Caerulein receptors on the cholinergic neurons in guinea-pig ileum.
The release of [3H]ACh and the contractions of guinea-pig ileal longitudinal muscle preparations, with myenteric plexus attached were measured and recorded simultaneously. Caerulein in concentrations of 10(-11) M to 10(-8) M caused dose-dependent increase of the contractions and the [3H]ACh release. This excitatory effect of caerulein was sensitive to TTX (10(-6) M). Proglumide selectively antagonized both the contractions and the [3H]ACh-releasing effect of caerulein. Electrical field stimulation (O.1 Hz)-evoked contractions were sensitive to atropine. Caerulein (10(-9) M) did not influence the electrically-evoked release of [3H]ACh and the electrically-evoked contractions. Nifedipine (10(-6)M) decreased them about 50%. In the presence of nifedipine caerulein produced an inhibitory effect on the electrically-induced contractions. This nifedipine-unmasking inhibitory effect of caerulein was accompanied by a decrease of the [3H]ACh release and was prevented by proglumide.
Mantovani
P
P
Institute of Pharmacological Sciences, School of Pharmacy, University of Siena, Italy.
Rakovska
A
A
Petkov
V V
VV
De Castiglione
R
R
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D004558:Electric Stimulation; D005260:Female; D006168:Guinea Pigs; D007082:Ileum / Q000294:innervation / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D009197:Myenteric Plexus / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D009543:Nifedipine / Q000494:pharmacology; D010275:Parasympathetic Nervous System / Q000378:metabolism*; D011377:Proglumide / Q000494:pharmacology; D011949:Receptors, Cholecystokinin / Q000187:drug effects / Q000378:metabolism*
D011949:Receptors, Cholecystokinin; D001285:Atropine; D011377:Proglumide; D009543:Nifedipine; D000109:Acetylcholine