Abstract |
This study tested the hypothesis that aggregation of platelets and release of thromboxane A2 at the site of a coronary arterial stenosis may contribute to myocardial ischemia by impairing flow regulation of the distal coronary bed. Measurements of hemodynamics, flow ( microspheres), lactate metabolism, and prostaglandin (PG) metabolites ( thromboxane B2 and 6-keto-PGF1 alpha) were made in closed-chest anesthetized pigs instrumented with a stenosis (65% diam reduction) in the left anterior descending (LAD) coronary artery. Data were acquired prior to stenosis insertion (control) and 5 and 15 min after insertion, during which time thrombotic occlusion of the device was occurring. Heart rate was controlled by atrial pacing. Distal LAD zone endocardial flow (ml X min-1 X g-1) declined versus control (1.15 +/- 0.20, mean +/- SD) at 5 min (0.89 +/- 0.40, P less than 0.05) and 15 min (0.41 +/- 0.36, P less than 0.01) of occlusion. Distal endocardial resistance (mmHg X ml-1 X min X g), however, did not change versus control (72 +/- 12) at 5 (66 +/- 12) or 15 min (61 +/- 38). Distal epicardial resistance (mmHg X ml-1 X min X g) declined versus control (90 +/- 17) at 5 (66 +/- 35, P less than 0.05) and 15 min (43 +/- 26, P less than 0.01) postinsertion. Finally, lactate extraction (%) at control (42 +/- 19) changed to production 15 min postinsertion (-36 +/- 93, P less than 0.05) and arterial-anterior interventricular vein thromboxane B2 difference (pg/0.1 ml) changed from 13.1 +/- 17.8 pre to -15.8 +/- 30.0 at 5 min post (P less than 0.05). Thus platelet aggregation and release at a spontaneously thrombosing stenosis contribute to ischemia not only by reduction of stenosis diameter but also by impairment of flow regulation in endocardial layers distal to it.
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Authors | H Gewirtz, H Sasken, M Steiner, A S Most |
Journal | The American journal of physiology
(Am J Physiol)
Vol. 249
Issue 6 Pt 2
Pg. H1154-66
(Dec 1985)
ISSN: 0002-9513 [Print] United States |
PMID | 4073284
(Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)
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Chemical References |
- Imidazoles
- Lactates
- Prostaglandin Endoperoxides, Synthetic
- dazmegrel
- Lactic Acid
- Thromboxane A2
- Aspirin
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Topics |
- Animals
- Arterial Occlusive Diseases
(physiopathology)
- Aspirin
(pharmacology)
- Coronary Circulation
- Heart Rate
- Hemodynamics
(drug effects)
- Imidazoles
(pharmacology)
- Lactates
(metabolism)
- Lactic Acid
- Prostaglandin Endoperoxides, Synthetic
(pharmacology)
- Regional Blood Flow
- Swine
- Thrombosis
(physiopathology)
- Thromboxane A2
(biosynthesis)
- Vascular Resistance
- Vasodilation
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