Temperature and cerebral blood flow regulation in the freshwater turtle, Pseudemys scripta

Chemical regulation of cerebral blood flow (CBF) by CO2 has been demonstrated in an ectohermic vertebrate (Davies, Am. J. Physiol. 260: R382, 1991). Cerebrovascular sensitivity to CO2 (delta CBF/delta PaCO2), 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 PaCO2 was studied. delta CBF/delta PaCO2 was not significantly affected by body temperature. It was concluded that if delta CBF/delta PaCO2 remains constant with changes in body temperatures and CBF is controlled by CO2, CBF should increase with temperature due to the temperature-induced increase in PaCO2.