ATTENUATION OF EXERCISE-INDUCED MYOCARDIAL-ISCHEMIA IN DOGS WITH RECRUITMENT OF CORONARY VASODILATOR RESERVE BY NIFEDIPINE

被引:83
作者
HEUSCH, G [1 ]
GUTH, BD [1 ]
SEITELBERGER, R [1 ]
ROSS, J [1 ]
机构
[1] UNIV CALIF SAN DIEGO, DEPT MED, DIV CARDIOL, SEAWEED CANYON LAB, M-O13B, LA JOLLA, CA 92093 USA
关键词
D O I
10.1161/01.CIR.75.2.482
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
There is now evidence that under resting conditions coronary vasodilator reserve exists even in the presence of myocardial ischemia. Therefore, we tested the hypothesis that a vasodilator reserve may exist during exercise so that during exercise-induced ischemia a reduction in coronary constrictor tone can be produced that attenuates the decreases in regional myocardial blood flow and function distal to a severe coronary stenosis without changing the determinants of myocardial oxygen demand. Nine dogs were instrumented with an ameroid constrictor on the left circumflex coronary artery and were studied 2 to 3 weeks later. During a control treadmill run, heart rate increased from 119 .+-. 20 to 225 .+-. 20 beats/min and peak left ventricular pressure increased from 144 .+-. 17 to 163 .+-. 28 mm Hg. Poststenotic subendocardial blood flow (measured by a microsphere technique) fell from 1.19 .+-. 0.36 to 0.51 .+-. 0.30 ml/min .cntdot. g and systolic wall thickening (by sonomicrometry) decreased from 24.3 .+-. 5.8% to 6.0 .+-. 6.1%. During an identical run after nifedipine (10 .mu.g/kg iv), systemic hemodynamics were not significantly altered. However, subendocardial blood flow was increased to 0.85 .+-. 0.51 ml/min .cntdot. g (p < .05) and systolic wall thickening to 11.4 .+-. 7.8% (p < .01). We conclude that in this study the amelioration of exercise-induced myocardial ischemia was due to the recruitment by nifedipine of coronary vasodilator reserve.
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页码:482 / 490
页数:9
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