Whole-body autoradiographic study of (U-14C) galactose in mice and its biochemical analysis.

Abstract

Tissue and organ distribution and metabolic fate of radioactive carbon from [U-14C] galactose in mice were studied by whole-body autoradiography and biochemical analysis.Autoradiography was performed before and after 6 % perchloric acid treatment at various intervals after intravenous injection of [U-14C] galactose. At 5 min after injection, high radioactivities were observed in the kidney, small intestine and liver.The radioactivities in almost all organs were markedly decreased with the acid treatment.At 30 min after injection, the kidney and small intestine had relatively high radioactivities which were retained by the acid treatment.As for the biochemical analysis, at various intervals after intravenous injection of [U-14C] galactose, the mice were decapitated, and the blood, liver, kidney, small and large intestines, myocardium and brain were removed. These organs were fractionized into 6 % perchloric acid-soluble, -insoluble and lipid parts.Total radioactivity (cpm) per gram of wet weight was the highest in the kidney.The incorporation rates of the radioactivity into the acid-soluble fraction were high in all organs at early intervals, while at late intervals, the rates into the acid-insoluble fraction became relatively high in the kidney, small and large intestines.These results were consistent with those obtained from whole-body autoradiography.Acid-soluble fractions of the blood, kidney, liver and brain were analyzed by paper chromatography.The radioactive spots for galactose and glucose were observed in all organs examined, but the changes of radioactive values with the passage of time were different in each organ.Furthermore, the radioactive spots for RGlucose value 0.28 were detected in these organs.Galactose is C-4 epimer of glucose and is derived from lactose. Ingested lactose is absorbed in the small intestine and then hydrolyzed by 3-galactosidase (lactase) into glucose and galactose. It is generally accepted that galactose is conveyed to the liver, where it is converted to glucose by the Leloir pathway (18). In the previous studies, enzyme activities belonging to this pathway have been found in the liver (3, 5, 8, 33), kidney (3, 5, 8, 16, 20, 25, 34), intestine (23), brain (21,32,40) and myocardium (21) etc. On the other hand, it has been reported that galactose is an important constituent of the glycoproteins, glycolipids and mucopolysaccharides (1,4,10,13,14,15,22).

Tissue distribution and metabolic fate of 35S from 35S-taurine in pregnant mice by whole-body autoradiographic and biochemical study.

“…After developing and drying, horizontal scratches were made in the silica gel on the plate 3 mm apart, and the radioactivity was measured with an Aloka liquid scintillation counter (6,27). Radioactivity of each peak on the chromatogram was corrected with the original radioactivity (cpm/gram of wet weight) of the acid-soluble fraction of each organ.…”