Fig. 3. The effect of propranolol and clonidine on body temperature T_b (A) and cutaneous water evaporation (CWE) (B) in heat-acclimated (HAc; N=8) and non-acclimated (NAc; N=8) pigeons. The decrease in T_b from control values in birds injected with saline (grey bars) following the administration of clonidine (80 µg kg^-1, i.m.; black bars) was stronger than that following propranolol (1.2 mg kg^-1, i.m.; hatched bars), reaching a maximum in HAc animals. The elevation in CWE values 40min after drug administration was much greater in HAc pigeons than in NAc birds. Values are means ± S.E.M. Asterisks denote values significantly different from the control group: ^*P<0.05, ^**P<0.005; daggers denote values significantly different between the HAc and NAc groups: P<0.005.