The effect of adenosine triphosphate on the functional status of the ductus arteriosus

We investigated whether a low-dose infusion of ATP-MgCl₂ could affect the functional status of the ductus arteriosus during hypoxia-induced pulmonary vasoconstriction. Three-day-old piglets were mady hypoxic by ventilation with a mixture containing 10% oxygen, 4% CO₂, and balance nitrogen. Serial infusions of ATP-MgCl₂ at 0.1, 0.5, and 1.0 mg/kg/min were compared with preinfusion hypoxia baselines. The functional status of the ductus arteriosus was determined by change in transit time of a bolus of iced saline between thermistor probes in the pulmonary artery and aorta. The method was validated using a Blalock-Taussig shunt (subclavian to pulmonary artery) in 3-week-old piglets instrumented in a similar manner. In these three-day-old piglets, hypoxia alone produced a significant elevation in pulmonary artery pressure and reduction in PO₂. All dose rates of ATP-MgCl₂ produced a significant decrease in mean pulmonary artery pressure. Systemic pressure was significantly decreased only during the 1.0-mg/kg/min infusion. Transit times of a bolus of iced saline during the validation were definitive for characterizing a situation of "shunt open" or "shunt closed". Infusion of ATP-MgCl₂ produced no change in the status of the ductus arteriosus in 45 (94%) of the determinations. In only three cases was the effect of ATP-MgCl₂ sufficient to result in a functional change in the status of the ductus arteriosus. Pre-and postductal pulmonary artery PO₂ were not altered during ATP-MgCl₂ infusion, thus corroborating the transit time determinations. From these results, we conclude that an infusion of ATP-MgCl₂ does not alter the functional status of the ductus arteriosus.