N tau-methylhistidine release: contributions of rat skeletal muscle, GI tract, and skin.
The relative contributions of skeletal muscle, gastrointestinal tract, and skin to urinary N tau-methylhistidine (MH) excretion were estimated during in vitro studies using the rat hemicorpus preparation. After 0.5 h of perfusion, MH release into the perfusate was linear for 3 h and averaged 29.8 nmol . h-1 . 100 g hemicorpus-1. In vivo, 24-h urinary MH excretion averaged 37.3 nmol . h-1 . 100 g body wt-1. The ratio of soft tissue to skin weight is equal (3.2:1) in the whole rat and in the hemicorpus. The gastrointestinal tract released 16.0 nmol . h-1 . 100 g body wt-1 or approximately 41% of the total urinary MH excretion. Preparations perfused with or without skin showed modest differences in the rate of MH release that were not statistically significant. Skeletal muscle contains 89.8% of total body MH content, whereas gastrointestinal tract and skin contain 3.8 and 6.4%, respectively. Gastrointestinal tract actomyosin turns over rapidly with a fractional catabolic rate of 24%/day versus 1.4%/day for skeletal muscle actomyosin.
D000818:Animals; D004064:Digestive System / Q000378:metabolism*; D006639:Histidine / Q000031:analogs & derivatives*; D007700:Kinetics; D008297:Male; D008762:Methylhistidines / Q000378:metabolism / Q000652:urine*; D009132:Muscles / Q000378:metabolism*; D009928:Organ Specificity; D010477:Perfusion; D051381:Rats; D011919:Rats, Inbred Strains; D012867:Skin / Q000378:metabolism*
D008762:Methylhistidines; D006639:Histidine; C028118:3-methylhistidine