[Study of the role of the venous return in pressor changes in the systemic hemodynamics by the means of the automatic regulation of its value].

Feed-back experiments with catecholamine-induced pressor changes of arterial pressure (AP) aided to study possible contribution of the venous return changes in cats. Preliminary recorded changes were reproduced with the aid of electronic control of perfusion pump connected with extracorporeal reservoir and venous portion of vascular bed. The reproduced changes of venous return corresponded to those occurring under action of catecholamines. The same maximal increase of AP (by 50%) could be obtained by means of increasing the venous return either by 1/6 with adrenaline (A) or by 1/10 with noradrenaline (NA). Maintaining of the increased AP involves to a greater extent participation of the above parameters in systemic shifts; in response to A 1/2 and in response to NA 1/3 of the pressor response can be maintained by an increase in the venous return. The quantitative contribution of the vascular component (total peripheral resistance) to pressor shifts of AP under the catecholamines action is greater than that of the cardiac component, particularly in response to NA.