| Abstract: | In acute experiments on anesthetized cats, intravenous injection of epinephrine and norepinephrine caused different changes of right and left artrial pressures. These shifts mostly (82%) had similar directions: in these experiments, both right and left atrial pressures could be decreased (I group of animals) or increased (II group). The number of animals in these groups was equal. However, in 18% of the experiments, right atrial pressure was decreased, while left atrial pressure was increased. The changes of the left atrial pressure was, as a rule, more significant as compared with right atrial pressure shifts. In the I group of animals, systolic right atrial pressure was not changed, and systolic left atrial pressure was decreased. In the II group of animals, systolic pressure in both atria was augmented. Diastolic pressure was decreased in both atria in all the animals. When the atrial pressures were decreased, the increases of the superior and inferior vena cava flows, venous return and cardiac output were more significant as compared with animals in which the atrial pressures had been elevated. The changes of the superior and inferior vena cava flows were more obvious in animals following epinephrine injection as compared with animals in which norepinephrine was injected. The right atrial pressure returned to the initial level more rapidly than the left atrial pressure, and the time dynamics of the shifts of the right atrial pressure was similar to that of the superior vena cava flow. The temporal changes of the left atrial pressure were identical to the time changes of the cardiac output. We concluded that character of changes of the mean, systolic, and diastolic right and left atrial pressures following catecholamines injections was not correlated with the direction of venous return and cardiac output shifts, and was depending on intracardiac hemodynamics. |
