AJP - Regulatory, Integrative and Comparative Physiology, Vol 271, Issue 2 381-R387, Copyright © 1996 by American Physiological Society
Alkali therapy extends the period of survival during hypoxia: studies in rats
F. A. Halperin, S. Cheema-Dhadli, C. B. Chen and M. L. Halperin
Renal Division, St. Michael's Hospital, University of Toronto, Ontario, Canada.
The goal of this study was to evaluate whether sodium bicarbonate might be
a useful form of therapy for hypoxic L-lactic acidosis; our aim was to
determine if alkali could extend the time of survival in this setting.
Hypoxia was induced in anesthetized, paralyzed, artificially ventilated
rats by lowering inspired O2 to 5.5%, an amount sufficient to develop a
severe degree of L-lactic acidosis. Measuring arterial blood gases
frequently permitted maintenance of a near-constant arterial O2 content.
Three groups of hypoxic rats were studied: first, no infusions (n = 10);
second, sodium bicarbonate at a rate equal to H+ production in the
no-infusion group (n = 12); and third, a control for the Na load in the
second group as NaCl (n = 17). Survival was close to twofold longer in the
sodium bicarbonate group. Part of this beneficial effect seemed to be
increased anaerobic glycolysis, producing ATP along with L-lactic acid. In
addition, there was a large decrease in the metabolic demand (consumption
of O2) in the 7- to 15-min period in the sodium bicarbonate group. Rats
exposed to hypoxia and infused with NaCl for 15 min or alkali for 15, 27,
or 40 min were then returned to room air; all survived for the subsequent
experimental period of 150 min. We found that there is both a rationale and
experimental evidence for giving sodium bicarbonate to prolong survival
during hypoxia.
