Adrenergic influences on histamine-mediated bronchoconstriction in the guinea pig

Abstract

Intravenous infusion of histamine results in a fall in dynamic pulmonary compliance (Cdyn) in the unanesthetized guinea pig. During a prolonged infusion of histamine (30–200 s) a minimum value of Cdyn is reached and sustained after 30 s. Propranolol (10 mg/kg) enhanced this steady-state response in both normal and adrenally ablated guinea pigs to the same degree. After the infusion was terminated, normal guinea pigs recovered briskly, whereas guinea pigs whose adrenals had been ablated recovered slowly. Propranolol prolonged the recovery from the histamine-mediated fall in Cdyn in normal guinea pigs, but had no significant effect on the pattern of recovery in adrenally ablated animals. These experiments suggest that during a histamine infusion nonadrenal adrenergic factors modify the histamine response, but the brisk recovery from histamine is under the influence of adrenal factors.