1 The pharmacological characterization of the 5‐HT3 receptors in guinea‐pig isolated tissues is described. The tissues used were ileum (longitudinal muscle‐myenteric plexus), colon and vagus nerve. The guinea‐pig isolated colon is a novel preparation. 2 In the guinea‐pig isolated ileum, 5‐hydroxytryptamine (5‐HT, 1 × 10−8−3 × 10−5 m) and the selective 5‐HT3 receptor agonist 2‐methyl‐5‐HT (3 × 10−7−1 × 10−4 m) caused concentration‐related contractions. The 5‐HT concentration‐response curve was biphasic whilst the 2‐methyl‐5‐HT curve was monophasic. The EC50 value for the low potency portion of the 5‐HT curve was 4.1 × 10−6 m. The EC50 for 2‐methyl‐5‐HT was 1.23 × 10−5 m. Selective 5‐HT3 receptor antagonists caused rightward shifts of the 2‐methyl‐5‐HT curve and the lower potency portion of the 5‐HT curve. Neither ketanserin (1 × 10−6 m) nor methysergide (1 × 10−5 m) antagonized the responses to 5‐HT or 2‐methyl‐5‐HT. 3 In the guinea‐pig isolated colon, 5‐HT (3 × 10−7−3 × 10−5 m; EC50 2.4 × 10−6 m) caused contractions which were mimicked by 2‐methyl‐5‐HT (1 × 10−6−1 × 10−4 m; EC50 7.2 × 10−6 m). Selective 5‐HT3 receptor antagonists caused rightward displacements of the 5‐HT concentration‐response curves. Neither ketanserin (1 × 10−6 m) nor methysergide (1 × 10−5 m) had any effect on responses to 5‐HT or 2‐methyl‐5‐HT. 4 In the guinea‐pig isolated vagus nerve, 5‐HT (1 × 10−6−3 × 10−4 m) and 2‐methyl‐5‐HT (1 × 10−5−1 × 10−3 m; EC50 7.6 × 10−5 m) caused depolarizations; at higher concentrations there were afterhyperpolarizations. The maximum response to 2‐methyl‐5‐HT was less than half that to 5‐HT. Selective 5‐HT3 receptor antagonists caused rightward displacements of the 5‐HT concentration‐response curves. Antagonists at other 5‐HT receptors (ketanserin, 1 × 10−5 m and methysergide, 1 × 10−6 m) had no effect. 5 The estimated affinity values of 5‐HT3 receptor antagonists correlated well between the three models. Phenylbiguanide was inactive as an agonist or antagonist (up to 1 × 10−4 m) in each preparation. 6 Comparisons with antagonist affinity values obtained in the rat isolated vagus nerve revealed marked differences. Antagonists were generally more potent on the rat isolated vagus nerve, although the differences varied considerably between antagonists. 7 The results are discussed in terms of species‐related receptor differences.
British Journal of Pharmacology – Wiley
Published: Nov 1, 1990
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”
Daniel C.
“Whoa! It’s like Spotify but for academic articles.”
@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”
@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”
@JoseServera
DeepDyve Freelancer | DeepDyve Pro | |
---|---|---|
Price | FREE | $49/month |
Save searches from | ||
Create folders to | ||
Export folders, citations | ||
Read DeepDyve articles | Abstract access only | Unlimited access to over |
20 pages / month | ||
Read and print from thousands of top scholarly journals.
Already have an account? Log in
Bookmark this article. You can see your Bookmarks on your DeepDyve Library.
To save an article, log in first, or sign up for a DeepDyve account if you don’t already have one.
Copy and paste the desired citation format or use the link below to download a file formatted for EndNote
All DeepDyve websites use cookies to improve your online experience. They were placed on your computer when you launched this website. You can change your cookie settings through your browser.