Effect of reserpine pretreatment on avian erythrocyte carbonic anhydrase activation by isoproterenol.

We studied the action of beta-adrenergic agonists on Japanese quail erythrocyte carbonic anhydrase (CA) in vitro. Earlier we had reported that epinephrine increased CA activity by 14%; the present study focused on an attempt to increase the size of this response. Washed erythrocytes from reserpine-treated (1 mg/kg daily i.m. for 3 days) and control birds were incubated for 40 min in the presence of isoproterenol 10(-6) mol/l. The activity of CA expressed as Wilbur-Anderson units/mg hemoglobin was increased by as much as 42% in reserpine-treated birds over the control depending on the conditions. Addition of 10(-5) mol/l of the beta-adrenergic antagonist propranolol inhibited the isoproterenol-induced effect in nonreserpinized birds. We conclude that pretreatment with reserpine, which was accompanied by a fall in plasma catecholamine levels, particularly epinephrine levels, enhanced the activation of CA by isoproterenol.