Caride A J, Chini E N, Homma S, Dousa T P, Penniston J T
Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minn 55905, USA. Caride@Mayo-edu
Kidney Blood Press Res. 1998;21(5):305-9. doi: 10.1159/000025886.
We investigated the localization of mRNA encoding the calcium-sensing receptor (CaSR) along the rat nephron. For this purpose, we combined microdissection of nephron segments and RT-PCR techniques. The results indicate that mRNA encoding rat CaSR is present in rat glomeruli and distal segments (medullary thick ascending limb, cortical thick ascending limb, distal convoluted tubule and cortical collecting duct), whereas it was not detected in proximal convoluted tubules or proximal straight tubules. We also studied whether the CaSR transcription in kidney cortex was modified in response to low dietary phosphate. No significant changes were detected. Given the fact that a low-phosphate diet increased Ca2+ excretion by more than 50-fold, the results suggest that if the CaSR regulates Ca2+ reabsorption, it does so through receptor occupancy by Ca2+ rather than by changes in receptor expression.
我们研究了编码钙敏感受体（CaSR）的mRNA在大鼠肾单位中的定位。为此，我们将肾单位节段的显微切割技术与逆转录聚合酶链反应（RT-PCR）技术相结合。结果表明，编码大鼠CaSR的mRNA存在于大鼠肾小球和远端节段（髓质厚升支、皮质厚升支、远曲小管和皮质集合管），而在近曲小管或近端直小管中未检测到。我们还研究了低磷饮食是否会改变肾皮质中CaSR的转录。未检测到显著变化。鉴于低磷饮食使钙排泄增加了50倍以上，结果表明，如果CaSR调节钙重吸收，其作用方式是通过钙离子占据受体，而非通过受体表达的变化。
