Effects of nitroglycerin on regional O2 supply and O2 consumption in reperfused dog myocardium.
This study was designed to assess whether nitroglycerin would improve the relationship between O2 supply and O2 consumption in the reperfused ischemic dog myocardium. In 16 dogs the left anterior descending coronary artery was occluded for 2 h, followed by a 4 h period of reperfusion. In 8 of the 16 dogs, an infusion of 10 micrograms/kg per min of nitroglycerin was begun 10 min prior and continued during 4 h of reperfusion. Small artery and vein O2 saturations obtained microspectrophotometrically were combined with regional blood flow measurements using radioactive microspheres to determine regional myocardial O2 consumption. In both groups, 2 h of occlusion lowered the regional flow to a similar level. In the control group, 4 h of reperfusion returned the blood flow towards normal levels, from 15 +/- 20 ml/min per 100 g (mean +/- S.D.) at the end of occlusion to 57 +/- 39 in the affected area compared to 84 +/- 32 ml/min per 100 g in the nonischemic area. In nitroglycerin treated animals, the flow increase with reperfusion was similar to the control group (12 +/- 10 to 65 +/- 33 ml/min per 100 g). O2 extraction was greater in the reperfused than in the unaffected area in both groups. However, reperfused region O2 extraction was lower in the nitroglycerin treated than control group. There was a greater number of arteries and veins with reduced O2 saturations in the control group reperfused area compared to the nonischemic area. Nitroglycerin decreased the number of low O2 saturation vessels in the reperfusion area. Reperfusion alone does not restore the ratio of O2 supply to O2 consumption to control values, while nitroglycerin significantly improves this ratio. Thus nitroglycerin appears to better match the increased flow during reperfusion with microregional O2 consumption.
Joselevitz-Goldman
J
J
Department of Physiology and Biophysics, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscatawa 08854-5635.
Acad
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Weiss
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D000818:Animals; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000187:drug effects; D004285:Dogs; D005260:Female; D006321:Heart / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D008297:Male; D008832:Microchemistry; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000378:metabolism*; D005996:Nitroglycerin / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects*
D005996:Nitroglycerin