Positive inotropic and chronotropic effect of alloimmune sera on isolated mouse atria

Abstract
The effects of alloimmune sera on the contractile tension and frequency of spontaneously beating isolated mouse atria were explored. Immune sera enhanced frequency as well as tension; both effects were blocked by the presence of propranolol. In contrast, pretreatment with 6-OH dopamine potentiated the stimulatory action of immune sera.