TEMPERATURE AND CEREBRAL BLOOD-FLOW REGULATION IN THE FRESH-WATER TURTLE, PSEUDEMYS-SCRIPTA

Chemical regulation of cerebral blood flow (CBF) by CO2 has been demon strated in an ectohermic vertebrate (Davies, Am, J. Physiol. 260: R382 , 1991). Cerebrovascular sensitivity to CO2 (Delta CBF/Delta Pa-CO2), a measure of the vascular reactivity of the cerebral blood vessels to CO2, was found to be 0.7 ml.min(-1).100 g(-1).Torr(-1) during normoxia and 3.4 during anoxia in the freshwater turtle, Pseudemys scripta. In the present study, the effect of body temperature on Delta CBF/Delta Pa-CO2 was studied. Delta CBF/Delta Pa-CO2 was not significantly affec ted by body temperature. It was concluded that if Delta CBF/Delta Pa-C O2 remains constant with changes in body temperatures and CBF is contr olled by CO2, CBF should increase with temperature due to the temperat ure-induced increase in Pa-CO2.