5-Hydroxytryptamine-induced Cl- transport is mediated by 5-HT3 and 5-HT4 receptors in the rat distal colon
Related Experiment Video
Updated: Oct 4, 2026

Gastrointestinal Motility Monitor (GIMM)
Published on: December 1, 2010
M R Budhoo1, R P Harris, J M Kellum
1Department of Surgery, Medical College of Virginia, Richmond 23298, USA.
Abstract:
In the rat distal colon, 5-hydroxytryptamine (5-HT)-induced Cl- secretion is seen as a rise in short circuit current (Isc). We investigated the 5-HT receptor mediating 5-HT-induced Cl- secretion in the rat distal colon. Rat distal colon was prepared either by stripping away the muscularis propria with the neural ganglia, or by leaving it intact. The tissue was mounted in Ussing chambers and short circuited. 5-HT receptor agonist-induced changes (delta) in Isc were recorded in the presence and absence of 5-HT receptor antagonists. In stripped preparations, the rank order of potency of agonists was: 5-HT > 5-methoxytryptamine > alpha-methyl-5-HT >> 2-methyl-5-HT. 5-HT and 5-methoxytryptamine-induced changes in Isc were antagonized by > or = 0.3 microM tropisetron with pA2 values 6.5 and 6.4, respectively. The 5-HT4 antagonist, SC 53606, antagonized the 5-HT-induced response with a pA2 of 7.2. 5-HT1-like (methysergide), 5-HT1P (N-acetyl-5-hydroxytryptophyl 5-hydroxytryptophan amide (5-HTP-DP)), 5-HT2A (ketanserin) and 5-HT3 (ondansetron) receptor antagonists had no significant effect on the 5-HT response in stripped tissue. 3 microM forskolin, or 10 microM 3-isobutyl-1-methyl-xanthine (IBMX), decreased the EC50 and increased the maximum 5-HT response. The 2-methyl-5-HT and 5-HT-induced delta Isc in the unstripped colon preparation were antagonized by the 5-HT3 antagonist, ondansetron (0.3 nM), and 2-methyl-5-HT activity was abolished by pretreatment with tetrodotoxin. In conclusion, 5-HT-induced delta Isc is neurally mediated via a 5-HT3 receptor, and non-neurally mediated via a 5-HT4 receptor in the rat distal colon.
More Related Videos
12:21Thermostabilization, Expression, Purification, and Crystallization of the Human Serotonin Transporter Bound to S-citalopram
Published on: November 27, 2016
11:27Methods to Study Epithelial Transport Protein Function and Expression in Native Intestine and Caco-2 Cells Grown in 3D
Published on: March 16, 2017
Related Concept Videos
The Significance of Membrane Transport
Transporters facilitate either an active or passive movement of solutes. They can allow a single-molecule transport down its...
Membrane Transporters
Transporters are mainly composed of alpha-helices, built from bundles of ten or more helices traversing the plasma membrane. The solute-binding sites are located midway, where some of the helices are broken or distorted, making space for the binding site through...
Transcellular Transport of Solutes
Drug Absorption Mechanism: Carrier-Mediated Membrane Transport
Facilitated diffusion is a passive process that utilizes human Solute Carrier (SLC) transporters. These transporters bind to the drug, undergo structural...
Drugs Affecting GI Tract Motility: Serotonin Receptor Agonists
Carrier-Mediated Transport
Active transport involves two types of membrane-spanning transporters: uptake and efflux. Uptake transporters are expressed in the small...