The calcium-sensing receptor is required for normal calcium homeostasis independent of parathyroid hormone
J. Clin. Invest. Claudine H. Kos, et al. 111:1021 doi:10.1172/JCI17416 [Go to this article.]

Figure 5
Expression levels of CaT1 and CaT2/ECaC are altered in Pth–/–CaR–/– mice relative to control littermates. The mRNA expression levels of CaT1 (black bars) and CaT2/ECaC (white bars) in the duodenum and kidney were assessed by real-time quantitative PCR and normalized against GAPDH mRNA levels. We compared expression in RNA samples from three pairs of sex-matched littermates maintained on high-calcium diets (2% calcium, top) and three pairs of sex-matched littermates on regular diets (0.81% calcium, bottom). We performed assays in duplicate for each RNA sample. Renal CaT1 and CaT2/ECaC expression were consistently higher in CaR-deficient mice, regardless of diet (mean increased expression of 65% and 60%, respectively). These differences reached statistical significance with P = 0.015 and P = 0.0025, respectively, in paired t tests. Intestinal CaT1 expression was highly variable. In animals fed high-calcium diets as well as those fed regular diets, the overall trend was toward increased CaT1 expression in the CaR-deficient animals, but this trend did not reach statistical significance either when the groups were analyzed separately according to diet or when all six pairs were analyzed together.