Cultured rat lung fibroblasts as a model for organic nitrate-induced cyclic GMP accumulation and activation of guanylate cyclase

Cultured rat lung fibroblasts were used as a model to explore the activation of soluble guanylate clyclase by organic nitrates. Addition of organic nitrates resulted in increased cyclic GMP accumulation in intact cells and activation of guanylate cylase in cell-free enzyme preparations. The compounds tested, glyceryl trinitrate, isosorbide dinitrate and the enantiomers of isoidide dinitrate demonstrated different potencies and stereospecificity for cyclic GMP accumulation. Glyceryl trinitrate was the most potent compound followed by D- and L-isoidide dinitrate. Although less potent, L-idoidide dinitrate had a greater maximal response than the D-enantiomer. Isosobide dinitrate was the least potent of the compounds tested. Organic nitrates increased cyclic GMP accumulation at 10 nM, and at 0.2 mM a 70-160 fold increase in cyclic GMP was observed. In cell-free enzyme preparations, stereospecificity was absent and the three dinitrates were equipotent for guanylate cyclase activation, but were less potent than glyceryl trinitrate. The results obtained with cultured rat lung fibroblasts are very similar to those obtained with isolated blood vessels. Thus, these cells represent a simple and sensitive system for assessing the action of organic nitrates on cyclic GMP accumulation and guanylate cyclase activation which appears to be relevant to their action in intact vascular smooth muscle.