Alterations of pulmonary vascular resistance and pulmonary cyclic nucleotide metabolism in the hypoxic pig.

Hypoxia leads to an elevation of the pulmonary vascular resistance (pvR) in pigs. This alteration of the hemodynamic was accompanied by a slight increase of intraparenchymatous concentrations of cyclic GMP (cGMP), while cycle AMP (cAMP) levels were not different from values, measured during normoxia. beta-adrenergic agents are potent inhibitors of the hypoxia induced vasoconstriction. This effect was associated with an increase of intraparenchymatous cAMP-concentrations and a decrease of cGMP-levels. The regression analysis between pvR versus the ratio cGMP/cAMP revealed a significant linear correlation. These data may indicate, that cAMP and cGMP are involved in hypoxia induced vasoconstriction and its pharmacological inhibition.