Histamine H1, H2 receptor effects on mechanics of ventilation and gas exchange in neonatal calves.

The effect of histamine infusion (IV) on pulmonary mechanical and gas exchange properties of healthy neonatal Holstein-Friesian calves was determined. Histamine increased pulmonary resistance and static pressure-volume hysteresis and decreased dynamic compliance, but failed to change static compliance; changes were compatible with constriction of both large and small airways without a change in lung elasticity. Histamine decreased arterial oxygen tension by increasing the alveolar-arterial oxygen difference, probably because ventilation-perfusion inequalities resulted from small airway constriction. The pulmonary mechanical and gas exchange effects of histamine were prevented by pretreatment with the H1 receptor antagonist, tripelennamine, but not with the H2 receptor antagonist, metiamide. The histamine-induced changes in static pressure-volume hysteresis and dynamic compliance were reversed by sighing, and histamine effects on the lung were eliminated by 15 minutes after cessation of histamine infusion.