Fig. 6. The effect of propranolol (A,B) and clonidine (C,D) on arterial (Q_a) and venous (Q_v) blood flow to the abdominal skin in non-acclimated (NAc; A,C) and heat-acclimated (HAc; B,D) pigeons at room temperature. HAc pigeons responded to both treatments by an increase in Q_a and a decrease in Q_v (P<0.005). No difference in Q_a—v blood flow was observed in the NAc pigeons (P>0.05). Values are means ± S.E.M. of 7 birds. ^*P<0.05, ^**P<0.005. The asterisks in parentheses indicate a significant difference between Q_a and Q_v values.