Vascular smooth muscle sensitivity to endothelium-derived relaxing factor is different in different arteries.
1. The relaxation responses of pre-constricted pig coronary artery (PCA) and rabbit aorta (RA) without endothelium, to endothelium-derived relaxing factor (EDRF) released from either a PCA or RA with intact endothelium have been studied by use of a bioassay cascade system. Effects of EDRF have been compared with sodium nitroprusside (NaNP) and 8-bromo-cyclic GMP. 2. The time course of changes in cyclic GMP levels in response to EDRF in PCA and RA have also been studied. 3. EDRF (released from a PCA or RA) caused significantly greater relaxation in the PCA than the RA, whether 5-hydroxytryptamine or high extracellular potassium was used as the constrictor agonist. 4. These differences in sensitivity to EDRF were paralleled by NaNP but not 8-bromo-cyclic GMP. 5. Cyclic GMP levels peaked earlier in the RA (30s) than in the PCA (180s) but the peak levels were significantly greater in the PCA (2.45 fold) than the RA (1.48 fold). 6. These data show that the previously described differences in EDRF activity between different artery types can be explained in part by differences in the responsiveness of the smooth muscle to EDRF.
Christie
M I
MI
Department of Pharmacology and Therapeutics, University of Wales College of Medicine, Heath Park, Cardiff.
Lewis
M J
MJ
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000378:metabolism; D001158:Arteries / Q000187:drug effects / Q000378:metabolism; D001685:Biological Factors / Q000494:pharmacology*; D003331:Coronary Vessels / Q000187:drug effects / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D009569:Nitric Oxide; D009599:Nitroprusside / Q000494:pharmacology; D011817:Rabbits; D013552:Swine
D001685:Biological Factors; D009599:Nitroprusside; D015124:8-Bromo Cyclic Adenosine Monophosphate; D009569:Nitric Oxide; D006152:Cyclic GMP