Comparative study of the functional coupling of human chorionic gonadotropin and ca2+ activated potassium channels on myometrial contractility in different trimesters of pregnancy | ||
| Bulletin of Egyptian Society for Physiological Sciences | ||
| Article 17, Volume 26, Issue 2, December 2006, Pages 269-282 PDF (279.94 K) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/besps.2006.37573 | ||
| Authors | ||
| Zeinab Alrefaie* 1; Lobna Kassem2; Nahed Salah-Aldin2 | ||
| 1Lecturer, Department of Physiology, Kasr Al Aini - Faculty of Medicine, Cairo University | ||
| 2Assistant Professor, Department of Physiology, Kasr Al Aini - Faculty of Medicine, Cairo University | ||
| Abstract | ||
| Human chorionic gonadotropin, hCG, is central to the regulation of uterine quiescence during pregnancy. The present study was designed to investigate if the relaxant effect of hCG would vary between the different trimesters of pregnancy, whether this effect is linked functionally to the Ca2+ activated potassium channels, BKCa, and if this link would differ between the different stages of pregnancy. Methods: 32 female rats were used in the present study, 8 non-pregnant, 8 pregnant at day 4-5, 8 pregnant at day 11-12 and 8 pregnant at day 20-21, representing the 3 trimesters of pregnancy. Frequency and amplitude of isometric contractions were recorded from uterine strips from each group. These recordings were obtained either from spontaneous contractions, subgroup 1; contractions after addition of 20 iu hCG, subgroup 2; contractions after addition of 10 mM BKCa channels blocker, tetraethyl ammonium TEA, subgroup 3 and contractions after addition of both drugs, subgroup 4. Results: Our results showed that frequency and amplitude of spontaneous uterine contractions were significantly decreased in all trimesters of pregnancy when compared to non-pregnant group. The results also revealed that hCG significantly reduced frequency and amplitude of contraction in all groups and this reduction was more significant in the 2nd and 3rd trimesters of pregnancy. Both parameters of contraction were significantly increased by TEA, while adding both drugs did not alter frequency or amplitude of contraction in both non-pregnant and 1st trimester pregnant strips, but significantly decreased both of them in 2nd and 3rd trimesters pregnant strips. Conclusion: Our findings outlined that hCG exerted a more significant uterorelaxant effect in the late stages of pregnancy and that activation of BKCa channels may explain this relaxant effect. | ||
| Keywords | ||
| Myometrial contraction; rat; human chorionic gonadotropin; calcium activated potassium channels | ||
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