title: The effects of heated vegetable oils on blood pressure in rats.
abstract: OBJECTIVE
  The goal of this study was to determine the possible mechanism that is involved in the blood pressure-raising effect of heated vegetable oils.
  
  
  METHODS
  Adult male Sprague-Dawley rats were divided into 11 groups; the control group was fed with rat chow, and the other groups were fed with chow that was mixed with 15% weight/weight palm or soy oils, which were either in a fresh form or heated once, twice, five, or ten times. Blood pressures were measured at the baseline and throughout the 24-week study. Plasma nitric oxide levels were assessed prior to treatment and at the end of the study. Following 24 weeks, the rats were sacrificed to investigate their vascular reactivity using the thoracic aorta.
  
  
  RESULTS
  Palm and soy oils had no detrimental effects on blood pressure, and they significantly elevated the nitric oxide contents and reduced the contractile responses to phenylephrine. However, trials using palm and soy oils that were repeatedly heated showed an increase in blood pressure, enhanced phenylephrine-induced contractions, reduced acetylcholine- and sodium nitroprusside-induced relaxations relative to the control and rats that were fed fresh vegetable oils.
  
  
  CONCLUSIONS
  The blood pressure-raising effect of the heated vegetable cooking oils is associated with increased vascular reactivity and a reduction in nitric oxide levels. The chronic consumption of heated vegetable oils leads to disturbances in endogenous vascular regulatory substances, such as nitric oxide. The thermal oxidation of the cooking oils promotes the generation of free radicals and may play an important contributory role in the pathogenesis of hypertension in rats.
authors.affiliation: Department of Pharmacology, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia. kamsiah@medic.ukm.my
authors.forename: Kamsiah
authors.initials: K
authors.lastname: Jaarin
authors.forename: Mohd Rais
authors.initials: MR
authors.lastname: Mustafa
authors.forename: Xin-Fang
authors.initials: XF
authors.lastname: Leong
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects*; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000502:physiology; D006358:Hot Temperature; D008297:Male; D009569:Nitric Oxide / Q000032:analysis; D009599:Nitroprusside / Q000494:pharmacology; D000073878:Palm Oil; D010938:Plant Oils / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013024:Soybean Oil / Q000494:pharmacology*; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects
chemical_list: D010938:Plant Oils; D009599:Nitroprusside; D009569:Nitric Oxide; D000073878:Palm Oil; D013024:Soybean Oil; D000109:Acetylcholine