Haemodynamic effects of ATP in dogs during hypoxia-induced pulmonary hypertension

Pulmonary hypertension may result from an increase in vascular resistance c aused by persistent hypoxia. We have investigated the effects of adenosine triphosphate (ATP), administered into the pulmonary artery, on haemodynamic changes occurring in anaesthetized adult dogs subjected to acute hypoxic p ulmonary vasoconstriction. Hypoxia alone (ventilation with 10% O-2/90% N-2) caused significant increases in mean pulmonary arterial blood pressure (PA P), central venous pressure (CVP), and cardiac index (CI) by 71, 102 and 38 %, respectively. ATP (0.03-3.0 mu mol/kg/min approximate to 0.02-1.65 mg/kg /min), when infused under hypoxic conditions, significantly reduced both me an PAP and systemic arterial blood pressure (ABP) in a dose-dependent manne r. The maximum decrease in mean PAP amounted to 20%; mean ABP, on the other hand, was decreased by up to 52% (P < 0.01). Heart rate, CI, CVP and pulmo nary occlusion pressure were not dose-dependently affected by ATP, Our data indicate that while pulmonary arterial administration of ATP in mature dog s during hypoxic pulmonary hypertension causes dilation in the pulmonary va scular bed, it is even more effective in dilating the systemic vasculature. This result suggests a need for further evaluation and warrants cautious u se of ATP in the treatment of hypoxic pulmonary hypertension in adult dogs.