Oxidant/antioxidant status and endothelial dysfunction in obese and hypertensive models of insulin resistance

ABSTRACT

[1] To investigate the oxidant-antioxidant status and nitric oxide [NO] production in essential hypertensive patients and comparing them to obese normotensive and obese hypertensive patients [2] To compare the NO, antioxidant and oxidants in insulin resistant [IR] patients [fasting glucose insulin ratio [F-G/l ratio] <4.5] versus insulin sensitive [IS] ones [F-G/l ratio > 4.5]. Design: A case control study. Patients Fifty two patients ranging from 30-55 years of age, and classified into Essential hypertensive, non obese patients [group II]; normotensive obese subjects [group III]; and hypertensive obese patients [group IV]. They were further subdivided according to the F.G/I ratio into IR and IS groups. Sixteen age and sex matched healthy subjects [group I] were chosen as controls. Setting: Internal Medicine and Biochemistry Depts., Cairo Medical Hospital. Serum malondialdehyde [MDA] [as a marker for lipid peroxidation], total plasma nitrites and nitrates [Nox] [as an index for NO production], erythrocytic reduced glutathione [GSH], glutathione peroxidase]. [GSH-PX], superoxide dismutase [SOD], and blood vitamin C were estimated by specific colourimetric assays. Plasma selenium was estimated by atomic absorption spectrophotometry. A significant increase mean levels of MDA and reduction in Nox, GSH, vitamin C and, SOD was detected in all patients' groups. Significant reduction in GSH-PX was detected only in the obese groups III and IV. Significant increase in MDA and decrease in Nox, vitamin C and GSH were detected in IR versus IS patients. Simple correlation [r] showed positive relations between MDA and each of MABP, BMI and WHR. Negative correlation was detected between each of Nox, GSH and vitamin C, and each of mean arterial blood pressure [MABP], body mass index [BMI] and waist hip ratio [WHR]. The correlations were higher with WHR than BMI. The F.G/I ratio was negatively correlated with MDA and positively correlated with Nox, GSH and vitamin C. By multiple regression analysis, the WHR was an independent variable concerning F G-I ratio and MABP Activation of lipid peroxidation processes and depression of some antioxidants [especially vitamin C and GSH] proceed more or less in parallel with declining NO bioavailability, the severity of hypertension, extent of obesity, distribution of body fat and degree of IR. The body fat distribution appears to be a more important associate to hypertension and IR than total body fat