Hemodynamic effects of prostaglandins and catecholamines in graded reduction of pulmonary flow during venoarterial bypass in awake goats

The roles of prostaglandins and catecholamines in the hypotensive hemodynam ic change during cardiopulmonary support with a venoarterial bypass (VAB) w ere investigated in a series of chronic animal experiments of gradually red uced pulmonary arterial blood flow (PAF). The VAB system consisted of a pul satile ventricular assist device, an artificial lung, and the right atrium uptake and descending aorta return cannulae in four adult goats weighing 49 -51 kg. The PAF was adjusted to 50, 10, and 0% of the total systemic blood flow. Indomethacin, an inhibitor of prostaglandin production; phentolamine, an alpha-antagonist of catecholamine; and noradrenaline, an agonist of cat echolamine were administered at each PAF condition. The mean aortic pressur e (mAoP) and the systemic vascular resistance decreased in proportion to th e decrease in PAF. Indomethacin increased the mAoP at all PAF conditions, i ndicating a relationship between prostaglandins and hypotension. Phentolami ne decreased the mAoP at all PAF conditions, indicating a normal response o f catecholamine receptors. However, noradrenaline increased the mAoP at 50 and 10% PAF, but did not appreciably increase the value at 0% PAF, indicati ng complete response of catecholamine receptors to endogenous catecholamine s at 0% PAF only. In conclusion, prostaglandins play a substantial role in hypotension during VAB, and catecholamines may subsequently increase in com pensation for extreme hypotension.