Renal adaptation to chronic hypocapnia: dietary constraints in achieving H+ retention.
Previous studies suggested that renal H+ retention during adaptation to hypocapnia might be critically dependent upon concomitant Na and/or K excretion. To test this hypothesis, seven dogs were allowed to recover from hypocapnia while receiving a low electrolyte diet. Despite negligible changes in Na and K excretion, cum delta net acid excretion was --33 meq during adaptation and +44 meq during recovery. Consequently, plasma [HCO3] fell from 19.2 to 14.2 meq/liter in the former and rose from 13.8 to 19.7 meq/liter in the latter groups; these changes were virtually identical to those observed previously in animals maintained on normal electrolyte intakes. These adaptive changes in renal H+ output appeared to be balanced by parallel changes in phosphate excretion. When phosphate retention was prevented during adaptation with Na remaining available for excretion, retention of H+ was still clearly evident. When both phosphate retention and augmented cation excretion were prevented during adaptation, however, H+ retention was abolished. Nevertheless, plasma [HCO3] still fell from 20.9 to 16.2 meq/liter, a level far beyond that attributable to tissue buffering.
D000472:Alkalosis, Respiratory / Q000378:metabolism*; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D002908:Chronic Disease; D004032:Diet; D004285:Dogs; D005260:Female; D006859:Hydrogen / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D012965:Sodium Chloride / Q000378:metabolism
D001639:Bicarbonates; D002712:Chlorides; D010710:Phosphates; D012965:Sodium Chloride; D006859:Hydrogen; D011188:Potassium