AIM:To study the effect of hypertensive arteriosclerosis on cerebral blood flow autoregulation (CBFA), and to introduce a new method to measure the lower limit. METHODS:The blood velocities and blood pressure was recorded simultaneously and the curves of CBFA were analyzed and classified into classical and non-classical pattern. The lower limit were determined by clinical closing pressure (CCP) and the curve CBFA. RESULTS:When the blood pressure was decreasing, the classical and non-classical pattern of the cerebral blood flow autoregulation were 25% and 75% respectively in normal SD rats, while they were 40.55% and 54.45% respectively in renovascular hypertensive rats (RHR). However, when the blood pressure was elevating, the classical and non-classical pattern were 76.47% and 23.53% respectively in SD rats, while they were all classical in RHR. Furthermore, in SD and RHR ras, the lower limits measured by CCP were well in accordance with that measured by CBFA. CONCLUSION:Hypertensive arteriosclerosis could influence the limits and the patterns of cerebral blood flow autoregulation. The lower limit of CBFA can be measured and analyzed by CCP.

Objective 　To establish a new practical method to assess the cerebral blood flow autoregulation. Methods　We assessed the flow velociey of middle cerebral artery with transcranial Doppler and recorded invasively the blood presure simultaneonsly. Then on the basis of critical closing pressure (CCP), the lower limit of cerebral blood flow autoregulation and the blood flow resistance of arterioles were calculated.The data compared with the results generated by routine method. Results　The lower limit of autoregulation working out by CCP was 70.88±24.05 mmHg, which was similar to the result measured by routine method. The lower limit of autoregulation and the arteriole resistance in RHR were significantly higher than those of normal controls, and highly relate to arterial blood pressure significantly, especially pulse pressure. Conclusions　The physiology and pathology of cerebral blood flow can be evaluated conveniently and accurately by assessment of the lower limit of autoregulation and arterioles resistance with CCP.

AIM: To study the effect of hypertensive arteriosclerosis on cerebral blood flow autoregulation (CBFA), and to introduce a new method to measure the lower limit. METHODS: The blood velocities and blood pressure was recorded simultaneously and the curves of CBFA were analyzed and classified into classical and non-classical pattern. The lower limit were determined by clinical closing pressure (CCP) and the curve CBFA. RESULTS: When the blood pressure was decreasing, the classical and non-classical pattern of the cerebral blood flow autoregulation were 25% and 75% respectively in normal SD rats, while they were 40.55% and 54.45% respectively in renovascular hypertensive rats (RHR). However, when the blood pressure was elevating, the classical and non-classical pattern were 76.47% and 23.53% respectively in SD rats, while they were all classical in RHR. Furthermore, in SD and RHR ras, the lower limits measured by CCP were well in accordance with that measured by CBFA. CONCLUSION: Hypertensive arteriosclerosis could influence the limits and the patterns of cerebral blood flow autoregulation. The lower limit of CBFA can be measured and analyzed by CCP.