Schröder B, Kaune R, Schlumbohm C, Breves G, Harmeyer J
Department of Veterinary-Physiology, Justus-Liebig-University, Giessen, Germany.
Calcif Tissue Int. 1993 Apr;52(4):305-9. doi: 10.1007/BF00296656.
The role of 1,25-dihydroxycholecalciferol (calcitriol) for intestinal calcium (Ca2+) absorption was studied in newborn (< 1 week old) and weaned piglets (> 6 weeks old). In both groups, normal piglets and piglets suffering from inherited pseudo vitamin D-deficiency rickets, type I (PVDRI) were used. In this inherited disorder, renal production of calcitriol is absent. Plasma samples were assayed for calcitriol and total Ca, and dissociation constants (Kd) and maximum binding capacities (Bmax) of intestinal calcitriol receptors were determined under equilibrium conditions at 4 degrees C. Unidirectional Ca(2+)-flux rates were measured across stripped duodenal mucosae in Ussing chambers in the absence of electrochemical gradients. The plasma calcitriol concentrations of neonatal (26.5 +/- 7.1 pg/ml, n = 11; mean +/- SEM) and weaned PVDRI piglets (18.8 +/- 5.7 pg/ml, n = 8) were unphysiologically low and differed significantly from control animals (83.6 +/- 14.8 pg/ml, n = 8, and 86.9 +/- 9.6 pg/ml, n = 11, respectively). However, newborn PVDRI piglets had normal plasma Ca levels at least during the first days of life. They became hypocalcemic and developed clinical symptoms of rickets during the following weeks. In newborn PVDRI and control piglets, Bmax was significantly lower (84 +/- 28 fmol/mg protein and 127 +/- 55 fmol/mg protein, n = 9, respectively) than in weaned piglets (741 +/- 82 fmol/mg protein, n = 9, and 778 +/- 121 fmol/mg protein, n = 8, respectively). Significant net Ca(2+)-fluxes were found in both newborn PVDRI and control piglets (88.8 +/- 25.1 nmol.cm-2 x h-1, n = 6, and 86.5 +/- 10.5 nmol.cm-2 x h-1, n = 9, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
研究了1,25 - 二羟胆钙化醇（骨化三醇）对新生仔猪（小于1周龄）和断奶仔猪（大于6周龄）肠道钙（Ca2+）吸收的作用。在这两组中，均使用了正常仔猪和患有I型遗传性假性维生素D缺乏性佝偻病（PVDRI）的仔猪。在这种遗传性疾病中，肾脏不产生骨化三醇。测定血浆样本中的骨化三醇和总钙，并在4℃平衡条件下测定肠道骨化三醇受体的解离常数（Kd）和最大结合容量（Bmax）。在没有电化学梯度的情况下，在Ussing小室中测量穿过剥离十二指肠黏膜的单向Ca(2+)通量率。新生PVDRI仔猪（26.5±7.1 pg/ml，n = 11；平均值±标准误）和断奶PVDRI仔猪（18.8±5.7 pg/ml，n = 8）的血浆骨化三醇浓度低于生理水平，且与对照动物（分别为83.6±14.8 pg/ml，n = 8和86.9±9.6 pg/ml，n = 11）有显著差异。然而，新生PVDRI仔猪至少在出生后的头几天血浆钙水平正常。在接下来的几周内，它们出现低钙血症并出现佝偻病的临床症状。在新生PVDRI仔猪和对照仔猪中，Bmax显著低于断奶仔猪（分别为84±28 fmol/mg蛋白和127±55 fmol/mg蛋白，n = 9；以及741±82 fmol/mg蛋白，n = 9和778±121 fmol/mg蛋白，n = 8）。在新生PVDRI仔猪和对照仔猪中均发现了显著的净Ca(2+)通量（分别为88.8±25.1 nmol·cm-2·h-1，n = 6和86.5±10.5 nmol·cm-2·h-1，n = 9）。（摘要截断于250字）
