N Angayarkanni1, R Selvam. 1. Department of Medical Biochemistry, Dr. A.L. Mudaliar Postgraduate Institute of Basic Medical Sciences, University of Madras, Taramani, India.
Abstract
OBJECTIVE: To detect the role of the enzyme gamma-glutamyl carboxylase in an experimental stone-forming condition. METHODS: Urolithiasis was induced in experimental rats by (i) oral feeding of 1% ethylene glycol (EG) and (ii) feeding a calculus-producing diet containing 3% sodium glycolate. RESULTS: A significant enhancement in the activity of renal vitamin-K-dependent gamma-glutamyl carboxylase was observed in both groups of experimental urolithic rats. Dicoumarol as well as EG treatment enhanced the accumulation of the endogenous substrate for the enzyme. The carboxylase activity was stimulated by sodium oxalate as well as calcium oxalate in vitro. A positive correlation was observed between lipid peroxidation and the renal gamma-glutamyl carboxylase activity. CONCLUSION: The enhanced carboxylase activity observed in the hyperoxaluric condition is suggested to be due to stimulation of the enzyme by oxalate/calcium oxalate, increased concentration of endogenous carboxylase substrate and lipid peroxidation.
OBJECTIVE: To detect the role of the enzyme gamma-glutamyl carboxylase in an experimental stone-forming condition. METHODS:Urolithiasis was induced in experimental rats by (i) oral feeding of 1% ethylene glycol (EG) and (ii) feeding a calculus-producing diet containing 3% sodium glycolate. RESULTS: A significant enhancement in the activity of renal vitamin-K-dependent gamma-glutamyl carboxylase was observed in both groups of experimental urolithic rats. Dicoumarol as well as EG treatment enhanced the accumulation of the endogenous substrate for the enzyme. The carboxylase activity was stimulated by sodium oxalate as well as calcium oxalate in vitro. A positive correlation was observed between lipid peroxidation and the renal gamma-glutamyl carboxylase activity. CONCLUSION: The enhanced carboxylase activity observed in the hyperoxaluric condition is suggested to be due to stimulation of the enzyme by oxalate/calcium oxalate, increased concentration of endogenous carboxylase substrate and lipid peroxidation.