title: [Restraint stress down-regulates L-Arg/NOS/NO pathway of platelet and aortic intima in rats].
abstract: OBJECTIVE
  To investigate alteration and cross link of the aortic intima and platelet endogenous L-Arg/NOS/NO pathway induced by water immersion restraint (WIR) stress.
  
  
  METHODS
  After 7 h of WIR stress, the aortic intima was isolated and prepared the platelet, then NO2- production released from aortic intima and platelet was measured with Greiss regent, NOS activity and L-arginine transport activity were detected by isotope tracer method.
  
  
  RESULTS
  After 7 h of WIR stress, the levels of NO2- from platelet and aortic intima obviously decreased by 57% and 46% respectively as compared with the control rats (P<0.01). The inhibitory effects of NO2- showed a positive correlation between platelet and aortic intima by person regression analysis (r2=0.9835, P<0.01). The kinetics analysis of NOS activity of platelet showed that the enzymatic catalytic maximum velocity (Vmax) decreased by 44%, Km values increase by 18% and the enzymatic catalytic efficiency was obviously reduced in the WIR stress rats (P<0.01). The aortic intima NOS activity was inhibited by 50% after WIR stress (P<0.01). The person analysis showed the obvious correlation between them (r2=0.9726, P<0.01). In the WIR stress platelet, the L-Arg transport Vmax obviously reduced by 32%, Km parameter increased 37%, and the transport efficiency was inhibited by 50% (P<0.01), which exhibited obvious positive correlation with the inhibition of L-Arg transport activity in aortic intima (27%) of WIR stress rats (r2=0.9887, P<0.01).
  
  
  CONCLUSIONS
  WIR stress down-regulated endogenous L-Arg/NOS/NO pathway of aortic intima and platelet, whose alteration showed obvious positive correlation. Detection of the alteration of endogenous L-Arg/NOS/NO pathway in platelet might act as an indirect method to assess the endothelial dysfunction involving the pathogensis of stress.
authors.affiliation: Institute of Cardiovascular Research, Peking University First Hospital, Beijing 100034, China.
authors.forename: Yu-ying
authors.initials: YY
authors.lastname: Cui
authors.forename: Chao-shu
authors.initials: CS
authors.lastname: Tang
authors.forename: Bin
authors.initials: B
authors.lastname: Geng
mesh_terms: D000818:Animals; D001011:Aorta / Q000166:cytology / Q000378:metabolism; D001120:Arginine / Q000378:metabolism*; D001792:Blood Platelets / Q000378:metabolism*; D002478:Cells, Cultured; D015536:Down-Regulation; D042783:Endothelial Cells / Q000378:metabolism; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012149:Restraint, Physical; D015398:Signal Transduction / Q000502:physiology; D013315:Stress, Psychological / Q000503:physiopathology; D017539:Tunica Intima / Q000166:cytology / Q000378:metabolism*
chemical_list: D009569:Nitric Oxide; D001120:Arginine; D019001:Nitric Oxide Synthase