AJP - Regulatory, Integrative and Comparative Physiology, Vol 255, Issue 1 42-R45, Copyright © 1988 by American Physiological Society
Real importance of alanine in renal metabolism: in vitro studies in rat and dog
G. Lemieux, J. Berkofsky, C. Lemieux, A. Quenneville and M. Marsolais
Renal Laboratory, Hotel-Dieu Hospital, Montreal, Quebec, Canada.
In vitro studies were performed on cortical renal tubules to clarify
possible differences between dog and rat with regard to alanine production
and to define more precisely the role of alanine on ammonia and glucose
production by the kidney. It was established that glutamate-pyruvate
transaminase has an activity that is seven times lower in the rat than in
the dog kidney. At the same time, alanine production from lactate,
pyruvate, and glutamate is three times lower in the rat than in the dog
kidney. The enzymatic reaction could be completely inhibited in a
competitive fashion with aminooxyacetate. O2 consumption and CO2 production
by the renal tubules were lower than that observed with glutamine. CO2
production in the rat was lowest. Production of ammonia and glucose by the
kidney from alanine during acidosis averaged less than 20% of that produced
with L-glutamine. Furthermore, during metabolic acidosis the production of
ammonia and glucose from alanine was not augmented and failed to be
influenced by increasing the concentration of alanine in the incubation
medium.
