Renal acid-base metabolism after ischemia.
The response of the kidney to ischemia-induced cellular acidosis was followed over the immediate one hr post-ischemia reflow period. Clearance and extraction experiments as well as measurement of cortical intracellular pH (pHi) were performed on Inactin-anesthetized Sprague-Dawley rats. Arteriovenous concentration differences and para-aminohippurate extraction were obtained by cannulating the left renal vein. Base production was monitored as bicarbonate released into the renal vein and urine; net base production was related to the renal handling of glutamine and ammonia as well as to renal oxygen consumption and pHi. After a 15 min control period, the left renal artery was snared for one-half hr followed by release and four consecutive 15 min reflow periods. During the control period, cortical cell pHi measured by [14C]-5,5-Dimethyl-2,4-Oxazolidinedione distribution was 7.07 +/- 0.08, and Q-O2 was 14.1 +/- 2.2 micromoles/min; neither net glutamine utilization nor net bicarbonate generation occurred. After 30 min of ischemia, renal tissue pH fell to 6.6 +/- 0.15. However, within 45 min of reflow, cortical cell pH returned and exceeded the control value, 7.33 +/- 0.06 vs. 7.15 +/- 0.08. This increase in pHi was associated with a significant rise in cellular metabolic rate, Q-O2 increased to 20.3 +/- 6.4 micromoles/min. Corresponding with cellular alkalosis was a net production of bicarbonate and a net ammonia uptake and glutamine release; urinary acidification was abolished. These results are consistent with a nonexcretory renal metabolic base generating mechanism governing cellular acid base homeostasis following ischemia.
D000141:Acidosis, Renal Tubular / Q000209:etiology* / Q000378:metabolism; D000471:Alkalosis / Q000209:etiology / Q000378:metabolism; D000641:Ammonia / Q000378:metabolism; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D005919:Glomerular Filtration Rate; D005973:Glutamine / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007511:Ischemia / Q000378:metabolism*; D007668:Kidney / Q000098:blood supply* / Q000378:metabolism; D007672:Kidney Cortex / Q000378:metabolism; D008297:Male; D010101:Oxygen Consumption; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D001639:Bicarbonates; D005973:Glutamine; D000641:Ammonia