Table 1. Fructoselysine content of cells and tissues from Fn3k^+/+ and Fn3k^−/− mice.

Fructoselysine concentration was determined using a radiochemical assay (see Experimental section) in neutralized perchloric acid extracts prepared from washed erythrocytes or the indicated tissues taken from 12–14 month-old mice. Results are means±S.E.M. Figures in parentheses show the number of replicates (n) and the probability. ns, not significant.

		Fructoselysine (μmol/mg of creatinine)
Tissue/cell	Genotype…	Fn3k+/+	Fn3k−/−
Red blood cells		0.28±0.17	3.64±0.25 (n=5; P<0.0001)
Serum		2.87±0.81	2.65±0.76 (n=4; ns)
Brain		0.29±0.07	2.8±0.22 (n=5; P<0.0001)
Kidney		16.4±2.9	22.2±5.5 (n=5; ns)
Heart		0.37±0.13	3.7±1.3 (n=3; P=0.063)
Liver		4.67±1.09	18.8±4.84 (n=3; P<0.05)
Skeletal muscle		2.9±0.79	12.4±0.55 (n=3; P<0.001)