title: Effects of desensitization to adenosine 5'-triphosphate and adenosine on non-adrenergic inhibitory responses in the circular muscle of rabbit colon.
abstract: An approximate eight fold desensitization of the circular coat of the distal rabbit colon to adenosine 5'-triphosphate (ATP) and adenosine could be achieved by repeatedly exposing the organ to relatively low concentrations (10-100 microM) of these compounds. The desensitization was specific and reversible after prolonged washing. It could be overcome by increasing the concentrations of the purine agonists. Dipyridamole potentiated the non-adrenergic inhibition in response to transmural stimulation but failed to influence the caudad relaxation evoked by radial distension. Desensitization to ATP and adenosine (and to ATP + adenosine simultaneously) did not affect the non-adrenergic inhibition in response to radial distension or transmural stimulation. These results suggest that neither ATP nor adenosine are the final transmitters mediating the non-adrenergic inhibitory responses in the distal colon of the rabbit.
mesh_terms: D000241:Adenosine / Q000494:pharmacology*; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D003106:Colon / Q000187:drug effects* / Q000294:innervation; D004176:Dipyridamole / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D009130:Muscle, Smooth / Q000187:drug effects; D009433:Neural Inhibition / Q000187:drug effects*; D011817:Rabbits
chemical_list: D004176:Dipyridamole; D000255:Adenosine Triphosphate; D000241:Adenosine; D002118:Calcium; D007213:Indomethacin