AJP - Renal Physiology, Vol 242, Issue 5 508-F513, Copyright © 1982 by American Physiological Society
Relationship among gluconeogenesis, QO2, and Na+ transport in the perfused rat kidney
P. Silva, R. Hallac, K. Spokes and F. H. Epstein
The relationship among sodium transport (TNa), oxygen consumption (QO2),
and gluconeogenesis was studied in isolated perfused rat kidneys in which
glucose formation was enhanced by providing pyruvate as a substrate and by
prior treatment with methylprednisolone. TNa was increased abruptly by
increasing perfusion pressure as to increase GFR or by lowering the albumin
concentration of a hyperoncotic perfusate as to allow glomerular filtration
to occur. Increases in TNa of 40% were accompanied by little or no increase
in QO2, whereas gluconeogenesis decreased 55-80%. Conversely, a decrease in
perfusion pressure that lowered TNa produced an increase in glucose
formation without a change in QO2. When gluconeogenesis was blocked with
0.15 mM 3-mercaptopicolinate, an inhibitor of phosphoenolpyruvate
carboxykinase, QO2 increased together with TNa as perfusion pressure was
raised. The results suggest that the energy needed for ion transport by the
kidney may under some circumstances be borrowed from nontransport functions
and, therefore, that basal oxygen consumption may vary with the rate of
reabsorptive transport.
