Effect of inhibiting the sarcoplasmic reticulum on spontaneous and oxytocin-induced contractions of human myometrium
| Autor: | M. J. M. Luckas, Susan Wray, Sajeera Kupittayanant |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
Adult
medicine.medical_specialty Indoles chemistry.chemical_element Calcium Oxytocin Ryanodine receptor 2 Calcium in biology Uterine Contraction Pregnancy Caffeine Internal medicine medicine Humans Enzyme Inhibitors Calcium metabolism Dose-Response Relationship Drug Voltage-dependent calcium channel Ryanodine Ryanodine receptor business.industry T-type calcium channel Obstetrics and Gynecology Sarcoplasmic Reticulum Endocrinology chemistry Female Calcium Channels business Calcium-induced calcium release |
| Zdroj: | BJOG: An International Journal of Obstetrics and Gynaecology. 109:289-296 |
| ISSN: | 1471-0528 1470-0328 |
| Popis: | Objective 1. To assess the contribution of the sarcoplasmic reticulum calcium store in the generation of uterine smooth muscle contractions; 2. to evaluate the contribution of calcium induced calcium release or ryanodine gated calcium channels to myometrial force production. Design Laboratory scientific study. Methods Myometrial strips were obtained from women undergoing elective prelabour caesarean section at term. These were loaded with the calcium sensitive indicator Indo-1 allowing simultaneous assessment of intracellular calcium concentrations and force production. The effect of exposing the strips to ryanodine (which abolishes calcium induced calcium release), caffeine (which activates calcium induced calcium release) and cyclopiazonic acid (which abolishes the sarcoplasmic *reticulum calcium store) was examined. Results Exposure to ryanodine had no appreciable effect on either the amplitude or the duration of the myometrial calcium and force transients but did increase the frequency of contractions (139 ± 5%). Caffeine did not potentiate force. Cyclopiazonic acid increased frequency, duration and amplitude of both calcium and force transients. The ability of oxytocin to provoke calcium and force transients in the absence of extracellular calcium was abolished by cyclopiazonic acid but not by ryanodine. Conclusions These results demonstrate that calcium induced calcium release does not play a significant role in human myometrium and that no functioning role for the ryanodine receptors in human myometrial tissue could be shown. These data suggest that the sarcoplasmic reticulum may act to limit contractions and act as a calcium sink, rather than to amplify contractions. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Plný text