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Objective: To investigate the arterial baroreflex (ABR)-associated mechanism of losartan in protection of acute cerebral ischemia injury in spontaneously hypertensive rats (SHRs). Methods: Losartan (10 mg·kg -1·d-1) were administered i. g. to SHRs for 2 weeks, and the hemodynamic parameters and the baroreflex sensitivity (BRS) was determined. Then the rats were subjected to middle cerebral arterial (MCA) occlusion to establish acute cerebreal ischemia. The brain samples were obtained, sectioned and stained 24 h later; the infarction area of the brain was measured. Losartan and angiotensin II (Ang II, 100 pmol) were also microinjected into the nucleus of solitary tract (NTS) of rats, and the hemodynamic parameters and BRS were determined 24 h later. Then the rats were subjected to MCA occlusion to establish acute cerebral ischemia injury. The brain infarction area was measured 24 h after operation. Results: Compared to control rats, intragastric administration of losartan improved the ABR function and significantly decreased the infarction area (P<0.05). NTS microinjection of Ang II obviously increased the blood pressure, and decreased BRS value of rats. NTS microinjection of losartan did not change the blood pressure, and significantly improved the ABR function (P<0.05) and alleviated cerebral infarction injury (P<0.05). Conclusion: Losartan can improve the sensitivity of ABR and prevent acute cerebral infarction; NTS might be the target of losartan.
ABSTRACT
AIM: To investigate the changes of vascular systiolic/relaxant function in sino-aortic denervated rats. METHODS: Male Sprague-Dawley rats were underwent sino-aortic denervation (SAD). The sinoaortic denervated (SAD) rats were adopted as a model of arterial baroreflex deficit. SAD, isolated aortic-denervated (AD) and isolated sinus-denervated (SD) rats were instrumented chronically to record blood pressure (BP), heart rate (HR), BP variability (BPV), HR variability (HRV), arterial baroreflex function control of heart period (ABR-HP) and BP (ABR-BP). The vascular maximum contractile/relaxant function was determined through cumulative venous injection of phenylephrine (SBPmax) and nitroprusside(DBPmin) both after ganglionic blokade. RESULTS: Acute SAD(1 week after operation) caused hypertension and tachycardia in rats. Eighteen weeks after operation, BP and HR values in SAD and SD rats were not different from those in sham-operated rats, but AD rats were hypertensive compared with control group. Though the 24 h mean BP values of chronic (18 weeks after operation) SAD rats was not different from those in the sham-operated rats, 24 h BPV of SAD rats was significantly higher when compared with sham-operated rats. ABR function in the acute SAD rats was significantly decreased when compared with sham-operated rats, whereas in chronic SAD rats, both ABR-HP and ABR-BP were higher than those in acute SAD rats, but were still significantly lower than those in control groups. 18 weeks after operation, ABR function in SAD and AD rats were significantly decreased when compared with those in SD and control groups. SBPmax after phenylephrine and DBPmin after nitroprusside were significantly higher in SAD, AD and SD rats than in control group. ABR function was negatively correlated to DBPmin(r = -0.677 for ABR-HP, and r = -0.681 for ABR-BP; P<0.001) and SBPmax(r = -0.614 for. ABR-HP, and r = -0.545 for ABR-BP; P< 0.001) in the whole group of the denervated rats (n = 44). ABR function of the sino-aortic denervated rats was negatively related to the 24 h BPV. CONCLUSION: Remarkable changes of vascular systolic/ relaxant dysfunction are observe in sino-aortic denervated rats 18 weeks after operation, and this effect is closely relate to the decreased ABR function and increase 24 h BPV.
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OBJECTIVE:To observe the effect of Xionggui dripping pills on sensitivity of baroreflex in selective sinoaortic denervated rats.METHODS:The dynamic blood pressures were monitored in selective sinoaortic denervated rats in waking stait,and the changes of baroreflex senitivity(BRS)were measured by modified SU Smyth method.RESULTS:Xionggui drip_ ping pill could improve BRS in sinus denervated rats.CONCLUSION:Since Xionggui dripping pill rectifies autonomic nerve function,it can protect target organs from damage in cardiovascular diseases.
ABSTRACT
AIM To investigate the changes of vascular systiolic/relaxant function in sino-aortic denervated rats. METHODS Male Sprague-Dawley rats were underwent sino-aortic denervation (SAD). The sinoaortic denervated (SAD) rats were adopted as a model of arterial baroreflex deficit. SAD, isolated aortic-denervated (AD) and isolated sinus-denervated (SD) rats were instrumented chronically to record blood pressure (BP), heart rate (HR), BP variability (BPV), HR variability (HRV), arterial baroreflex function control of heart period (ABR-HP) and BP (ABR-BP). The vascular maximum contractile/relaxant function was determined through cumulative venous injection of phenylephrine (SBP max ) and nitroprusside(DBP min ) both after ganglionic blokade. RESULTS Acute SAD(1 week after operation) caused hypertension and tachycardia in rats. Eighteen weeks after operation, BP and HR values in SAD and SD rats were not different from those in sham-operated rats, but AD rats were hypertensive compared with control group. Though the 24 h mean BP values of chronic (18 weeks after operation) SAD rats was not different from those in the sham-operated rats, 24 h BPV of SAD rats was significantly higher when compared with sham-operated rats. ABR function in the acute SAD rats was significantly decreased when compared with sham-operated rats, whereas in chronic SAD rats, both ABR-HP and ABR-BP were higher than those in acute SAD rats, but were still significantly lower than those in control groups. 18 weeks after operation, ABR function in SAD and AD rats were significantly decreased when compared with those in SD and control groups. SBP max after phenylephrine and DBP min after nitroprusside were significantly higher in SAD, AD and SD rats than in control group. ABR function was negatively correlated to DBP min ( r =-0.677 for ABR-HP, and r =-0.681 for ABR-BP; P