L-Glutamine Metabolism Is Not A Major Source Of Increased Free Radical Generation In Goldblatt Renovascular Hypertension

Abstract

Glutamine has been implicated in the generation of free radicals and free radicals-induced impairment of vascular responses to nitrovasodilators may underlie the pathogenesis of vasospasm in 2K-1C hypertension. Plasma glutamine levels were therefore determined in 2K-1C and 1K-1C hypertensive rats in order to ascertain the direction of change of this amino acid in this model of renovascular hypertension. Hypertension was induced in male SD rats (99±2.3 g) by subjecting them to left renal artery clamping using a 0.2mm silver clip (2K-1C, n=7) under ether anesthesia. Control rats (n=7) were sham-operated (Sh-Op). Rats with 1K-1C hypertension (n=8) and uni-nephrectomized controls (1K:, n=8), additionally underwent right nephrectomy. 10 weeks (2K-1C) and 4 weeks (1K-1C) respectively after renal artery clamping, clipped rats exhibited elevated blood pressures (P<0.001), which was sustained under anaesthesia. No significant difference in plasma glutamine levels were found in hypertensive rats compared to controls (11.3±1.3 mg/l in 2K-1C vs. 12.3±2.1 mg/l in Sh-Op, n=7 and 9.0±1.4 mg/l in 1K-1C vs. 9.6±1.4 mg/l in 1K:, n=8). Serum creatinine and. serum electrolyte concentrations were not significantly different in clipped rats compared to their respective controls. This study shows that plasma glutamine level is not altered in the established stages of Goldblatt renovascular hypertension. The significance of this observation is unclear. Nevertheless, these findings suggest that glutamine is not in the main stream of free radicals generation and is therefore not a reliable index of oxidative stress in this model of renovascular hypertension.

Key words: Glutamine, Glutamate, Superoxide Radicals, Experimental Renovascular Hypertension

Nigerian Journal of Physiological Sciences Vol.18(1-2) 2003: 11-17