1. Excitatory effect of oxytocin on uterine smooth muscle
Experimental pharmacology of reproductive system
Excitatory effect of oxytocin on uterine smooth muscle
Shi-Hong Zhang （张世红） Dept of Pharmacology

2. Uterine stimulants Pituitrin (垂体后叶素) Oxytocin (催产素)
Ergot alkaloids (麦角生物碱)
Prostaglandins (PGs, 前列腺素)

3. Uterine stimulants
Pituitrin(垂体后叶素) 垂体
oxytocin
vasopressin

4. Uterine stimulants Oxytocin (OXT, 催产素) 1. Pharmacological effects:
(1) Uterus:
Elevating both the frequency and force of uterine contraction, at rhythm similar to natural labor, highly dependent on estrogen level and condition of uterus.
(2) Breast: milk ejection.
(3) Blood vessel: vasodilation at large dose.

5. Uterine stimulants Oxytocin (OXT, 催产素) 2. Clinical uses:
-- to expedite delivery and induced labor;
-- to reduce the incidence and severity of postpartum hemorrhage.

6. Uterine stimulants Oxytocin (OXT, 催产素) 3. Adverse effects:
-- Intrauterine asphyxia or uterine rupture (overdose)
-- Allergy
4. Contraindications:
-- hypertonic dysfunction of uterus
-- abnormality in birth canal
-- abnormal fetal position

7. Uterine stimulants
Ergot alkaloids(麦角生物碱) Ergometrine(麦角新碱), Ergotamine(麦角胺), Ergotoxine(麦角毒)
1. Pharmacological effects:
(1) Uterus (ergometrine):
-- strongly stimulating uterine smooth muscle, both the body and the cervix; ready to induce tonic contraction at larger dose .
(2) Blood vessel (ergotamine):
-- contracting peripheral blood vessels and cerebral vessels.
(3) blocking  receptor (ergotoxine):

8. A. Uterine stimulants Ergot alkaloids(麦角生物碱) 2. Clinical uses:
(1) Endometrorrhagia (子宫出血), and puerperal replacement of uterus (产后子宫复位) : ergometrine;
(2) Migraine (偏头痛) : ergotamine;
(3) Hibernation therapy (冬眠疗法) : dihydroergotoxine + pethidine + promethazine.

9. A. Uterine stimulants 3. Adverse effects: Ergot alkaloids(麦角生物碱)
-- nausea, vomiting, BP ;
-- allergic reaction;
-- prohibited in expediting delivery and induced labor.

10. Prostaglandins (PGs, 前列腺素)
Uterine stimulants
Prostaglandins (PGs, 前列腺素)
Dinoprostone (地诺前列酮, PGE2)
Dinoprost (地诺前列素, PGF2)
1. Pharmacological effect:
stimulating uterine smooth muscle.
2. Clinical uses: to induce labor
2. Adverse effects: GI reaction, attack of asthma (PGF2); glaucoma (PGE2).

11. Objectives
To observe the excitatory effect of oxytocin on uterine smooth muscles and its dose dependent manner.

12. Methods
Estrodiol pretreatment (0.2mg) on rats (200 g  40g) 24hr before experiment;
Prepare uterus smooth muscle specimen.

13. Methods
Uterus of the rat

14. Methods
Uterus of the rat

15. Methods
Perfusion system

16. Methods Set parameters of recording system: Input pattern: tensility
Gain:
Lower frequency: direct current
Upper frequency: 10 Hz
Sampling interval: 2 ms
Preload: 1g

17. Methods
The specimen is stabilized in the perfusion chamber for min until the contractive force and rhythm become regular. Record the basal contractive force and frequency (optional).
Add 0.02 ml, 0.04 ml, 0.14 ml oxytocin (0.01U/ml) into the perfusion system. Record the maximal force and frequency (optional) of contraction at each drug concentration accordingly.

18. Methods
Add 0.04 ml, 0.14 ml oxytocin (0.1U/ml) into the perfusion system. Record the maximal force and frequency (optional) of contraction at each drug concentration accordingly.
Add 0.04 ml, 0.14 ml oxytocin (1U/ml) into the perfusion system. Record the maximal force and frequency (optional) of contraction at each drug concentration accordingly.

19. Methods
Add 0.04 ml, 0.14 ml oxytocin (10U/ml) into the perfusion system. Record the maximal force and frequency (optional) of contraction at each drug concentration accordingly.

20. Methods
Notice:
1．Avoid injury and excessive stretch of uterus during the whole process of preparation.
2．Control the gas bubbles in a proper rate in case of impact on uterus contraction.
3．Record a period of baseline of contraction before drug treatment in order to compare that before and after.
4．Add drug in the order as prescribed.

21. Lab report
1．题目 2．署名: 作者和合作者姓名及单位。 3．结构式摘要（目的，方法，结果，结论）。 4．材料和方法: 主要实验材料，标本制备方法，仪器装置连接和仪器参数，实验数据记录条件，观察指标。 5．结果: 实验结果的文字性描述，作量效曲线。 6．讨论: 回答思考题。

22. Learning issue
1．缩宫素对子宫的作用及特点。 2．为什么实验前用雌二醇处理动物？ 3. 缩宫素与麦角新碱对子宫平滑肌的作用特点有何不同？