Effects of hypoxia on pulmonary vascular reactions and on lung cGMP and cAMP in pigs.

Abstract Hypoxia leads to an elevation of the pulmonary vascular resistance (pvR) in pigs. This was accompanied by an increase of intraparenchymatous concentrations of cyclic GMP (cGMP), while cyclic AMP (cAMP) levels were not different from values measured during normoxia. The inhibition of the hypoxia-induced vasoconstriction by a β 2 -receptor stimulating agent was associated with a remarkable increase in intraparenchymatous cAMP-concentrations and a decrease in cGMP levels. The correlation analysis between pvR versus the ratio cGMP/cAMP revealed a significant linearity. These data may suggest that cAMP and cGMP are involved in hypoxia induced pulmonary vasoconstriction and its pharmacological inhibition.