Pertussis vaccine reduces agonist binding to the rat heart muscarinic receptor and its guanine nucleotide modulation.

The injection of Bordetella pertussis, inactivated by merthiolate, causes a 2-fold increase in the IC50 of carbamylcholine (carbachol) in displacing [3H];-L(-) quinuclidinyl benzilate binding ([3H]QNB) to the receptor. In control animals, 50 microM Gpp(NH)p causes a 6-fold decrease in the affinity of carbachol binding, whereas after vaccination the reduction is only 1.6-fold. After pertussis treatment there is no alteration in the affinity and number of [3H]QNB binding sites of to the muscarinic receptor.