Hypoxic reptiles: Blood gases, body temperature and control of breathing

Abstract

Our contribution to this symposium is a review of recent models and experimental cdata on oxygen homeostasis in vertebrates with normal intracardiac shunts; i.e., amphibians and reptiles. We focus on the interactions among hemoglobin function, body temperature regulation, and cardiovascular shunts under normal conditions (i.e., breathing fresh air at or near sea level) and during external hypoxia (e.g., altitude, burrows) and internal hypoxia (e.g., anemia, hemorrhage). Mathematical models and experimental data suggest that animals with venous admixture from cardiovascular shunts will show biphasic arterial and mixed venous Po2 responses to warming; i.e., first increasing and then, as the dissociation curve shifts too far to the right, decreasing. This has implications for many physiological functions including oxygen consumption by tissues, control of breathing, as well as preferred body temperature and its regulation. We present some of the recent experiments that have explored these implications. © 1987 by the American Society of Zoologists.