Adenylate cyclase activity in heart and lung: effect of epinephrine and histamine in control and sensitized guinea pigs.

The effect of epinephrine and histamine on adenylate cyclase activity in lungs and hearts of control and ovalbumin-sensitized guinea pigs was investigated. Epinephrine at 10(-6) M concentration stimulated adenylate cyclase from both organs of the sensitized animals but had no effect on the enzyme from control tissues. At 10(-4) M, epinephrine stimulated equally the enzyme activity from the control and sensitized lungs and hearts. Histamine, 10(-6) and 10(-4), stimulated equally adenylate cyclase in tissues from both groups of animals. The results suggest that ovalbumin sensitization leads to hypersensitivity of the beta-adrenergic receptors to epinephrine without changing their sensitivity to histamine.