Wald H, Hayek T, Popovtzer M M
Proc Soc Exp Biol Med. 1985 Nov;180(2):219-23. doi: 10.3181/00379727-180-42167.
The effect of 24,25(OH)2D3 on 1,25(OH)2D3-induced hypercalcemia was studied in normal rats. Serum (S) levels and urinary excretion of Ca2+ (UCaV) were measured in (a) control rats, (b) rats receiving a daily sc injection of 54 ng 1,25(OH)2D3, (c) rats receiving 24,25(OH)2D3 in the same dose and same manner, and (d) rats receiving 1,25(OH)2D3 + 24,25(OH)2D3. The animals were housed in metabolic cages and 24-hr urine specimens were collected. After 24 hr SCa2+ increased similarly with 1,25(OH)2D3 and with 1,25(OH)2D3 + 24,25(OH)2D3, while 24,25(OH)2D3 alone did not change SCa2+. UCaV after 24 hr increased significantly less (P less than 0.025) with 1,25(OH)2D3 + 24,25(OH)2D3 than with 1,25(OH)2D3 alone. After 5 days of 1,25(OH)2D3, SCa2+ rose from 5.1 +/- 0.15 to 6.29 +/- 0.08 whereas 1,25(OH)2D3 + 24,25(OH)2D3 effected a greater increase in SCa2+ up to 6.63 +/- 0.09 (P less than 0.01). 24,25(OH)2D3 alone did not change SCa2+. UCaV after 5 days of treatment rose similarly with 1,25(OH)2D3 and with 1,25(OH)2D3 + 24,25(OH)2D3. After 10 days of 1,25(OH)2D3 SCa2+ was 6.17 +/- 0.15 meq/liter while with the combination SCa2+ rose to 6.74 +/- 0.2 (P less than 0.025). 24,25(OH)2D3 alone did not change SCa2+. These results show that (a) 24,25(OH)2D3 alone does not alter SCa2+ in normal rats, (b) combined administration of 1,25(OH)2D3 + 24,25(OH)2D3 enhances the hypercalcemic response to 1,25(OH)2D3 without a parallel increase in UCaV, and (c) it is suggested that the effect of 24,25(OH)2D3 on serum Ca2+ level, at least partly, may result from its hypocalciuric effect.
在正常大鼠中研究了24,25(OH)₂D₃对1,25(OH)₂D₃诱导的高钙血症的影响。测定了以下几组大鼠的血清（S）钙水平和尿钙（UCaV）排泄量：（a）对照大鼠；（b）每天皮下注射54 ng 1,25(OH)₂D₃的大鼠；（c）以相同剂量和方式接受24,25(OH)₂D₃的大鼠；（d）接受1,25(OH)₂D₃ + 24,25(OH)₂D₃的大鼠。将动物饲养在代谢笼中并收集24小时尿液标本。24小时后，1,25(OH)₂D₃组和1,25(OH)₂D₃ + 24,25(OH)₂D₃组的血清总钙（SCa₂⁺）升高情况相似，而单独使用24,25(OH)₂D₃组的SCa₂⁺未改变。24小时后，1,25(OH)₂D₃ + 24,25(OH)₂D₃组的UCaV升高幅度明显小于（P < 0.025）单独使用1,25(OH)₂D₃组。1,25(OH)₂D₃注射5天后，SCa₂⁺从5.1±0.15升至6.29±0.08，而1,25(OH)₂D₃ + 24,25(OH)₂D₃组的SCa₂⁺升高幅度更大，达到6.63±0.09（P < 0.01）。单独使用24,25(OH)₂D₃组的SCa₂⁺未改变。治疗5天后，1,25(OH)₂D₃组和1,25(OH)₂D₃ + 24,25(OH)₂D₃组的UCaV升高情况相似。1,25(OH)₂D₃注射10天后，SCa₂⁺为6.17±0.15 mEq/升，而联合用药组SCa₂⁺升至6.74±0.2（P < 0.025）。单独使用24,25(OH)₂D₃组的SCa₂⁺未改变。这些结果表明：（a）单独使用24,25(OH)₂D₃不会改变正常大鼠的SCa₂⁺；（b）联合给予1,25(OH)₂D₃ + 24,25(OH)₂D₃可增强对1,25(OH)₂D₃的高钙血症反应，且UCaV没有相应增加；（c）提示24,25(OH)₂D₃对血清钙水平的影响至少部分可能源于其降低尿钙的作用。
