Effect of Propranolol on Myocardial Oxygen Consumption and Its Hemodynamic Correlates during Upright Exercise
| Autor: | John E. Vilandre, Fredarick L. Gobel, Frank R. Gams, Yang Wang, Henry Longstreet Taylor, Richard R. Nelson, Kyuhyun Wang, Charles R. Jorgensen |
|---|---|
| Rok vydání: | 1973 |
| Předmět: |
Adult
Male medicine.medical_specialty Physical Exertion Nitrous Oxide Hemodynamics Blood Pressure Propranolol Contractility Oxygen Consumption Heart Rate Coronary Circulation Physiology (medical) Internal medicine Heart rate Humans Medicine Exertion business.industry Myocardium Blood flow Blood pressure Anesthesia Cardiology Cardiology and Cardiovascular Medicine business Beat (music) Blood Flow Velocity medicine.drug |
| Zdroj: | Circulation. 48:1173-1182 |
| ISSN: | 1524-4539 0009-7322 |
| Popis: | Measurements were made of heart rate, aortic blood pressure, systolic ejection period/beat, myocardial blood flow, and myocardial oxygen consumption in nine normal young men during three bouts of upright bicycle exercise: 1) at the workload which produced a heart rate of 120 beats/minute, 2) at the higher workload necessary to produce a heart rate of 120 beats/minute after administration of intravenous propranolol 0.25 mg/kg, and 3) with infusion of propranolol, at the same workload as the first exercise bout. Comparing exercises 1 and 2, we found a much higher workload was required to produce the same heart rate after propranolol. The blood pressure, heart rate-blood pressure product, and myocardial oxygen consumption were the same despite the much greater level of exertion. Comparing exercises 1 and 3, the heart rate, blood pressure, heart rate-blood pressure product, and myocardial oxygen consumption were all significantly lower during exercise 3 after propranolol despite the fact that the same degree of exercise was being done. As in previous studies, the heart rate-blood pressure product was an excellent correlate of myocardial oxygen consumption despite the change in contractility induced by propranolol. The systolic ejection period was prolonged significantly altering the tension-time index (TTI), which became an inadequate index of myocardial oxygen consumption. It is concluded that the heart rate-blood pressure product is a good index of myocardial metabolic needs during exercise and the relationship is undistorted by marked changes in contractility, but the tension-time index is a poor correlate. This data emphasizes the fact that the relative metabolic loads for the whole body and for the heart are determined separately and may not change in parallel with a given intervention. |
| Databáze: | OpenAIRE |
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