Open AccessExcitation and Inhibition via Adenosine Receptors of the Twitch Response to Electrical Stimulation in Isolated Guinea Pig Ileum
Author(s) -
Atsushi Tomaru,
Yasuhiro Ina,
Nobuyuki Kishibayashi,
Akira Karasawa
Publication year - 1995
Publication title -
japanese journal of pharmacology/japanese journal of pharmacology
Language(s) - English
Resource type - Journals
eISSN - 1347-3506
pISSN - 0021-5198
DOI - 10.1254/jjp.69.429
Subject(s) - stimulation , guinea pig , ileum , adenosine , chemistry , receptor , biophysics , electric stimulation , medicine , endocrinology , biology , biochemistry
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.