Hennessen U, Drüeke T, Comte L, Steuf M C, McCarron D A, Lacour B
INSERM U90, Hôpital Necker, Paris, France.
Biochem Biophys Res Commun. 1990 Jul 31;170(2):742-7. doi: 10.1016/0006-291x(90)92153-q.
Arterial hypertension in the spontaneously hypertensive rat (SHR) is associated with an abnormal Ca2+ homeostasis, compared with its normotensive control, the Wistar Kyoto rat (WKY). In particular, epithelial Ca2+ transport is perturbed, with intestinal absorption and renal tubular reabsorption being decreased in the adolescent and adult SHR. In the present study we examined Ca2+ uptake into isolated duodenal brush-border membrane vesicles (BBMV) in 12-14 week-old male rats. This uptake can be separated in a nonsaturable and a saturable component. The latter follows Michaelis-Menten kinetics. Vmax of this component was found to be significantly higher (p less than 0.05) in SHR than in WKY (0.58 +/- 0.19 versus 0.35 +/- 0.06 nmol/mg protein x 10 sec, mean +/- SD) whereas Km did not differ. Thus, the defect in the intestinal Ca2+ absorption previously identified in the SHR of this age is not due to a decrease in Ca uptake at the level of the duodenal brush-border membrane, but is most likely located in the baso-lateral membrane.
与正常血压对照的Wistar Kyoto大鼠（WKY）相比，自发性高血压大鼠（SHR）的动脉高血压与异常的Ca2+稳态有关。特别是，上皮细胞Ca2+转运受到干扰，青春期和成年SHR的肠道吸收和肾小管重吸收均降低。在本研究中，我们检测了12 - 14周龄雄性大鼠分离的十二指肠刷状缘膜囊泡（BBMV）对Ca2+的摄取。这种摄取可分为非饱和成分和饱和成分。后者遵循米氏动力学。发现该成分的Vmax在SHR中显著高于WKY（p小于0.05）（分别为0.58±0.19与0.35±0.06 nmol/mg蛋白质×10秒，均值±标准差），而Km没有差异。因此，先前在该年龄的SHR中发现的肠道Ca2+吸收缺陷并非由于十二指肠刷状缘膜水平的Ca摄取减少，而最有可能位于基底外侧膜。
