Dissociation of increases in cyclic GMP from relaxation of arterial smooth muscle.

Glyceryl trinitrate increased the cyclic GMP content of epinephrine-contracted aortic strips from glyceryl trinitrate-tolerant rats in a dose-dependent manner. Glyceryl trinitrate (.05 millimicron/ml) at a concentration that caused to relaxation of aortas from tolerant animals but a 42.4 3.7% relaxation of control aortas, elevated cyclic GMP levels in both groups approximately 3-fold. The results are not consistent with the hypothesis that cyclic GMP is involved in the relaxation of arterial smooth muscle.