去卵巢对低氧雌性大鼠颏舌肌肌功能的影响

目的检测慢性间歇性低氧雌性大鼠去卵巢后颏舌肌肌功能的变化，探索雌激素影响上气道稳定性的机制。方法40只雌性SD大鼠随机分成4组：正常组、慢性间歇性低氧组、去卵巢组、低氧去卵巢组。手术后第6周，麻醉动物，切断双侧迷走神经，电脉冲刺激舌下神经中央支诱发颏舌肌收缩。原始信号经SMUP—PC型生物信号处理系统输入计算机，使用MFlab功能学实验软件包Version3．00分析，检测各实验动物颏舌肌的等长收缩功能的变化。结果各组间大鼠颏舌肌单刺激收缩、强直收缩最大张力无显著性差异（P〉0．05）；而颏舌肌50％强直收缩时程：低氧组明显低于正常组（P〈0．05），去卵巢组也明显低于正常组（P〈0．05），低氧去卵巢组又较低氧组或去卵巢组明显降低（P〈0．05）。结论慢性间歇性低氧可降低大鼠颏舌肌的抗疲劳性。低氧雌性大鼠去卵巢后颏舌肌肌功能降低。雌激素可能通过增强颏舌肌肌功能的途径对上气道稳定性发挥保护作用。

Effects of ovariectomy on genioglossus function of female rat with chronic intermittent hypoxia

Objective To study the effects of ovariectomy on the muscle function of genioglossus （GG） in chronic intermittent hypoxia （CIH） female rats and explore the possible mechanism of estrogen related with upper airway stability. Methods Forty female Sprague-Dawley （SD） rats were randomly divided into four groups： normal group, CIH group, ovariectomized group, CIH ovariectomized group. Sixth week after surgery, the rats were anesthetized and vagotomized. The contractile characteristics of the whole GG were measured in response to stimulation of hypoglossal medial nerve branch. Data were transferred to SMUP-PC biomedical signal processing system and analyzed by MF lab functional experiment analysis software made in Fudan University. Changes-of isometric contraction of GG were detected in 4 groups. Results No significant change was observed in the isometric twitch tension or tetanic tension among these groups （ P 〉 0.05 ）. Compared to normal group, 50 percent-decay time of tetanic tension significantly decreased in CIH and ovariectomized group （ P 〈 0.05 ）. While a significant decrease was observed in CIH ovariectomized group as compared with CIH group （P 〈 0.05 ）. Conclusion CIH decreases the endurance properties of genioglossus.The genioglossus muscle function in CIH female rat decreases following ovary removal. Estrogen may protect the patency of upper airway through affecting muscle function of upper airway dilator.