title: Excitation and inhibition via adenosine receptors of the twitch response to electrical stimulation in isolated guinea pig ileum.
abstract: The effects of adenosine and its related compounds on the cholinergic twitch response were examined in electrically stimulated guinea pig ileum. Adenosine (3 x 10(-7)-10(-5) M) and an adenosine A1-receptor agonist N6-cyclohexyladenosine (CHA, 10(-8)-10(-6) M) suppressed the twitch. Conversely, the A2a-receptor agonist 2-[p-(2-carboxyethyl)phenethylamino]-5'-N- ethylcarboxamidoadenosine (CGS 21680, 10(-9)-10(-7) M) potentiated the twitch in half the preparations examined. The A1-antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX), which per se did not affect the twitch, recovered the attenuated twitch caused by CHA (10(-7) M) or adenosine (10(-6) M) and converted it into a potentiated twitch. These results suggest the presence of adenosine A1- and A2a-receptors coupled negatively and positively, respectively, to acetylcholine release in the preparation.
authors.affiliation: Department of Pharmacology, Kyowa Hakko Kogyo Co., Ltd., Shizuoka, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Tomaru
authors.forename: Y
authors.initials: Y
authors.lastname: Ina
authors.forename: N
authors.initials: N
authors.lastname: Kishibayashi
authors.forename: A
authors.initials: A
authors.lastname: Karasawa
mesh_terms: D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D002799:Cholinergic Fibers / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects* / Q000502:physiology*; D008297:Male; D018047:Receptors, Purinergic P1 / Q000187:drug effects; D014970:Xanthines / Q000494:pharmacology
chemical_list: D018047:Receptors, Purinergic P1; D014970:Xanthines; D000241:Adenosine