title: NOS upregulation attenuates vascular endothelial dysfunction in the late phase of ischemic preconditioning in skeletal muscle.
abstract: Previously, we have demonstrated a late phase protection of ischemic preconditioning in the microcirculation of cremaster muscle. This microvascular protection was blocked by a non-specific NOS inhibitor. The purpose of present study was to evaluate endothelial function in the terminal arteriole of cremaster muscle after 24-h of ischemic preconditioning followed by 4-h warm ischemia and to evaluate eNOS and iNOS gene and protein expression at 24 h after ischemic preconditioning in the cremaster muscle. A vascular pedicle isolated cremaster muscle in male SD rats underwent 45-min of ischemic preconditioning and 24 h later, 4-h of warm ischemia followed by reperfusion. Endothelial-dependent and -independent vasodilatation was evaluated on day 2 after 4-h ischemia and 60-min of reperfusion. Cremaster muscles were harvested at 24 h after ischemic preconditioning for measuring of eNOS and iNOS gene expression by reverse transcriptase polymerase chain reaction (RT-PCR) and protein expression by western blotting analysis. We found that IPC significantly attenuated endothelial dysfunction induced by 4-h warm ischemia and reperfusion. The expression of eNOS and iNOS mRNA shown a 229% and 135% increase respectively in IPC treated cremaster muscles as compared to normal cremaster muscles (P<0.05). The expression of eNOS and iNOS protein exhibited a 133% and 148% increase respectively in IPC treated cremaster muscles as compared to normal cremaster muscles (P<0.05). There was no statistically significant difference between normal cremaster muscle and sham IPC treated cremaster muscle. The results suggest that IPC preventing vascular endothelial dysfunction from ischemia/reperfusion injury may be due to the enhanced NOS expression. These results combined with the results from our previous studies suggest that IPC-induced microvascular protection in the skeletal muscle may act through a NOS-dependent mechanism.
authors.affiliation: Department of Surgery, University of Nevada School of Medicine, 2040 W. Charleston Boulevard, Suite 301, Las Vegas, NV, USA. wzwang@yahoo.com
authors.forename: Wei Z
authors.initials: WZ
authors.lastname: Wang
authors.forename: Xin-Hua
authors.initials: XH
authors.lastname: Fang
authors.forename: Linda L
authors.initials: LL
authors.lastname: Stepheson
authors.forename: Kayvan T
authors.initials: KT
authors.lastname: Khiabani
authors.forename: Willarm A
authors.initials: WA
authors.lastname: Zamboni
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D042783:Endothelial Cells / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic; D019194:Ischemic Preconditioning; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply*; D019001:Nitric Oxide Synthase / Q000235:genetics* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015854:Up-Regulation
chemical_list: D019001:Nitric Oxide Synthase; D000109:Acetylcholine