Abstract
The effect of changing the extracellular concentration of both Na+ and K+ on the longitudinal muscle of the guinea-pig ileum was studied in the presence and absence of harmaline. A decrease in extracellular Na+ concentration was found to produce a dose-dependent contractile response, which may suggest the existence of a Na-Ca exchange mechanism in this muscle. Harmaline (2 X 10(-4) M) was found to reversibly inhibit this contraction and was also found to selectively block the tonic component of high-K induced contradictions. In view of the fact that harmaline is a non-competitive inhibitor of Ca-induced contractions (Hider et al., Europ. J. Pharmacol., 71, 87, 1981), the action of harmaline was interpreted as being a specific inhibitor of the Na-Ca exchange mechanism, binding specifically to Na+ coordination sites.
| Original language | English |
|---|---|
| Pages (from-to) | 145-50 |
| Number of pages | 6 |
| Journal | Molecular and Cellular Biochemistry |
| Volume | 67 |
| Issue number | 2 |
| Publication status | Published - Jul 1985 |
Keywords
- Alkaloids
- Animals
- Biological Transport, Active
- Calcium
- Female
- Guinea Pigs
- Harmaline
- Ileum
- In Vitro Techniques
- Muscle Contraction
- Muscle, Smooth
- Potassium
- Sodium
- Journal Article