTD4 (10 microM). Pretreatment of the tissues with mepyramine (10 microM) also did not reduce the increase in Isc elicited by LTD4 (10 microM), although it inhibited completely the increase in Isc produced by histamine (10 microM).(ABSTRACT TRUNCATED AT 250 WORDS)