EFFECTS OF ENANTIOMERS OF INDACRINONE (MK-196) ON CATION-TRANSPORT BY THE LOOP OF HENLE AND DISTAL TUBULE STUDIED BY MICROPERFUSION INVIVO

  • 1 January 1984
    • journal article
    • research article
    • Vol. 230  (1) , 62-68
Abstract
The effects of the 2 enantiomeric forms of the diuretic agent, indacrinone (MK-196) were studied, upon transport of Na and K by the loop of Henle and distal tubule, using the technique of continuous microperfusion, in vivo, of individual tubular segments in the rat kidney. In the loop of Henle, both the (+)- and (-)-enantiomers, when included in the tubular perfusion fluid at a concentration of 5 .times. 10-4 M, inhibited the reabsorption of Na and K, but the (-)-enantiomer was significantly more effective in this regard than the (+)-enantiomer. Although loop Na reabsorption was incompletely blocked by either form of the drug, K reabsorption by the loop was on average abolished by (-)-MK-196 and was actually converted in some experiments to an appreciable net secretory flux. In the distal tubule, both enantiomers inhibited net Na reabsorption, but neither affected the control level of K secretion. The natriuretic effect of this agent is evidently due to actions on Na transporting sites in the loop of Henle and distal tubule. Because K transport was affected only in the loop, they suggest that the nature of the cellular cation transport mechanism influenced by the drug may be different at the 2 nephron sites studied.