INTERLEUKIN-1 INHIBITS SODIUM AND WATER TRANSPORT IN RABBIT CORTICAL COLLECTING DUCT

Interleukin-1 (IL-1) induces natriuresis and diuresis. In the present study, the effect of basolateral IL-1 on sodium and water transport wa s examined in the cortical collecting duct (CCD) perfused in vitro. IL -1, 10 pg/ml and 10 ng/ml, inhibited lumen-to-bath sodium flux (J(Na), peq.min(-1).mm tubule(-1)), depolarizing transepithelial voltage (V-t ) in a time- and dose-dependent manner. The inhibitory effect of 10 ng /ml but not 10 pg/ml IL-1 on V-t and J(Na) was mitigated by 5 mu M ind omethacin (IND) in bath. Also, 10 ng/ml IL-1, which did not affect the basal hydraulic conductivity (L(p), x 10(-7) cm.atm(-1).s(-1)) by its elf, inhibited the hydrosmotic effect of 20 pM basolateral arginine va sopressin, and 5 mu M IND abolished this inhibitory effect of 10 ng/ml IL-1. The present study demonstrated direct inhibitory effect of baso lateral IL-1 on sodium and water reabsorption in the rabbit CCD. The e ffect of IL-1 is suggested to be mediated, in part, by a cyclooxygenas e metabolite(s).