| Abstract: | Sera from alloimmunized mice exert potent inotropic and chronotropic effects on mouse isolated atria. In this report, we present data showing that both total immunoglobulins and purified IgG from alloimmunized mice were able to exert per se these effects. The pharmacologic effects of IgG were parallel to its cytotoxic titer but not to its immunofluorescence titer. The specificity of the inotropic and chronotropic effects was studied by using several interstrain immunizations and target atria. It was observed that only the sera from mice immunized with H-2-disparate cells were able to exert pharmacologic effects on atria; these effects were evident not only on atria from the immunizing strain, but also on atria from other strains having identical H-2 but different backgrounds. Neither normal sera nor sera from animals immunized against non-H-2 differences were active. The effect of sera, total immunoglobulins, and purified IgG were blocked by propranolol, suggesting the involvement of beta-adrenoreceptor in the reaction. |
