K+ self-exchange by the Na+ pump: regulation by P(i) and metabolic perturbations.
We have previously demonstrated that the Na(+)-K+ pump on the basolateral membrane of the rabbit cortical collecting duct can function in the K+/K+ exchange mode. Increasing intracellular phosphate in red blood cells inhibits the Na+ pump and increases K+/K+ exchange. We found that maneuvers designed to increase intracellular phosphate in collecting duct cells caused an increase in K+/K+ exchange. Subjecting the cells to a metabolic insult (cyanide) increased K+/K+ exchange by the pump as judged by its ouabain sensitivity and lack of electrogenic or conductive characteristics. The results demonstrate that the rate of K+/K+ exchange by the Na(+)-K+ pump can be altered by changes in intracellular phosphate over a range that is physiologically or pathologically achievable. The results also suggest a mechanism for inhibition of vectorial Na+ transport during metabolic stress.
Nonaka
T
T
Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, USA.
Warden
D H
DH
Matsushita
K
K
Stokes
J B
JB
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D003486:Cyanides / Q000494:pharmacology; D004594:Electrophysiology; D005260:Female; D005947:Glucose / Q000502:physiology; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000378:metabolism*; D007474:Ion Exchange; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D008297:Male; D010710:Phosphates / Q000502:physiology*; D011188:Potassium / Q000378:metabolism*; D011817:Rabbits; D012413:Rubidium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D003486:Cyanides; D010710:Phosphates; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000254:Sodium-Potassium-Exchanging ATPase; D005947:Glucose; D012413:Rubidium; D011188:Potassium