Gossypol, ouabain and vanadate on the isolated perfused rat kidney and Na, K-ATPase

Gossypol, ouabain, and vanadate were tested on the isolated perfused rat kidney preparation (IPRK). Gossypol decreased Na reabsorption, urinary K concentration, and glomerular filtration rate (GFR). Ouabain decreased Na reabsorption, K concentration, and GFR, but increased urine flow, renal vascular resistance and osmolar clearance. Ouabain was also tested in combination with vanadate in the IPRK. The effect of gossypol was tested on rat kidney microsomes: half-maximal inhibition of Na, K-ATPase occurred at 2.4μM gossypol, and Mg-ATPase was half-maximally inhibited at 36 μM gossypol. On the same microsomes ouabain inhibited Na,K-ATPase, but not Mg-ATPase.When gossypol was administered to intact rats,it caused a diuresis and a decrease in plasma K levels. It is concluded that gossypol exerts effects that are different from those of ouabain and eanadate.