Effect of Anoxia on Mechanical Performance of Isolated Atria from Ground Squirrels and Rats acclimatized to Altitude

Abstract

A FUNCTIONAL adaptation to hypoxia has been described in cardiac tissue from rats acclimatized to altitude¹, but little information is available to explain why hibernating rodents are more tolerant to hypoxia than non-hibernating rodents, even at body temperatures near 37° C (ref. 2). Adaptations which enable hibernators to maintain physiological integrity at body temperatures of 3°–5° C could contribute to survival of severe hypoxia³; this interpretation, however, remains open to question. After exposure to hypoxia, no greater oxygen carrying capacity was found in the blood of a typical hibernator (Citellus lateralis) than in that of the rat⁴. Thus the ability of the hibernator to survive hypoxia could be associated with a functional adaptation to lowered pO₂ at the tissue and/or cellular level.