Abstract
The aim of this study was to examine the contribution of K+ channel activation to β-adrenoceptor-mediated relaxation in rat mesenteric arteries. Isoprenaline and fenoterol concentration-dependently relaxed the phenylephrine-preconstricted endothelium-intact arteries of the rat with EC50 values of 0.26 ± 0.03 μM and 0.87 ± 0.12 μM, respectively. β-Adrenoceptor-mediated relaxation was significantly attenuated upon removal of endothelium. Tetrapentylammonium ions (TPA+) at low concentrations (1-5 μM) inhibited relaxations induced by β-adrenoceptor agonists in arteries with and without endothelium, while glibenclamide (3 μM) had no effect, TPA+ (5 μM) inhibited isoprenaline-induced relaxation in the presence of either iberiotoxin (100 nM) or glibenclamide (3 μM). TPA+ did not alter forskolin-induced relaxation. In the presence of 60 mM extracellular K+, the relaxations induced by two agonists were reduced in endothelium-intact arteries and abolished in endothelium-denuded arteries. The present results suggest that the activation of TPA+-sensitive K+ channels contributes toward the relaxations mediated through β- and β2-adrenoceptor stimulation in rat mesenteric arteries.
| Original language | English |
|---|---|
| Journal | Life Sciences |
| Volume | 62 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 5 Dec 1997 |
| Externally published | Yes |
Bibliographical note
Publication details (e.g. title, author(s), publication statuses and dates) are captured on an “AS IS” and “AS AVAILABLE” basis at the time of record harvesting from the data source. Suggestions for further amendments or supplementary information can be sent to [email protected].Research Keywords
- β-Adrenoceptor-mediated relaxation
- K+ channels
- Mesenteric arteries
- Tetrapentylammonium ions