Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: December 10, 1999
Publication Date: March 15, 2000
Citation: Yokoi, K., Hall, C.B., Lukaski, H.C., Uthus, E.O., Nielsen, F.H. 2000. Estimation of body water by bioimpedance spectroscopy (BIS) in rats fed methionine or homocystine [abstract]. The Federation of American Societies for Experimental Biology Journal. 14:A497. Technical Abstract: The effect of sulfur amino acids (SAA) on body water was studied in rats. Ninety-five weanling male Sprague-Dawley rats were separated into 12 groups and fed respectively 3 x 2 x 2 factorially arranged diets: no supplemental SAA, 10 g/kg dl-methionine or 10 g/kg dl-homocystine (HCY); 0 or 7 mg/kg supplemental pyridoxine; 0 or 1 mg/kg supplemental nickel. After 9 weeks feeding, 20 hour-urine was collected with fasting for measurements of creatinine and protein, and then bioimpedance was measured by multifrequency (Hydra ECF/ICF 4200) and single frequency (RJL Systems Model 101) analyzers. Total body water (TBW) was estimated from the single frequency bioimpedance based on the method of Hall et al (Nutr Rep Int 39; 627, 1989). BIS data were fit to the Cole-Cole model. The intracellular (ICW) to extracellular (ECW) water ratio was estimated by numerically solving the equation using the ratio as an unknown variable derived from the Hanai mixture theory. Total body solid (TBS) was estimated as body weight minus TBW. Urinary creatinine excretion was explained by ICW, TBS and 20-h urinary volume (R2 = 0.675). ECW did not add significantly to the model. Rats fed HCY had significantly higher ratio of ICW to ECW, urinary protein loss and relative kidney weight, compared to animals fed no supplemental SAA. These results suggest alterations in body water distribution and kidney function by dietary HCY. BIS is considered a versatile method for the estimation of body water.