| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1988: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1987: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
We previously reported that the concentration of plasma fibronection (pFN) is increased in patients with hyperthyroidism and decreased in those eith hypothroidism. In this work, labeled pFN was given intravenously to euthyroid, hyperthyroid, and hypothyroid rabbits to examine its metabolism in states of thyroid dysfunction.
In euthyroid rabbits, the serum concentration of thyroxine (T4) was 2.94 0.59 g/dl, and that of pFN was 24.2 1.2 mg/dl. with ^<125>I-FN as tracer, the half life was estimated as 72.8 2.6 hours, the fractional catabolic rate (FCR) as 2.08 0.07 %/h, the rate of synthesis (SR) as.3.8 0.20 mg/kg/day and j1/j2 (the ratio of the exzchange coefficients between intravascular and extravascular compartments) of pFN as 0.295 0.051. In hyperthyroid rabbits, obtained by treatment with 1-thyroxine, the serum T4 concentration was increased to 5.73 1.58 g/dl and the pFN concentration to 29.6 2.2 mg/dl. In these animals, the half life of pFN was shortened to 59.8 1.0 hours, the FCR was slightly increased to 3.07 0.52 %/h and the SR was greatly increased to 7.13 1.17 mg/kg/day In hypothyroid rabbits, obtained by treatment with methyltiouracil, the serum T4 and pFN levels were reduced to 1.50 0.36 g/dl and to 20.7 1.7 mg.dl, respectively. The values of j1/j2 did not significantly change during this work.
These results indicate that (1) changes in serum T4 concentrations directly correlate with the SR of pFN, (2) increase in the pFN concentration in hyperthyroid rabbits can be explained by greater increase in the SR than shortening of the half life of pFN, and (3) decrease in the pFN concentration in hypothroid rabbits occures by greater decrease in the SR than in prolongation of the half life of pFN.
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