Relaxant effects of ATP and adenosine on canine large and small coronary arteries in vitro.
Rings from greyhound large (3-4 mm internal diameter) and small (less than 200 microns internal diameter) coronary arteries were mounted in water-jacketed tissue baths or a Mulvany myograph, respectively. Relaxations to ATP and adenosine were determined in arteries precontracted with the thromboxane A2 mimetic U46619 or with K+. ATP was a much more effective relaxant of large arteries than adenosine. ATP relaxed large coronaries by an endothelium-dependent mechanism whereas relaxations to adenosine were not endothelium-dependent. In contrast, adenosine appeared to be slightly more effective than ATP in relaxing small coronary arteries. Moreover, adenosine was more effective in relaxing K+-contracted small coronaries than K+-contracted large coronary arteries. These results suggest that ATP may be a more significant relaxant of large coronaries than adenosine but that adenosine may be a more significant relaxant than ATP in small coronary arteries.
White
T D
TD
Baker Medical Research Institute, Prahran, Victoria, Australia.
Angus
J A
JA
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000241:Adenosine / Q000494:pharmacology*; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D003331:Coronary Vessels / Q000187:drug effects*; D004285:Dogs; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects; D011189:Potassium Chloride / Q000494:pharmacology; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology
D011450:Prostaglandin Endoperoxides, Synthetic; D011189:Potassium Chloride; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000255:Adenosine Triphosphate; D000241:Adenosine