title: Activation of protein kinase A improves vascular endothelial dysfunction.
abstract: The study has been designed to investigate the effect of 8-Br-cAMP, an activator of protein kinase A (PKA), in diabetes mellitus- and hyperhomocysteinemia-induced vascular endothelial dysfunction. Streptozotocin (55 mg kg-1, i.v.) and methionine (1.7% w/w, p.o., 4 weeks) were administered to rats to produce diabetes mellitus (serum glucose >200 mg dL-1) and hyperhomocysteinemia (serum homocysteine >10 microM), respectively. Vascular endothelial dysfunction was assessed using isolated aortic ring preparation, electron microscopy of thoracic aorta, and serum concentration of nitrite/nitrate. The expression of mRNA for p22phox and endothelial nitric oxide synthase (eNOS) was assessed by using reverse transcriptase-polymerase chain reaction (TBARS) (RT-PCR). Serum thiobarbituric acid-reactive substances (TBARS) concentration and aortic superoxide anion concentration were estimated to assess oxidative stress. 8-Br-cAMP (5 mg kg-1, i.p.) or atorvastatin (30 mg kg-1, p.o.) prevented diabetes mellitus- and hyperhomocysteinemia-induced attenuation of acetylcholine-induced endothelium-dependent relaxation, impairment of vascular endothelial lining, decrease in expression of mRNA for eNOS, serum nitrite/nitrate concentration, and increase in expression of mRNA for p22phox, superoxide anion, and serum TBARS. The ameliorative effect of 8-Br-cAMP was prevented by N omega-nitro-L-arginine methyl ester (L-NAME) (25 mg kg-1, i.p.) and glibenclamide (5 mg kg-1, i.p.). Therefore, it may be concluded that 8-Br-cAMP-induced activation of PKA may improve vascular endothelial dysfunction.
authors.affiliation: Department of Pharmaceutical Sciences and Drug Research, Faculty of Medicine, Punjabi University, Punjab, India.
authors.forename: Dhvanit I
authors.initials: DI
authors.lastname: Shah
authors.forename: Manjeet
authors.initials: M
authors.lastname: Singh
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology / Q000503:physiopathology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology* / Q000503:physiopathology*; D006710:Homocysteine / Q000097:blood / Q000378:metabolism; D020138:Hyperhomocysteinemia / Q000201:enzymology / Q000503:physiopathology; D008297:Male; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000378:metabolism; D009573:Nitrites / Q000097:blood; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013481:Superoxides / Q000378:metabolism; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
chemical_list: D001786:Blood Glucose; D009573:Nitrites; D012333:RNA, Messenger; D017392:Thiobarbituric Acid Reactive Substances; D006710:Homocysteine; D013481:Superoxides; D015124:8-Bromo Cyclic Adenosine Monophosphate; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; D019255:NADPH Oxidases; C086986:CYBA protein, human; D017868:Cyclic AMP-Dependent Protein Kinases