[Analysis of the factors determining the change in cardiac output during administration of catecholamines]

Electromagnetic flow metering was used in acute experiments on cats to study the cardiac output (CO) and venous return (VR) changes under pressor reactions in response to noradrenaline (NA) and adrenaline (A) infusion. The CO increased in 2/3 and decreased in 1/3 of all observations in response to NA infusion. In half of observations, the VR had the same line of changes as the CO. Similar changes in the CO and VR were obtained after A infusion. The blockade of beta- and M-cholinoreceptors did not affect the magnitude of CO changes in response to NA infusion but played a certain role in response to A infusion. The level of the arterial blood pressure under which the increase of the CO in response to NA infusion was mostly recorded has been established.