British Journal of Medicine and Medical Research, ISSN: 2231-0614,Vol.: 3, Issue.: 3 (July-September)
Original Research Article
Comparative Effect of Type 1 and Type 2 Diabetes Mellitus on Vascular Responses of Rat Thoracic Aorta to Potassium Ion Channel Openers
Daniel U. Owu1*, Nelson N. Orie1, Chukwuemeka R. Nwokocha2, Lucie H. Clapp1 and Eme E. Osim3
1BHF Laboratories, Rayne Building, Department of Medicine, University College London, UK.
2Department of Basic Medical Sciences, University of West Indies, Mona Campus, Kingston, Jamaica, West Indies.
3Department of Physiology, College of Medical Sciences, University of Calabar, Calabar, Nigeria.
Background: Diabetes mellitus is associated with many cardiovascular dysfunction and impairment of potassium channel function.
Aim: We compared the vascular reactivity in aorta from streptozotocin-induced and Goto-Kakizaki (GK) diabetic rats to potassium channel openers.
Methodology: Diabetes mellitus (DM) was induced in Sprague Dawley rats by intraperitoneal injection of streptozotocin (STZ) at 65 mg/kg body weight. After four weeks of DM, vascular reactivity of the aortic rings from STZ-induced Sprague Dawley and age-matched GK and control rats to phenylephrine, acetylcholine, levcromakalim and naringenin was studied using standard organ bath procedure.
Results: The phenylephrine-induced contraction was significantly (P<0.05) increased in STZ-diabetic aortic rings [2.03 ±0.07 g] when compared with GK rats [1.47±0.14 g] and STZ-control [1.42±0.21 g]. Maximal relaxation and potency to acetylcholine, levcromakalim and (+/-)-naringenin were significantly (P<0.05) decreased in STZ- diabetic aorta when compared with GK-diabetic and control groups.
Conclusion: The phenylephrine-induced contraction, endothelium-dependent relaxation, KATP - and (+/-)-naringenin-induced vasorelaxation are not altered in the early stages of Type 2 diabetes whereas there is exaggerated contractile response and a relaxant dysfunction involving the endothelium, KATP in Type 1 diabetes mellitus.
Acetylcholine; aorta; Gotto Kakizaki rat; naringenin; potassium channel openers; streptozotocin; vasoconstriction.
Full Article - PDF
DOI : 10.9734/BJMMR/2013/2174