A study of iodothyronine 5'-monodeiodinase activities in normal and pathological tissues in man and their comparison with activities in rat tissues.
The present study was undertaken to investigate the peripheral iodothyronine 5'-monodeiodination in different human and rat tissues. We studied iodothyronine 5'-monodeiodinase type I (5'-DI) activity in liver, kidney, intestine, right cardiac atrium and skeletal muscle and we compared the results with those in rat tissues. Lodothyronine 5'- monodeiodinase type II (5'-DII) activity was studied in normal and ischemic human heart and in rat normal myocardium and brain. The 5'-DI activity (fmol/min x mg protein) in liver and kidney was significantly higher (p < 0.001, ANOVA) in normal rat tissue than in human. However, no significant differences were observed in 5'-DI activity between normal and tumoral human intestine or between intestinal tissue of man and rat. 5'-DI activity in normal human skeletal muscle was significantly higher than that in rat skeletal muscle (p < 0.05). The 5'-DI activity was lower in human ischemic myocardium when compared to normal myocardium either in humans (p < 0.05) or rat (p < 0.001). The Km of 5'-DI was significantly lower in rat than in human kidney and liver (p < 0.05). We conclude that 1) 5'-DI is distributed widely among extrathyroidal human and rat tissues and 5'-DII activity is detectable both in human and rat heart; 2) 5'-DI activity in liver and kidney is lower in man than in rat; 3) 5'-DI activity in the skeletal muscle is higher in man than in the rat; 4) 5'-DI activity is decreased in tumoral tissues of human liver and kidney and in ischemic myocardium, while no significant difference was found between human and rat cardiac 5'-DII activity.
Sabatino
L
L
Unità di Neuroendocrinologia Cardiovascolare, Istituto di Fisiologia Clinica CNR, Pisa, Italy. lauretta@ifc.pi.cnr.it
Iervasi
G
G
Ferrazzi
P
P
Francesconi
D
D
Chopra
I J
IJ
D000368:Aged; D000818:Animals; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007422:Intestines / Q000201:enzymology*; D007453:Iodide Peroxidase / Q000378:metabolism*; D007668:Kidney / Q000201:enzymology*; D008099:Liver / Q000201:enzymology*; D008297:Male; D018482:Muscle, Skeletal / Q000201:enzymology*; D017202:Myocardial Ischemia / Q000097:blood / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology*; D009369:Neoplasms / Q000097:blood / Q000201:enzymology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013045:Species Specificity; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D000097564:Iodothyronine Deiodinase Type II
D006854:Hydrocortisone; D007453:Iodide Peroxidase; D013974:Thyroxine; D014284:Triiodothyronine; D000097564:Iodothyronine Deiodinase Type II; C109812:iodothyronine deiodinase type I