Abstract
The mechanisms of sensitization to the lethal effects of histamine induced by B. pertussis vaccine were found to be different from that induced by adrenalectomy. The frequent appearance of cardiac irregularities which occurred several minutes after the histamine injection was a characteristic feature in the vaccinated rats. In the vaccinated rats glucocorticoid did not afford a complete protection against the lethal effect of histamine; the cardiac irregularities remained unchanged. This is in contrast to the resuscitating effect of the corticoid in the adrenalectomized animals. For the induction of cardiac irregularities presence of both adrenal cortex and medulla were found to be necessary. The cardiac irregularities were not due to hyperkalemia.
