Summary
This study was undertaken to elucidate the effect of glibenclamide, one of sulfonylurea drugs, on thyroid hormone metabolism in vivo and on the conversion of thyroxine (T4) to 3,5,3′-triiodothyronine (T3) in the isolated perfused rat liver and kidney. Glibenclamide (0.2 mg/kg body weight) was intraperitoneally administered to normal and streptozotocin-induced (50 mg/kg) diabetic rats for 14 days. The liver and kidney of normal rats were perfused for 30 minutes with a synthetic medium containing 20 μg/dl T4 and glibenclamide (200 or 400 ng/ml), and production of T3 in the tissues was measured by radioimmunoassay.
Serum T4 and T3 levels in control and streptozotocin-induced diabetic rats were not changed by daily intraperitoneal glibenclamide administration.
The production of T3 (111 ± 40 and 95 ± 16 ng/g/30 min, mean ± SD) and the conversion rate of T4 to T3 (11.1 ± 2.9 and 10.2 ± 2.3%) in the liver perfused with glibenclamide (200 and 400 ng/ml) were not significantly different from those in controls (109 ± 41 ng/g/30 min and 12.8 ± 5.4%). And those (120 ± 33 and 99 ± 19 ng/g/30 min, and 3.5 ± 0.6 and 2.5 ± 0.4%) in the kidney perfused with glibenclamide (200 and 400 ng/ml) were similar to those in controls (98 % 33 ng/g/30 min and 3.0 ± 1.5%).
These results suggest that glibenclamide had no effect on thyroid hormdne metabolism in vivo and in vitro in rats.
Key-Words
Serum T
4
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Serum T
3
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Conversion of T
4 to T
3
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Perfused Rat Liver
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Perfused Rat Kidney
