|
|
||||||||
Original Articles |
Inhaled 5-hydroxytryptamine (5-HT) causes bronchoconstriction in asthmatics, and 5-HT plasma levels are elevated in asthma. Electrical field stimulation (EFS) of human airways, in vitro, evokes cholinergic contraction mediated by the release of acetylcholine (Ach) from postganglionic cholinergic nerves. The present study investigates whether selective 5-HT agonists and antagonists can modulate EFS-induced cholinergic contraction in human airways in vitro. Human airways, obtained from resections for bronchial carcinoma or organ transplant donors, were suspended under 2-g tension, between two platinum wire electrodes, in carbogenated Krebs solution at 37 degrees C and EFS was applied (1-32 Hz, 50 V, 0.5 ms, 15 s every 4 min) to elicit cholinergic contractions. 5-HT (10 microM-0.3 mM) produced frequency- and concentration-dependent facilitation of cholinergic contraction, but did not displace the concentration/response curve to Ach. Tropisetron (1 microM), a 5-HT3 and 5-HT4 antagonist, completely blocked the facilitatory effect of 5-HT (100 microM), whereas both ondansetron (1 microM) and GR 125478D (1 microM), a selective 5-HT3 and 5-HT4 antagonist, respectively, also attenuated the 5-HT-induced enhancement of cholinergic contraction. This facilitatory effect of 5-HT was partially mimicked by both selective 5-HT3 (2-methyl-5-HT) and 5-HT4 (RS 67333 and 5-methoxytryptamine) agonists. Fluoxetine (10 microM), a 5-HT uptake inhibitor, had no effect on the 5-HT (10-100 microm) induced potentiation of cholinergic contraction. These findings suggest that 5-HT facilitates cholinergic contraction in human airways in vitro through stimulation of both prejunctional 5-HT3 and 5-HT4 receptors. This may implicate a role of 5-HT in asthma.
This article has been cited by other articles:
![]() |
M. Yamaguchi, O. Shibata, K. Nishioka, T. Makita, and K. Sumikawa Propofol attenuates ovalbumin-induced smooth muscle contraction of the sensitized rat trachea: inhibition of serotonergic and cholinergic signaling. Anesth. Analg., September 1, 2006; 103(3): 594 - 600. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. F. Perez and M. J. Sanderson The Frequency of Calcium Oscillations Induced by 5-HT, ACH, and KCl Determine the Contraction of Smooth Muscle Cells of Intrapulmonary Bronchioles J. Gen. Physiol., May 31, 2005; 125(6): 535 - 553. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. Lechin, B. van der Dijs, A. E. Lechin, and H. A. Boushey Tianeptine: A New Exploratory Therapy for Asthma Chest, January 1, 2004; 125(1): 348 - 349. [Full Text] [PDF] |
||||
![]() |
F. Lechin and B. van der Dijs Serotonin and Pulmonary Vasoconstriction J Appl Physiol, March 1, 2002; 92(3): 1363 - 1364. [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |