Effects of Hypertensin on Arterial Pressure, Heart Work and Cardiac Oxygen Utilization

Abstract

Pharmacodynamically induced changes in left ventricular work, using an intravenous infusion of Hypertensin, were studied in intact anesthetized dogs. Coronary and systemic hemodynamics and cardiac metabolism under a combined morphine- "Dial" -urethane-pentobarbital-sodium (MDUP) anesthesia were measured during the action of the drug. The significant hemodynamic changes induced were increased mean arterial pressure and increased left ventricular work. A greater cardiac lactate utilization during the Hypertensin infusion was the only change in cardiac metabolism. The oxygen tension in left ventricular venous blood was not reduced during the action of the drug.

Vasomotor Regulation of Coronary Microcirculation by Oxidative Stress: Role of Arginase

“…However, the vasomotor action of Ang II in the intact heart is controversial. For example, a decrease (39, 40), an increase (41, 42), or a transient decrease followed by an increase (43, 44) in coronary blood flow by Ang II was reported. Although this inconsistency may be a result of using different animal models or experimental approaches, the complexity of flow regulation in the intact heart may be largely responsible for these diverse findings.…”

Primary and Secondary Effects of Angiotensin on the Coronary Circulation

“…Experiments with right bypass circulation in the dog suggested coronary constriction after a small dose of angio tensin and an increase in coronary blood flow after a large dose [12]. Using the same doses in intact dogs Ma x w e l l [13] failed to observe any change, while F o r t e [7] observed an increased cor onary-flow.In the present study different techniques were used to determine the direction and magnitude changes in coronary circulation after administration of angiotensin with the aim of separating direct and indirect effects. Furthermore the coronary effects of angio tensin were analysed in intact dogs before and after the onset of systemic pressor changes.…”

Effects of Norepinephrine and Angiotensin II-amide on Coronary Flow and Myocardial Oxygen Consumption in the Cat

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Animal experiments indicate that both norepinephrine and angiotensin may endanger myocardial oxygen supply: norepi nephrine by inducing a luxury consumption of oxygen (3,6,11,15), angiotensin by causing coronary constriction (4,5,8,9,10,13,16). Although the effects of both substances on coronary flow and on 0.,-metabolism have been thoroughly studied, it is, on the basis of the investigations carried out so far, difficult to decide which mechanism-luxury consumption or coronary con striction-impairs myocardial oxygen supply to a greater extent.

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