ABSTRACT
AIM: To investigate the role of nitric oxide (NO) in vascular hyporeactivity during prolonged hemorrhagic shock (HS). METHODS: Anesthetized Sprague-Dawley rats (180-220 g) were subjected to HS insult in which they were bled to a mean arterial pressure (MAP) of 40 mmHg (5.33 kPa) and arteriolar reactivity to norepinephrine in spinotrapezius was detected. The constant MAP of 40 mmHg was maintained until vascular hyporeactivity had occurred and then were resuscitated or sacrificed for further analysis. NO synthase (NOS) activity was measured ex vivo by the conversion of [3H]-arginine to [3H]-citrulline in homogenates from heart, lung, liver, spleen, duodunum, skeletal muscle. 24 h survival rates of resuscitated rats were observed with and without administration of aminoguanidine (AG), a selective inducible NOS (iNOS) inhibitor. Mesenteric arteriolar smooth muscle cells (ASMC) were isolated, and the effects of L-arginine (L-Arg) on membrane potential (MP) of ASMC were determined by fluorescent probe and confocal microscopy in the absence and presence of AG. RESULTS: When vascular hyporeactivity occurred, an increase of NOS activity was observed in liver and heart. Resuscitated rats with AG had a higher survival rate compared with that of control. The MP of ASMC was decreased (more negative) immediately following the addition of L-Arg, and the hyperpolarization effects of L-Arg were partially blocked in the presence of AG. CONCLUSION: These results suggest that excessive NO produced in HS is responsible for the occurrence of vascular hyporeactivity in prolonged hemorrhagic shock, and one of the mechanisms of which may be hyperpolarization of ASMC caused by NO.
ABSTRACT
AIM: To evaluate the role of human angiotensin Ⅱ(AngⅡ) type Ⅰ receptor (AT1R) antisense cDNA (ahAT1) on migration of cultured artery smooth muscle cells (VSMCs). METHODS: Two recombinant adenoviral vectors, Ad/CMV. ahAT1 containing full length antisense cDNA targeting to human AT1R mRNA, and Ad/CMV.LacZ containing LacZ called report gene, were constructed by orientation clone technology and homologous recombination, and then were used to transfect VSMCs in vitro. AT1R expression detected by RT-PCR and immunohistochemistry, and migration of VSMCs measured by Boyden's Chamer methods, were compared between transfected and non- transfected VSMCs. RESULTS: Forty-eight hours after Ad/CMV. ahAT1 transfection, the level of AT1R mRNA decreased markedly (50% of control group), and AT1R protein expression was significantly less (P