Hemodynamic effects of moderate increase of the plasma vasopressin level in conscious dogs

Summary The influence of moderate increase of the plasma ADH level on aortic and central venous pressures, heart rate, cardiac output, stroke volume, central blood volume, systemic peripheral resistance and plasma volume was examined in conscious dogs. The animals were given 0.75 mU ADH/kg b.w. in single intravenous injection as a priming dose. This was followed by a constant infusion of the hormone at a rate of 0,12 mU/min/kg/0.2 ml 0.9% NaCl solution lasting one hour. Plasma ADH level measured at 30 min of the infusion was equal to 22 ± 4 U/ml. A significant increase of aortic (mean systolic and diastolic) and central venous pressures, systemic peripheral resistance and of plasma volume was observed in the course of the infusion. It was accompanied by a decrease of heart rate, cardiac output and central blood volume. Changes of stroke volume were not significant.As the plasma level produced by the infusion was such as that following a moderate nonhypotensive haemorrhage [30], the rôle of the hemodynamic effects of vasopressin in maintenance of the blood pressure and volume in hypovolemia is discussed.