Molecular Pharmacology, Vol 12, 688-692, Copyright © 1976 by the American Society for Pharmacology and Experimental Therapeutics

Effects of Stimulant and Relaxant Drugs on Tension and Cyclic Nucleotide Levels in Canine Femoral Artery

¹ Department of Pharmacology, Northwestern University Medical School, Chicago, Illinois 60611

Cyclic nucleotide levels and isometric tension were monitored simultaneously in isolated strips of canine femoral arteries after exposure to various drugs. Phenylephrine (5 µM) produced sustained contractions of the vascular strips but had no significant effect on tissue levels of guanosine 3',5'-cyclic monophosphate or adenosine 3',5'-cyclic monophosphate. Carbachol (100 µM), which had no effect on the tension developed by the arteries, significantly increased tissue levels of cyclic GMP but not of cyclic AMP. Papaverine (100 µM) and nitroglycerin (200 µM) both consistently relaxed phenylephrine-contracted femoral arteries and significantly increased their cyclic GMP levels. Cyclic GMP levels were increased by as much as 73% during papaverine-induced relaxation, and by 1540% during nitroglycerin-induced relaxation. Neither drug had any significant effect on cyclic AMP levels under these conditions. These results are not consistent with the earlier suggestion that contraction and relaxation of vascular smooth muscle are mediated by increases in tissue levels of cyclic GMP and cyclic AMP, respectively.

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