Objective:It has been proposed that blood pressure variability(BPV) is positively related to end-organ damage(EOD) in hypertension.The present work was designed to observe the effects of long-term treatment with nitrendipine and hydralazine on BPV and EOD in spontaneously hypertensive rats(SHR),to examine the hypothesis that lowering BPV with an antihypertensive drug is an important factor in organ protection.Design and methods:Drugs were mixed in rat chow.After 4 months of drug administration,blood pressure was recorded continuously in conscious freely moving rats for 24 h.The heart,kidneys,and brain were then isolated and examined.Results:It was found that nitrendipine significantly decreased blood pressure and BPV,and significantly decreased EOD score in SHR.Hydralazine decreased blood pressure,but did not lower BPV.No effect on EOD was found in hydralazine-treated rats.In control rat(n=38),EOD score was weakly related to systolic blood pressure(r=0.331,P<0.05) and closely related to long-term systolic BPV(r=0.551,P<0.01).In nitrendipine-treated rats,EOD score was closely related to long-term systolic BPV(r=0.602,P<0.01),but not to blood pressure level(r=0.174,P>0.05).Conclusion:BPV plays an important role in the organ-protecting effects of nitrendipine.

AIM: To investigate long-term effects of sinoaortic denervation (SAD) on the contraction and relaxation of thoracic aortae in rats.METHODS:SD rats underwent either SAD or sham operation at the age of 10 weeks. At 4,8, 16, and 32 weeks after operation, the contraction and relaxation of the thoracic aortae were measured by isolated artery technique.RESULTS:The NE-induced contraction and ACh-induced relaxation of aortic rings were progressively increased and depressed respectively after SAD.CONCLUSION:Vascular functional changes induced by purely blood pressure variability is similar to those observed in well-established experimental hypertensive states.