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 muM) was abolished i n isolated guinea-pig atria obtained from pertussis toxin-pretreated g uinea pigs electrically driven at 4 Hz. However, the inhibitory effect of the same concentrations of adenosine on the cardiac response to st imulation of non-adrenergic non-cholinergic (NANC), capsaicin-sensitiv e 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 inhibi tory effect of adenosine on cardiac NANC neurotransmission.