AJP - Cell Physiology, Vol 259, Issue 4 C660-C667, Copyright © 1990 by American Physiological Society
Glycolytic component of rat spermatid energy and acid-base metabolism
J. G. Reyes, M. V. Velarde, R. Ugarte and D. J. Benos
Instituto de Quimica, Universidad Catolica de Valparaiso, Chile.
The impact of glycolysis on rat spermatid energy metabolism is made
apparent by the simultaneous occurrence of the following three events upon
glucose addition to the extracellular medium of a rat spermatid cell
suspension: decrease in ATP content, exit of acid equivalents, and
increased lactate production and efflux. In this work, we have studied the
interrelations between these three phenomena. By measuring ATP content, net
acid transport, lactate exit, oxygen consumption, intracellular pH, CO2
production, and glycolytic intermediates in the presence of glucose and
glucose analogues, we conclude that 1) lactate production, decrease in ATP
content, and acid equivalent exit are dependent on the metabolism of
glucose up to different stages in glycolysis. 2) The decrease in ATP
content is not directly related to the exit of acid equivalents from rat
spermatids. 3) Glucose metabolism is a net ATP-consuming process at high
intracellular ATP content but is a net ATP-producing process at low
intracellular ATP concentration in rat spermatids. 4) Acid equivalent
production arises from the metabolism of glucose beyond glyceraldehyde
3-phosphate dehydrogenase. 5) Lactic acid diffusion and/or lactate
transport and CO2 production and exit could account for the
glucose-dependent acid equivalent efflux in rat spermatids.
