The Effects Of L-Arginine On Vascular Calcification In Rats And The Underlying Mechanism

Objectives:In the present study,we establish the rat vascular calcific models induced by vitamin D₃ and nicotine(P.O) to investigate the possible mechanisms whether which was involved in the regulatory action of L-Arginine(L-Arg) in vascular calcification.Methods1.Reproduction of vascular calcific model:vascular calcification in rats was reproduced by intramuscular injection of vitamin D₃ and intragastric administration of nicotin.2.Experimental grouping:36 SD rats were randomly divided into six groups i.e.the blank control without any treatment(CON),the vascular calcification group treated with intramuscular injection of vitamin D₃ and intragastric administration of nicotin(VDN),the group treated with peritoneal injection of NG-nitro-L-arginine methylester alone(LNA),the group with the same treatments as VDN +LNA(VLN),the group with the same treatments as VDN accompanied by peritoneal injection of 0.1g/kg/d L-arginine(VLA) and the group with the same treatments as VDN accompanied by 0.5g/kg/d L-arginine injection(VHA).3.Analysis:vascular calcification were morphological detected under microscope by using Von Kossa's staining;the activities of alkaline phosphatase(ALP) in plasma and thoracic aorta were verified by using phenyl diphosphate-2-sodium;the total calcium contents in thoracic aorta were calculated by ultraviolet spectrophotometry;nitric oxide(NO) contents in plasma and thoracic aorta were determined by enzymatic method and the expression of core binding factorα1(cbfα1) in thoracic aorta were analyzed by Western-blot.Results1.Vascular calcification model in rats were reproduced successfully:after Von Kossa's staining,multiple black particles in aortic tunica media were detected under microscope in VDN group.Compared with VDN group,the black particles in VHA group were significantly less. 2.The ALP activity and total calcium content were significantly higher than those of CON. And compared with VDN group,the plasma ALP activities in VHA and VLA were reduced by 51.38%(P＜0.01) and 26.75%(P＜0.05) respectively,and the corresponding ALP activities in thoracic aorta were reduced by 59.83%(P＜0.01) and 18.17%(P＜0.05) respectively. Compared with VDN group,the total calcium contents in thoracic aorta were reduced by 38.69%(P＜0.05) and 16.60%(P＜0.05) respectively.3.Copmared with CON,the NO content in plasma and in thoracic aorta were decreased in the VDN and VLN groups(P＜0.05).Whereas compared with VDN group,the NO content in plasma and in thoracic aorta were increased in VLA and VHA groups(P＜0.05).4.Compared with CON,the expression of cbfα1 in thoracic aorta increased significantly in VDN and VLN groups(P＜0.05).And compared with VDN group,the expression of cbfα1 in thoracic aorta decreased significantly in in VLA and VHA groups(P＜0.05).Conclusions1.L-arginine can significantly attenuate the calcification in aorta induced by Vitamin D₃ and nicotine in rats.2.The anti-calcification role of L-arginine may be related to upregulation of NO and downregulation of Cbfα1 expression.