自发性高血压大鼠主动脉压力感受性反射衰减的进一步研究

目的 进一步探讨主动脉压力感受反射中枢性衰减在自发性高血压大鼠（ＳＨＲ）发病中的作用及其发生机制。方法采用６Ｈｚ与６０Ｈｚ两种频率的电方波刺激主动脉神经，观察ＳＨＲ在高血压发生、发展嘛动脉压力感受反射的变化，静注Ｍ受体阻断剂观察其对主动脉压力感受性反射及其衰减的影响。结果 （１）ＳＨＲ收缩压自８周龄起逐渐升高，１６－３２周龄稳定于高血压水平；心率在４周龄时明显加快，左室重／体重比值自４周龄始逐渐升

A Further Study on Attenuation of Aortic Baroreflexin Spontaneously Hypertensive Rats

To study further on the role of central attenuation of aortic baroreflex during the development of hypertension and its mechanism Methods Changes in systolic blood pressure(SBP) and the ratio of LVM /BW were examined during development of hypertension in SHR and age matched WKY rats and the sensitivity of baroreflex was observed simultaneously by electrical stimulation of aortic nerve In the meantime,the effect of vagal blocking with atropine on aortic baroreflex was investigated Results (1)In SHR SBP elevated since the age of 8 wk and hypertension became to be established at the age of 16~32 wk,HR was elevated in SHR at the age of 4 wk,the ratio of LVM/BW was significantly higher in SHR after 4th week (2)Atropine i v decreased the reaction of aortic baroreflex and the difference of HR and MAP effect induced by two frequencies was eliminated completely or in part (3)With BP rising, the aortic baroreflex in SHR assumed progressive attenuation The attenuation of HR response was prior to depressor response and that of responses induced by myelinated fibers was prior to by unmyelinated fibers After atropine i v ,the difference of HR effect between SHR and WKY was eliminated However, difference of MAP effect between 32 week aged SHR and WKY still remained Conclusion The central attenuation of aortic baroreflex plays a role in the development of hypertension In early hypertension,the HR effect attenuation in myelinated fiber originates completely from functional changes in cardiac vagal center The attenuation of MAP effect at later stage can recover the functional changes in sympathetic nerve center ;