Effect of ‘Furosemid’ on Chloride and Water Excretion in Single Nephrons of the Kidney of the Rat

Abstract

IT has been shown by Muschaweck and Hajdú¹ that in the dog, at doses of 10 mg/kg body-wt. and more, ‘Furosemid’ (4-chloro-N(2-furylmethyl)-5-sulphamoyl-anthranylic acid) markedly increases the excretion of water, sodium and chloride. These authors also showed that the increase in chloride excretion was proportionally greater than that of sodium and water. On the other hand, Karger and Nagel² found a reduced permeability to anions, especially chloride, in the frog skin after addition of ‘Furosemid’ at concentrations of 25–500 mg/1. to the bathing solution, as evidenced by increased transmembrane potential differences without change in the short circuit current. Deetjen³ obtained proximal and distal tubular fluid samples in rats with an intravenous infusion of 2 mg/kg/min and observed significantly decreased proximal fluid/plasma (F/P) inulin ratios, as well as ratios below 2 in the distal tubule, concluding that ‘Furosemid’ depresses water and salt re-absorption in the proximal tubule and ascending limb of Henle's loop. Clearance studies by Suki, Rector and Seldin⁴ also indicated that ‘Furosemid’ might have an effect on the activity of the re-absorptive mechanisms of the proximal tubule and the ascending limb of Henle's loop.