Details

Autor(en) / Beteiligte

• Lombardi, D.M.
• Grous, M.
• Fine, C.F.
• Barone, F.C.
• Fowler, P.J.
• Phyall, W.B.
• Rush, J.A.
• Ormsbee, H.S.

Titel

DA1 receptor mediates dopamine-induced relaxation of opossum lower esophageal sphincter in vitro

Ist Teil von

• Gastroenterology (New York, N.Y. 1943), 1986-09, Vol.91 (3), p.533-539

Ort / Verlag

New York, NY: Elsevier Inc

Erscheinungsjahr

1986

Quelle

MEDLINE

Beschreibungen/Notizen

• The objective of the present experiments was to determine the specific receptor subtype through which dopamine (DA) receptor agonists relax the lower esophageal sphincter in vitro. Opossum lower esophageal sphincter smooth muscle strips were placed in oxygenated Krebs' solution containing propranolol and cocaine. The tissues were placed at a tension that gave maximum relaxation to electrical field stimulation and were then pretreated with phenoxybenzamine. The effects of DA, and the DA receptor agonists epinine and apomorphine were determined. In addition, agonist responses were studied in the presence of the selective DA2 receptor antagonist domperidone, a mixed DA1/DA2 receptor antagonist metoclopramide, and the selective DA1 receptor antagonists bulbocapnine and SK&F 83566. The DA agonists relaxed the smooth muscle strips in the following order of potency: DA > epinine > apomorphine. Domperidone did not antagonize DA- or apomorphine-induced relaxation. Metoclopramide failed to alter DA-induced relaxation. Bulbocapnine and SK&F 83566 significantly inhibited the relaxation induced by DA. These data indicate that DA-induced lower esophageal sphincter relaxation in vitro is mediated by DA1 receptors.