Association of elevated blood pressure and impaired vasorelaxation in experimental Sprague-Dawley rats fed with heated vegetable oil.
BACKGROUND
Poor control of blood pressure leads to hypertension which is a major risk factor for development of cardiovascular disease. The present study aimed to explore possible mechanisms of elevation in blood pressure following consumption of heated vegetable oil.


METHODS
Forty-two male Sprague-Dawley rats were equally divided into six groups: Group I (control)--normal rat chow, Group II--fresh soy oil, Group III--soy oil heated once, Group IV--soy oil heated twice, Group V--soy oil heated five times, Group VI--soy oil heated ten times. Blood pressure was measured at the baseline level and at a monthly interval for six months. Plasma nitric oxide, heme oxygenase and angiotensin-converting enzyme levels were measured prior to treatment, at month-three and month-six later. At the end of treatment, the rats were sacrificed and thoracic aortas were taken for measurement of vascular reactivity.


RESULTS
Blood pressure increased significantly (p<0.01) in the repeatedly heated oil groups compared to the control and fresh soy oil groups. Consumption of diet containing repeatedly heated oil resulted higher plasma angiotensin-converting enzyme level and lower nitric oxide content and heme oxygenase concentration. Reheated soy oil groups exhibited attenuated relaxation in response to acetylcholine or sodium nitroprusside, and greater contraction to phenylephrine.


CONCLUSIONS
As a result of consumption of repeatedly heated soy oil, an elevation in blood pressure was observed which may be due to the quantitative changes in endothelium dependent and independent factors including enzymes directly involved in the regulation of blood pressure.
Leong
Xin-Fang
XF
Department of Pharmacology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur, Malaysia.
Mustafa
Mohd Rais
MR
Das
Srijit
S
Jaarin
Kamsiah
K
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D002318:Cardiovascular Diseases / Q000517:prevention & control; D004032:Diet / Q000009:adverse effects; D004305:Dose-Response Relationship, Drug; D005511:Food Handling; D006419:Heme Oxygenase (Decyclizing) / Q000097:blood; D006358:Hot Temperature / Q000009:adverse effects*; D006973:Hypertension / Q000097:blood / Q000139:chemically induced* / Q000209:etiology; D066298:In Vitro Techniques; D008054:Lipid Peroxides / Q000008:administration & dosage / Q000633:toxicity*; D008297:Male; D009569:Nitric Oxide / Q000097:blood; D016877:Oxidants / Q000008:administration & dosage / Q000633:toxicity*; D007703:Peptidyl-Dipeptidase A / Q000097:blood; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013024:Soybean Oil / Q000008:administration & dosage / Q000737:chemistry* / Q000633:toxicity; D013997:Time Factors; D014664:Vasodilation / Q000187:drug effects
D008054:Lipid Peroxides; D016877:Oxidants; D009569:Nitric Oxide; D013024:Soybean Oil; D006419:Heme Oxygenase (Decyclizing); C491523:Hmox1 protein, rat; D007703:Peptidyl-Dipeptidase A