Relation of TXA2 and PGI2 to the difference in hypoxic pulmonary vasoconstriction between different strains of rats

TXB₂ and 6-keto-PGF₁ α levels in arterial and venous plasma of Wistar and Hilltop rats during hypoxia were measured to investigate the roles of TXA₂ and PGI₂ in hypoxic pulmonary vasoconstriction (HPV) and responsiveness difference of pulmonary vessels to hypoxia between different strains of rats. The results showed that PGI₂ might play an important role in maintaining the low resistance in pulmonary circulation of these two strains of rats. Increased TXA₂ during hypoxia may partially mediate HPV in Wistar rats, while augmented PGI₂ during hypoxia may modulate HPV in Wistar rats. This might be the important mechanism responsible for more intensive responsiveness of pulmonary vessels to hypoxia in Hilltop rats than in Wistar rats.