[Preliminary report: effects of artificial blood on hypoxic pulmonary vasoconstriction].

BACKGROUND: We examined the effects of artificial blood on hypoxic pulmonary vasoconstriction (HPV). METHODS: Pump-perfused rabbit lungs were reperfused and ventilated with a mixture of 21% O2, 5% CO2, and balance N2. HPV was induced by reduction of O2 concentration from 21 to 3% for 5 min. Pulmonary arterial pressure (PAP) was measured using a low-pressure transducer. Two perfusion solutions, (1) a mixture of autologous red blood cells and physiological salt solution supplemented with 5% albumin and (2) artificial red blood cells (liposome-encapsulated hemoglobin) and physiological saline supplemented with 5% albumin, were made. Using each solution, HPV was evaluated by PAP increase with and without inhalation of nitric oxide (NO). RESULTS: (1) With both autologous and artificial perfusion solutions, hypoxic stimulation (HS) increased PAP. (2) With the autologous solution, NO inhalation suppressed the HS-induced PAP increase, but with the artificial solutions no such a phenomenon was observed. CONCLUSIONS: NO inhalation failed to suppress HPV with the artificial solution, probably since the liposome-encapsulated hemoglobin strongly inactivated NO.