Effects of hypoxia and complement activation on lung hemodynamics and fluid exchanges in unanesthetized goats

The effects of hypoxia and zymosan-activated plasma (ZAP) on lung hemodynamics and fluid exchange were studied in unanesthetized goats. Hypoxia produced a sustained increase in pulmonary arterial pressure (PPA), but had no effect on lung lymph flow and protein content. Following ZAP infusion there was an early phase of leukopenia and marked pulmonary hypertension followed by a phase characterized by a modest increase in the flow of protein-rich lung lymph. When ZAP was infused at a simulated altitude of 4,000 m, there was a further increase in PPA followed by pulmonary vasodilatation, and about 1 h later it was almost back to the control level. No obvious difference in lung lymph flow and protein content was observed between the groups treated with ZAP alone and ZAP plus hypoxia. We conclude that infusion of ZAP into hypoxic animals reduces pulmonary vasoconstriction and that the increase in pulmonary microvascular permeability associated with ZAP is not enhanced by hypoxic conditions occurring at a simulated altitude of 4,000 m.