Effects of Irbesartan on ATPase Activity and Angiotensin II in Blood Vessel from Renal Hypertensive Rats

Objective To explore the effects of Irbesartan on activities of Na+-K+-ATPase,Ca2+-ATPase,Angiotensin Ⅱ(Ang Ⅱ)and vascular remodeling in renal hypertensive rats(RHR).Methods Renovascular hypertension was induced by two kidney-one clip method.Eighteen RHR were randomly divided into 3 groups: RHR model group(n=6),Irbesartan treated group [50 mg/(kg·d),n=6],withdrawal group(n=6).Six rats were included in sham operation group.Blood pressure(BP) was measured before and after using irbesartan.Thicknesses of vascular wall(TVW) of thoracic aorta and mesenteric artery were measured after 8 weeks.ATPase activities were determined by enzymatic colorimetric method.Ang Ⅱ level was determined by radioimmunoassay.ResultsCompared to the sham operation group,BP,TVW,Ang Ⅱ of plasma and blood vessel were increased in RHR.The activities of Na+-K+-ATPase,Ca2+-ATPase were decreased in RHR.BP,TVW of mesenteric artery were significantly decreased by irbesartan treatment.An increased Ang Ⅱ level and activity of Ca2+-ATPase in thoracic aorta and mesenteric artery was also found.No change the activity of Na+-K+-ATPase was found after irbesartan treatment.One week after discontinuation of treatment,BP was significantly elevated,the activity of Ca2+-ATPase of thoracic aorta was decreased(both P0.01),There was a significant negative correlation between Ang Ⅱ and the activity of Ca2+-ATPase in RHR.Conclusion The vascular remodeling of RHR may be associated with decreased vascular ATPases activities.Irbesartan can reverse vascular remodeling partially by increasing Ca2+-ATPase activity.