Temperature induced peripheral blood flow changes in lizards

Summary

The influence of local temperature changes within the posterior portion of the body on dorsal aorta blood flow ($\dot Q_{da}$), femoral arterial pressure (P _a ), peripheral resistance (R), skin blood flow ($\dot Q_s$) and skeletal muscle blood flow ($\dot Q_m$) was examined in unanesthetized lizards (Iguana iguana andTubinambis nigropunctatus). In response to local heating of the hind legs and tail$\dot Q_{da}$ and$\dot Q_s$ increased,P _a was generally unchanged,R decreased and$\dot Q_m$ decreased or was unchanged (Fig. 2). It is suggested that the acquisition of heat may be favored by diverting the increase in$\dot Q_{da}$ away from the muscle to the warmer skin. In response to cooling$\dot Q_{da}$ and$\dot Q_s$ decreased,P _a was generally unchanged, R increased and$\dot Q_m$ increased or was unchanged. Hence, during cooling the retention of heat may be favored by diverting blood away from the skin to the deeper muscle. The muscle-skin shunt is under sympathetic control since following blockade with phenoxybenzamine HCL (Dibenzyline) muscle blood flow changes in response to temperature were qualitatively similar to those of skin (Fig. 4). These changes in peripheral circulatory patterns are independent of changes in heart rate or deep body temperature.