Hennessen U, Comte L, Steuf M C, Lacour B, Drüeke T, McCarron D A
Inserm Unité 90, Départment de Néphrologie, Hôpital Necker, Paris, France.
Contrib Nephrol. 1991;90:42-8. doi: 10.1159/000420121.
Arterial hypertension in the SHR is associated with disturbances of calcium homeostasis, compared with its normotensive control, the WKY. In order to study intestinal Ca2+ handling at the subcellular level, we examined 45Ca2+ uptake kinetics in isolated brush-border membrane vesicles (BBMV). Experiments were conducted in male, 12- to 14-week-old rats on a 1% Ca diet. BBMV were purified by the method of Forstner et al. No difference in BBMV enrichment was observed between SHR and WKY. Ca2+ uptake was studied at various Ca2+ concentrations in the incubation medium (0.025-1.0 mM) and could be separated into a nonsaturable and a saturable component. The saturable component followed Michaelis-Menten kinetics. Vmax in the SHR was greater than in the WKY: 0.576 +/- 0.186 (n = 6) vs. 0.346 +/- 0.10 nmol/mg protein x 10 s (n = 6), mean +/- SD, p less than 0.05. However, Km was not different in the two animal strains. In conclusion, mediated Ca2+ transport into duodenal BBMV was increased in the adolescent SHR. When considering that the transcellular duodenal Ca2+ flux is decreased in the SHR at this age, the rate-limiting step of perturbed transeptithelial Ca2+ transport is probably localized at the site of the basolateral membrane.
与正常血压对照品系WKY相比，SHR中的动脉高血压与钙稳态紊乱有关。为了在亚细胞水平研究肠道Ca2+处理，我们检测了分离的刷状缘膜囊泡（BBMV）中45Ca2+的摄取动力学。实验在12至14周龄、食用1%钙饮食的雄性大鼠中进行。BBMV通过Forstner等人的方法纯化。在SHR和WKY之间未观察到BBMV富集的差异。在孵育培养基中不同Ca2+浓度（0.025 - 1.0 mM）下研究Ca2+摄取，其可分为非饱和成分和饱和成分。饱和成分遵循米氏动力学。SHR中的Vmax大于WKY：0.576 +/- 0.186（n = 6）对0.346 +/- 0.10 nmol/mg蛋白质x 10秒（n = 6），平均值 +/- 标准差，p小于0.05。然而，两种动物品系中的Km没有差异。总之，青春期SHR中介导的Ca2+转运至十二指肠BBMV增加。考虑到这个年龄段SHR中十二指肠跨细胞Ca2+通量降低，跨上皮Ca2+转运受干扰的限速步骤可能位于基底外侧膜部位。
