Effect of pertussis vaccine on alpha-adrenoceptors of the circulatory system of the rat.

Administration of pertussis vaccine to rats markedly diminished the sensitivity of their vascular alpha 2-adrenoceptors as evidenced by shifts to the right and decreased maximal pressor responses to clonidine and azepexole in pithed rats. No effect was observed on the sensitivity of alpha 1-adrenoceptors as evidenced by the dose-response curve to methoxamine. A slight persistent tachycardia was also produced by the vaccine. A model to explain the effects of the vaccine on the vascular system of the rat is proposed.