Dilatation of coronary stenosis as the salutary effect of nitroglycerin in relief of myocardial ischemia in the dog.
To clarify the role of coronary responses to nitroglycerin (NTG) in relieving myocardial ischemia, we examined the effects of NTG in canine models of dynamic and fixed coronary stenoses. Application of coronary stenosis in the proximal left circumflex artery decreased resting coronary blood flow by approximately 40% and caused a significant depression of left ventricular (LV) dP/dt. During fixed coronary stenosis created with an externally applied constrictor device, intravenous NTG, 5 micrograms/kg, reduced mean aortic pressure by 12 +/- 1.1 mm Hg (mean +/- SEM, p less than 0.01) and coronary blood flow by 9 +/- 1.0% (p less than 0.01) but did not affect stenosis resistance and LV dP/dt. During dynamic coronary stenosis produced with an intraluminal microballoon occluder, intravenous NTG caused a marked increase in coronary blood flow by 40 +/- 8.3% (p less than 0.01) and a decrease in stenosis resistance by 62 +/- 9.3% (p less than 0.01), as compared with postocclusion values, concomitant with a significant improvement in LV dP/dt. Intracoronary infusion of NTG, 1.0 microgram/kg/min, had few systemic and coronary hemodynamic effects during fixed coronary stenosis, whereas intracoronary NTG increased coronary blood flow and reduced stenosis resistance, depending on its dose, during dynamic coronary stenosis. These results indicate that NTG is capable of increasing coronary blood flow and alleviating myocardial ischemia due to direct stenosis-dilating effects related to the vasomobility of the coronary stenosis.
S
S
Sakamoto
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M
Yokoyama
H
H
Fukuzaki
D000284:Administration, Oral; D000818:Animals; D001157:Arterial Occlusive Diseases / Q000188:drug therapy*; D001794:Blood Pressure / Q000187:drug effects; D003331:Coronary Vessels; D004285:Dogs; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D007275:Injections, Intravenous; D008297:Male; D005996:Nitroglycerin / Q000008:administration & dosage / Q000627:therapeutic use*; D013997:Time Factors
D005996:Nitroglycerin