Adenosine modulation of non-adrenergic non-cholinergic neurotransmission in isolated guinea-pig atria.
Transmural stimulation of non-adrenergic, non-cholinergic sensory nerves in guinea-pig atria, isolated from reserpine-pretreated animals, in the presence of atropine and the beta-adrenoceptor-blocking drug CGP 20712A, induced a positive inotropic effect. Adenosine (0.1-10 microM) concentration-dependently reduced the cardiac response to transmural nerve stimulation, without modifying the response to exogenous calcitonin gene-related peptide; the inhibitory effect of adenosine was antagonized by 1 microM 8-phenyltheophylline. Moreover, the cardiac response to field stimulation was enhanced by 8-phenyltheophylline (0.1, 1 microM) and by adenosine deaminase (1 microgram/ml), but was reduced by dipyridamole (1 microM). These findings indicate the presence of inhibitory adenosine receptors on cardiac sensory nerves and suggest a modulatory effect of endogenous adenosine on cardiac non-adrenergic, non-cholinergic neurotransmission.
Rubino
A
A
Department of Pharmacology, University of Florence, Italy.
Mantelli
L
L
Amerini
S
S
Ledda
F
F
D000241:Adenosine / Q000037:antagonists & inhibitors / Q000502:physiology*; D000243:Adenosine Deaminase / Q000378:metabolism; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology; D004176:Dipyridamole / Q000037:antagonists & inhibitors; D004558:Electric Stimulation; D006168:Guinea Pigs; D006321:Heart / Q000294:innervation*; D006325:Heart Atria / Q000187:drug effects; D007093:Imidazoles / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013806:Theophylline / Q000031:analogs & derivatives / Q000494:pharmacology; D014970:Xanthines / Q000494:pharmacology
D000319:Adrenergic beta-Antagonists; D007093:Imidazoles; D014970:Xanthines; C008514:methylxanthine; D004176:Dipyridamole; D001285:Atropine; D013806:Theophylline; C049763:CGP 20712A; C028322:8-phenyltheophylline; D000243:Adenosine Deaminase; D015740:Calcitonin Gene-Related Peptide; D000241:Adenosine