Pertussis toxin does not affect the adenosine-induced inhibition of the efferent function of cardiac capsaicin-sensitive nerves

The negative inotropic effect of adenosine (1-100 microM) was abolished in isolated guinea-pig atria obtained from pertussis toxin-pretreated guinea pigs electrically driven at 4 Hz. However, the inhibitory effect of the same concentrations of adenosine on the cardiac response to stimulation of non-adrenergic non-cholinergic (NANC), capsaicin-sensitive sensory nerves, was not modified by the toxin. These results suggest that, while pertussis toxin-sensitive G proteins are involved in the negative inotropic effect of adenosine, they do not mediate the inhibitory effect of adenosine on cardiac NANC neurotransmission.