[Changes in the central and peripheral circulation and in the acid-base equilibrium of the blood in dogs during a passive orthostatic test].

Integral changes in circulation and acid-base equilibrium of blood were studied on urethane-chloralose anesthesized dogs during a 20 min tilt test. Against the background of a relatively stable mean pressure in the aorta, the blood flow in the aorta and carotid artery diminished, pressure in the right atrium decreased and the heart rate increased. The phase of isometric contraction of the left ventricle increased, ejection time, mechanical systole and intrasystolic index decreased whereas the myocardial contractility increased. The blood flow in the liver, spleen and hind limb skin reduced and in hind limb muscles remained unaltered. In the arterial blood metabolic acidosis and hyperventilation developed.