Dopamine induces contraction in the proximal, but relaxation in the distal rat isolated small intestine

Timo Kirschstein, Fabian Dammann, Jenny Klostermann, Mirko Rehberg, Tursonjan Tokay, Rudolf Schubert, Rüdiger Köhling

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

In the gut, dopamine is released by enteric neurons and modulates motility of small intestine smooth muscle cells. Here, we systematically analyzed the dopamine-induced effects on the longitudinal smooth muscle of different sections of the rat isolated small intestine. We found that exogenous dopamine had biphasic effects and could lead to both an early contraction and a late relaxation, depending on the region of small intestine. Thus, dopamine-induced early contractions were commonly observed in the duodenum, but less frequently in the jejunum, and rarely in the ileum. The amplitudes of these early contractions showed a striking regional dependence (duodenum > jejunum > ileum) and were significantly blocked by SCH23390 and raclopride. Conversely, dopamine-induced late relaxations were regularly obtained in the ileum and in the jejunum, but less frequently in the duodenum. Interestingly, the amplitudes of these relaxations showed an inverse regional dependence (ileum > jejunum > duodenum), and were insensitive to dopamine receptor antagonists. Rather, they were significantly inhibited by propranolol and prazosin. We conclude that dopamine exerts differential effects on smooth muscle motility in different regions within the rat small intestine. In proximal parts, dopamine predominantly causes D1 and D2 dopamine receptor-dependent contraction, whereas it leads to α and β adrenoceptor-dependent relaxation in more distal parts.

Original languageEnglish
Pages (from-to)21-26
Number of pages6
JournalNeuroscience Letters
Volume465
Issue number1
DOIs
Publication statusPublished - Nov 6 2009

Keywords

  • Adrenoceptor
  • Dopamine receptor
  • Enteric nervous system
  • Smooth muscle

ASJC Scopus subject areas

  • Neuroscience(all)

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