Effect of the inhalation of nitric oxide on 5-hydroxytryptamine-induced pulmonary hypertension in calves

In healthy anaesthetized Friesian-Holstein calves, pulmonary hypertension was induced ly means of a continuous intravenous administration of serotonin (0.025 mg/kg body/weight/min). Afterwards, the anaesthetized calves inhaled 40 and 80 ppm of nitric oxide using an open system. The influences of the administration of serotonin and the inhalation of nitric oxide on the haemodynamic and blood gas parameters were investigated. The inhalation of 40 and 80 ppm of nitric oxide during: serotonin-induced pulmonary hypertension in calves resulted in a significant fall of the mean pulmonary artery pressure. The inhalation of nitric oxide also induced an amelioration of intrapulmonary oxygen transport. The intravenous administration of serotonin in calves resulted in severe systemic hypotension. Hence, the influence of the inhalation of nitric oxide on the systemic arterial pressure could not be evaluated.