Interaction between adenosine triphosphate and noradrenaline in the isolated vas deferens of the guinea-pig.
1 An interaction between adenosine triphosphate (ATP) and noradrenaline (NA) was investigated in the isolated vas deferens of the guinea-pig. 2 ATP (1.7 to 50 microM) enhanced contractions due to transmural electrical stimulation (ES; parameters: 30 Hz, 0.2 to 0.3 ms, 10 to 30 V; 1 s train duration). Responses to exogenous NA (12 microM) were also potentiated by ATP while contractions to acetylcholine (6 microM) were inhibited. 3 NA (1.2 microM) potentiated ATP-induced contractions and prevented the development of tachyphylaxis to ATP (510 microM). 4 Phentolamine (12.5 microM) prevented the potentiation by NA of ATP-induced contractions; these contractions were insensitive to phentolamine (up to 25 microM). 5 Removal of potassium chloride from the Tyrode solution for 10 min abolished the potentiating actions of both ATP and NA. 6 The present results suggest that the effect of ATP may be functionally closely related to that of NA at alpha-adrenoceptors in the vas deferens of the guinea-pig.
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology*; D011941:Receptors, Adrenergic / Q000187:drug effects; D009435:Synaptic Transmission / Q000187:drug effects; D014649:Vas Deferens / Q000187:drug effects
D011941:Receptors, Adrenergic; D000255:Adenosine Triphosphate; D009638:Norepinephrine