Effects of lysine on bicarbonate and fluid absorption in the rat proximal tubule
Chan, Y.L.; Kurtzman, N.A.
American Journal of Physiology 242(6): F604-F609
1982
ISSN/ISBN: 0002-9513 PMID: 6807097 Document Number: 185517
The effects of lysine on HCO3- and fluid reabsorption in the rat proximal tubule were studied by luminal and capillary perfusion in situ. The proximal tubule and peritubular capillaries were perfused with HCO3- Ringer solution containing [14C]inulin. The rate of HCO3- reabsorption (JHCO3) was estimated to be 124 .+-. 9.5 peq/min per mm using a pH membrane glass electrode. The rate of net fluid reabsorption (Jv) was 2.6 .+-. 0.21 nl/min per mm. When 10 mM L-lysine was added to the luminal perfusate, a 35% reduction in JHCO3 and no change in Jv were observed. Increase of L-lysine concentration in the luminal perfusate to 20 mM did not reduce JHCO3 further nor did it influence Jv. When 10 mM L-lysine was added to the capillary perfusate, a 13% reduction in HHCO3 was observed (NS). Increase of lysine concentration in the capillary perfusate to 20 mM significantly reduced JHCO3 by 26% (P < 0.01). There was no significant change in Jv under both conditions. The effect of L-lysine in the lumen was related to its reabsorption kinetics. D-Lysine, which was not reabsorbed significantly, did not affect HCO3- reabsorption in the proximal tubule. The inhibitory effect of L-lysine may be related to the entry of lysine into the cell from the lumen.