Kugai N, Koide Y, Kimura S, Yamashita K, Ogata E
Endocrinol Jpn. 1981 Oct;28(5):653-61. doi: 10.1507/endocrj1954.28.653.
In an attempt to study the influence of vitamin D metabolites on PTH secretion, serum calcium and urinary excretion of cAMP were sequentially measured in conscious perfused rats, and the effects of a single iv injection of the metabolites on these parameters were examined. Four hours after the administration of 0.25 microgram/kg (0.6 nmol/kg, probably a physiological dose) of 1 alpha, 25-dihydroxycholecalciferol [1 alpha, 25 (OH)2D3], the urinary excretion of cAMP decreased to a level compatible with that of parathyroidectomized rats (approximately 60% of the initial value; P less than 0.05) and this level was sustained for nearly 24 h. Serum concentrations of calcium (total and ionized) did not change. In parathyroidectomized rats which were continuously infused with bovine PTH (1 U/h), the vitamin D metabolite had no significant effect on the urinary excretion of cAMP. 24 R, 25-dihydroxcholecalciferol (12.5 microgram/kg) had no significant effect either on the urinary excretion of cAMP or on serum calcium. These results suggest that in rats, a physiological dose of 1 alpha, 25(OH)2D3 inhibits PTH secretion without causing a significant rise iu serum calcium, reflecting a feed-back mechanism between active vitamin D metabolite, 1 alpha, 25(OH)2D3 and the parathyroid glands.
为了研究维生素D代谢产物对甲状旁腺激素（PTH）分泌的影响，对清醒的灌注大鼠依次测定血清钙和环磷酸腺苷（cAMP）的尿排泄量，并检测单次静脉注射这些代谢产物对这些参数的影响。给予0.25微克/千克（0.6纳摩尔/千克，可能是生理剂量）的1α，25-二羟胆钙化醇[1α，25（OH）2D3] 4小时后，cAMP的尿排泄量降至与甲状旁腺切除大鼠相当的水平（约为初始值的60%；P<0.05），且该水平维持近24小时。血清钙浓度（总钙和离子钙）未发生变化。在持续输注牛PTH（1单位/小时）的甲状旁腺切除大鼠中，维生素D代谢产物对cAMP的尿排泄量无显著影响。24R，25-二羟胆钙化醇（12.5微克/千克）对cAMP的尿排泄量或血清钙均无显著影响。这些结果表明，在大鼠中，生理剂量的1α，25（OH）2D3抑制PTH分泌，而不会导致血清钙显著升高，这反映了活性维生素D代谢产物1α，25（OH）2D3与甲状旁腺之间的反馈机制。
