John Oxendine

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We studied the effect of exercise training on the coronary collaterals that developed in response to gradual coronary occlusion in dogs. After their proximal left circumflex coronary artery occlusion, 33 dogs were randomly assigned to exercise or sedentary groups. Coronary collateral function was evaluted 5 weeks or 8 weeks later. The exercised dogs(More)
We investigated the effect that mild coronary stenosis exerts on the ability of the coronary circulation to compensate for the increased extravascular compression that occurs in the subendocardium during tachycardia. An electromagnetic flowmeter transducer and balloon cuff occluder were implanted on the left circumflex coronary artery in seven dogs, and(More)
The effects of separate increases in atrial and ventricular contraction rates on the distribution of coronary flow within the heart were determined in conscious dogs with chronic heart block. Atrial tachycardia increased atrial blood flow and did not change ventricular blood flow. Ventricular tachycardia increased ventricular blood flow but not atrial blood(More)
During prolonged ischemic cardiac arrest successful myocardial protection depends upon uniform delivery of cardioplegic solutions to all regions of the heart. Accordingly, we studied the regional and transmural distribution of a neutral crystalloid (dextran-saline) solution during normothermic (37 degrees C) ischemia in 18 isolated blood-perfused dog hearts(More)
Acute left circumflex coronary artery (LC) occlusion in conscious dogs caused marked ischemia in the myocardium supplied by the occluded artery, as judged by the radioactive microsphere technique for determining blood flow distribution. With the chest open, LC pressure distal to the occlusion fell to 21 +/- 1.9% of aortic pressure. By 8 weeks after gradual(More)
We altered the mechanical activity of the atrial myocardium in open-chest dogs and measured changes in coronary blood flow distribution, using the radioactive microsphere technique. When left and right atrial pressures were decreased to 2 mm Hg by hypovolemia, atrial coronary blood flow fell to values nearly 50% below baseline. Acute left atrial(More)
Thallium-201 and microspheres were injected into the blood simultaneously during left circumflex (LC) occlusion in open chest dogs. The dogs were sacrificed 6-8 minutes later and regional myocardial (201)TI and microsphere concentrations determined. In dogs with permanent LC occlusion the myocardial (201)TI distribution approximated blood flow distribution(More)