THE BLOOD VOLUMES AND PLASMA PROTEIN DURING LEVARTERENOL-INDUCED HYPERTENSION1

Abstract

An average increase of 56% in mean arterial pressure was associated with an average decrease of 15% in plasma volume (p = 0.01), no change in red cell mass, an average increase of 8% in hematocrit (p = 0.01), and an average increase of 5% in plasma protein (p = 0.05). The protein pool (plasma volume (T-1824) x protein concentration) decreased after the administration of levarterenol from an average of 215 g to 193 g (p = 0.5) which represents an average loss of 22 g or 10% of the plasma proteins. When the calculation of the protein pool is based on indirect measurements of plasma volume (plasma volume equals (red cell mass/hematocrit) minus red cell mass), levarterenol infusion was accompanied by a decrease in protein pool from an average of 155 g to 143 g (12 g or 8%) (p = 0.7). Although the changes in protein pools are not significant (p = 0.5, and p = 0.7), all changes in protein concentrations are in the same direction. The data suggest that the hypertension induced by levarterenol is associated with hemoconcentration. Compared to control determinations, there is an increase in the percentage of packed red cells, the radioactivity per ml of whole blood, the optical density of the T-1824 dyed plasma and in the concentration of plasma protein. The hypertensive state produced by levarterenol is associated with an increase in hematocrit and plasma protein, a decrease in plasma volume, and no change in the red cell mass. The fluid lost during hemoconcentration contains less protein than the plasma.