title: Reduced nitric oxide-mediated relaxation and endothelial nitric oxide synthase expression in the tail arteries of streptozotocin-induced diabetic rats.
abstract: Diabetes is associated with endothelial dysfunction, which is characterized by impaired endothelium-dependent relaxations. The present study aimed to examine the role of nitric oxide (NO), prostacyclin and endothelium-dependent hyperpolarization (EDH), in the relaxation of ventral tail arteries of rats under diabetic conditions. Relaxations of tail arteries of control and diabetic rats were studied in wire myograph. Western blotting and immunostaining were used to determine the presence of proteins. Acetylcholine-induced relaxations were significantly smaller in arteries of diabetic compared to control rats (Rmax; 70.81 ± 2.48% versus 85.05 ± 3.15%). Incubation with the combination of non-selective cyclooxygenase (COX) inhibitor, indomethacin and potassium channel blockers, TRAM 34 and UCL 1684, demonstrated that NO-mediated relaxation was attenuated significantly in diabetic compared to control rats (Rmax; 48.47 ± 5.84% versus 68.39 ± 6.34%). EDH-type (in the presence of indomethacin and NO synthase inhibitor, LNAME) and prostacyclin-mediated (in the presence of LNAME plus TRAM 34 and UCL 1684) relaxations were not significantly reduced in arteries of diabetic compared to control rats [Rmax: (EDH; 17.81 ± 6.74% versus 34.16 ± 4.59%) (prostacyclin; 15.85 ± 3.27% versus 17.23 ± 3.75%)]. Endothelium-independent relaxations to sodium nitroprusside, salbutamol and prostacyclin were comparable in the two types of preparations. Western blotting and immunostaining indicated that diabetes diminished the expression of endothelial NO synthase (eNOS), while increasing those of COX-1 and COX-2. Thus, since acetylcholine-induced NO-mediated relaxation was impaired in diabetes because of reduced eNOS protein expression, pharmacological intervention improving NO bioavailability could be useful in the management of diabetic endothelial dysfunction.
authors.affiliation: Pharmacology Vascular Laboratory, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, Kota Bharu, Malaysia.
authors.forename: Siti Safiah
authors.initials: SS
authors.lastname: Mokhtar
authors.affiliation: Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Vanhoutte
authors.affiliation: Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: Susan Wai Sum
authors.initials: SW
authors.lastname: Leung
authors.affiliation: School of Health Sciences, Universiti Sains Malaysia, Health Campus, Kota Bharu, Malaysia.
authors.forename: Rapeah
authors.initials: R
authors.lastname: Suppian
authors.affiliation: Department of Orthopaedic, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, Kota Bharu, Malaysia.
authors.forename: Mohd Imran
authors.initials: MI
authors.lastname: Yusof
authors.affiliation: Pharmacology Vascular Laboratory, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, Kota Bharu, Malaysia. Electronic address: aidakb@usm.my.
authors.forename: Aida Hanum Ghulam
authors.initials: AH
authors.lastname: Rasool
mesh_terms: D000818:Animals; D001158:Arteries / Q000187:drug effects / Q000503:physiopathology*; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D000242:Cyclic AMP / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D011464:Epoprostenol / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D010656:Phenylephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D044006:Receptors, Epoprostenol / Q000378:metabolism; D013623:Tail / Q000098:blood supply*; D014664:Vasodilation / Q000187:drug effects
chemical_list: D001786:Blood Glucose; D044006:Receptors, Epoprostenol; D010656:Phenylephrine; D009569:Nitric Oxide; D011189:Potassium Chloride; D011464:Epoprostenol; D000242:Cyclic AMP; D052250:Nitric Oxide Synthase Type III; D006152:Cyclic GMP
keywords: Acetylcholine hydrochloride (PubChem CID: 6060); Diabetes; Indomethacin (PubChem CID: 3715); Ketamine hydrochloride (PubChem CID: 15851); L-NAME hydrochloride (PubChem CID: 135193); NO; Phenylephrine hydrochloride (PubChem CID: 5284443); Prostacyclin (PubChem CID: 5282411); Salbutamol hemisulfate (PubChem CID: 39859); Sodium nitroprusside (PubChem CID: 11963622); Streptozotocin (PubChem CID: 29327); Streptozotocin induced; TRAM 34 (PubChem CID: 656734); Tail artery; UCL 1684 (PubChem CID: 656733)