IgGs and Mabs against the beta2-adrenoreceptor block A-V conduction in mouse hearts: A possible role in the pathogenesis of ventricular arrhythmias.

Autoantibodies against beta-adrenoceptors might be involved in different cardiomyopathic diseases such as idopathic dilated cardiomyopathy, Chagas' disease and ventricular arrhythmias. To study the effects of such antibodies on the whole heart, we made use of a new technique allowing the measurement of Ca++ transients as well as action potentials in Langendorff preparations of mouse hearts. Mouse antibodies directed against the second extracellular loop of the beta2-adrenoceptor induced conduction blocks which could be washed away by the beta2-adrenoceptor inverse agonist ICI118,551, confirming the specificity and non-toxicity of these events.