Hemodynamic structure of antiorthostatic reactions: relationship of mechanical activity of the heart and arterial pressure
Osadchiĭ, L.I.; Balueva, T.V.; Sergeev, I.V.
Aviakosmicheskaia i Ekologicheskaia Meditsina 31(3): 19-23
1997
ISSN/ISBN: 0233-528X PMID: 9244501 Document Number: 475823
In acute experiments with antiorthostatic rats tilt-induced changes in the parameters of cardiac activity (left ventricle systolic pressure (LVPs), its first derivative dp/dt, end-diastolic pressure (EDP) were compared in relation to the directionality and extent of systolic (sAP) and diastolic arterial pressure (dAP) shifts. Rise of the tilt angle by 15-45 degrees reduced sAP and dAP, increased LVPs and EDP and did not influence dp/dt. Changes in the cardiac parameters and AP were not unidirectional; sAP and dAP shifts were asynchronous. In a special experimental series, higher tilt angle was found to bring about opposite changes in cardiac ejection (CE) and total peripheral resistance (TPR). Growth in CE was concurrent to a progressive decline in TPR. Discussed is the response of the vascular system to antiorthostasis the unique character of which is vasodilatation.