ISSN:
1432-1912
Keywords:
Coronary Blood Fow
;
Regulation
;
Hypoxia
;
Adenosine Release
;
Coronary-Vasodilating Drugs
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary In conscious dogs, blood flow in the circumflex branch of the left coronary artery was measured with electromagnetic flowmeters. Myocardial anoxia followed by reactive hyperemia was produced by occluding the artery with a pneumatic cuff for up to 120 sec. 1. The interval between the beginning and the maximum of reactive hyperemia increased with the duration of occlusion. 2. Independent of the duration of occlusion, the excess flow during reactive hyperemia was 3–4 times as high as the flow deficit during occlusion. 3. Threshold doses of dipyridamole and lidoflazine, while potentiating the dilatation of coronary vessels by adenosine, increased the excess flow only when the arterial occlusion lasted for more than 30 sec. The latter effect was abolished by theophylline. 4. Threshold doses of coronary dilators such as Th 322 and carbochromen which do not potentiate adenosine, did not enhance reactive hyperemia for any duration of occlusion. 5. Theophylline decreased the duration of reactive hyperemia but not the excess flow as expressed by the integral of the strength of hyperemia over time. 6. When infused into the coronary artery, procaine caused a dose-dependent diminution of the reactive hyperemia. The results suggest that appreciable amounts of adenosine are liberated only during complete anoxia for more than 30 sec. Under physiological conditions, coronary resistance is probably regulated by a nervous mechanism and not by the liberation of adenosine.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01422014
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