Myocardial oxygen transport during leftward shifts of the oxygen dissociation curve by carbamylation or hypothermia.
An isolated dog heart preparation was used to study the effect of left-shifting the O2 dissociation curve by carbamylation or hypothermia. The two interventions had a similar effect on the variables of O2 delivery. There were significant decreases in myocardial O2 consumption, coronary sinus PO2, and O2 extraction. There was no compensatory increase in O2 transport. Coronary flow autoregulation was somewhat blunted by hypothermia but not by carbamylation. We conclude that an increase in hemoglobin-O2 affinity is capable of limiting myocardial O2 delivery and that increases in convective O2 transport play a minor role at best in the coronary adaptation to small decreases in P50.
Kirksville College of Osteopathic Medicine, Missouri 63501.
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Baer
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003326:Coronary Circulation; D003485:Cyanates / Q000494:pharmacology; D004285:Dogs; D005260:Female; D006321:Heart / Q000187:drug effects / Q000502:physiology* / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects; D007035:Hypothermia / Q000378:metabolism / Q000503:physiopathology; D066298:In Vitro Techniques; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption; D010313:Partial Pressure
D003485:Cyanates; C009281:sodium cyanate; D010100:Oxygen