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1. 1. The acute systemic and coronary hemodynamic effects of intravenous administration of chlorothiazide are reported in 9 hypertensive subjects. 2. 2. There was a significant decrease in the central venous pressure and pulmonary artery pressure accompanied by decreased cardiac output and reduced right and left ventricular work. 3. 3. Coronary blood flow decreased slightly, but not significantly, and the coronary sinus blood oxygen content was maintained.

1. The systemic and coronary hemodynamic effects of bradykinin have been studied during its infusion into anesthetized dogs. 2. The administration of bradykinin is associated with decreased peripheral, pulmonary, and coronary vascular resistance, accompanied by systemic arterial hypotension. 3. Cardiac output increased, and coronary blood flow increased in those animals with a normal or low resting coronary flow and decreased in those with high resting coronary blood flow. 4. The depletion of catecholamine, through the administration of reserpine, does not change the response basically, although it is modified slightly.

This report describes the program for utilizing a small hybrid computing system to process coronary arterial flow and pressure signals obtained from chronically instrumented, conscious animals and discusses the advantages and disadvantages of the hybrid approach. Extensive analog preprocessing using parallel logic facilitates formation of data during the experiment and minimizes later editing. Moreover, it allows the digital portion of the program to be much smaller and more general than similar applications using only digital systems. Final output consists of an ink-jet recording of the analog signals, a printout of the digital results, and CalComp plots.

In the intact, anesthetized dog, an intravenous infusion of 0.02 U/kg body weight/min of Vasopressin increased the total peripheral, pulmonary, and coronary vascular resistance and decreased coronary blood flow and cardiac output There was a slight increase in systemic arterial blood pressure, A dec

1. 1. Hemodynamic studies, including the determination of cardiac output and coronary blood flow, have been made before and after the intravenous administration of diazoxide to anesthetized intact dogs and unanesthetized man. The response was essentially the same in the dog and in man. 2. 2. Administration of this agent intravenously was accompanied by an acute reduction in peripheral, total pulmonary, and coronary resistances, with a decrease in systemic and pulmonary arterial pressures and an increase in cardiac output and coronary blood flow. 3. 3. Coronary sinus oxygen content increased, with the per cent increase in coronary blood flow significantly greater than the change in cardiac rate, left ventricular work, and left ventricular oxygen consumption. 4. 4. The acute hemodynamic effects of diazoxide in control animals are not significantly different from the effects in animals pretreated with chlorothiazide or small doses of reserpine. 5. 5. Although both diazoxide and chlorothiazide are benzothiadiazine derivatives, their acute hemodynamic effects differ greatly.

Summary1. The acute hemodynamic effects of trimethidinium methosulfate have been studied in 10 mongrel dogs. 2. Administration of the drug results in a decrease in blood pressure in the systemic and pulmonary arteries and the right atrium. 3. Associated with these decreased pressures, the stroke volume decreased, but there was sufficient increase in cardiac rate so that cardiac output did not change significantly. Pulmonary vascular resistance decreased significantly where as peripheral resistance fell slightly but not significantly. 4. Both right and left ventricular work decreased significantly while left ventricular myocardial oxygen consumption was unchanged and calculated cardiac efficiency decreased. 5. These hemodynamic effects are similar to those of hexamethonium, pentolinium, mecamylamine and SKF 6890.

1. 1. Guanethidine was administered intravenously in a dose of 15 mg. per kilogram of body weight to a series of dogs, and hemodynamic studies were performed before and an average of 22 minutes after its administration. 2. 2. Subsequent to administration of guanethidine there was an increase in cardiac rate, hemoglobin, hematocrit, and mean arterial blood pressure in the systemic arteries, pulmonary artery, and right atrium, as well as an increase in cardiac output, coronary blood flow, and left ventricular oxygen consumption. 3. 3. The increase in systemic arterial blood pressure subsequent to the administration of guanethidine was blocked by immediate prior administration of phentolamine, and the elevated pressure which resulted from guanethidine was reduced by the administration of phentolamine. 4. 4. Pretreatment of the dog with reserpine prevented the hypertensive phase of guanethidine action, as well as the usual increase in cardiac output and body oxygen consumption. 5. 5. These results are compatible with an increased sympathetic-like action during the intermediate phase of guanethidine action, and suggest that this phase could be due to the release of catecholamines.

Conclusion1. The systemic and coronary hemodynamic effects of Ascensil®. (2-amino-4-methyl pyridine) also known as RA 1226 and in the German literature as W 45, has been investigated in 10 mongrel dogs. 2. Its administration has been associated with a marked increase in peripheral, pulmonary and coronary vascular resistance accompanied by an increase in peripheral arterial and right atrial pressure. 3. Considerable reduction occurred in cardiac output, coronary blood flow and myocardial oxygen usage per 100 g per minute, subsequent to its administration. 4. Calculated cardiac efficiency, body oxygen consumption, total body respiratory quotient and cardiac respiratory quotients were unchanged.