The effect of isoproterenol on hypoxia-mediated histamine release

In 13 guinea pigs the pulmonary circulation was isolated from the systemic circulation and perfused with Tris buffer alone or with isoproterenol. The lungs were initially ventilated with 100% O2 and then switched to 100% N2 to induce alveolar hypoxia. The effluent was collected from the aorta and assayed for histamine. In the control group (n = 7) the histamine levels rose markedly with hypoxia. In the group perfused with Tris buffer and isoproterenol (n = 6) the rise in histamine levels was markedly diminished. Therefore, the authors conclude that isoproterenol, in their in vivo model, had a dramatic effect on hypoxia (non-immunologic) mediated histamine release.