[Effect of metoprolol on the flow properties of blood].

In the present article the interaction of 1- isopropylamino-3-[4-(2-methoxyethyl)-phenoxy]-2-propanol (metoprolol, Beloc) with human erythrocytes is reported. Metoprolol is well known and acts mainly as a selective beta-1-antagonist. While erythrocyte aggregation, suspension osmolality and pH-values were unchanged, red cell deformability was markedly improved. Investigation into the furosemide-sensitive fluxes resulted in an inhibition of sodium efflux and in a constant water content of human erythrocytes. These in vitro results suggest that metoprolol induced improvement of red cell deformability cannot be explained by shape changes of erythrocytes.