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Parathyroid gland calcium receptor mRNA levels are unaffected by chronic renal insufficiency or low dietary calcium in rats
- Source :
- Endocrine. 3:769-774
- Publication Year :
- 1995
- Publisher :
- Springer Science and Business Media LLC, 1995.
-
Abstract
- Extracellular ionized calcium (Ca(2+)) is the primary physiological regulator of parathyroid hormone (PTH) secretion and the G protein-coupled receptor (CaR) that mediates this response has been cloned from bovine and human parathyroid glands. The Ca(2+) set-point for the regulation of PTH secretion is right-shifted in primary hyperparathyroidism (1°HPT), but whether there is a similar shift in 2°HPT is unclear. Additionally, the molecular defects associated with such changes in the set-point remain uncharacterized. These experiments were designed to determine (1) if changes in set-point occur in rats with 2°HPT induced by chronic renal insufficiency (CRI) or dietary Ca deficiency, and (2) whether any changes in set-point are mirrored by changes in steady-state mRNA levels for the parathyroid CaR. CaR mRNA levels were quantified in pairs of glands from individual rats using a solution hybridization assay. Blood urea nitrogen and PTH levels were ∼ 4-fold higher in rats with CRI induced by 5/6 nephrectomy 7 weeks earlier. Rats with CRI were also significantly hypocalcemic and hyperphosphatemic. The setpoint was unchanged in CRI rats and CaR mRNA levels were also unaffected. Normal rats fed a 0.02% Ca diet for 6 weeks were markedly hypocalcemic, and had 10- and 15-fold increases in plasma PTH and 1,25-dihydroxyvitamin D(3) levels, respectively. Technical problems prevented assessment of the set-point in these animals, but parathyroid gland CaR mRNA levels were identical in both dietary groups. Thus, neither alterations in mRNA levels for the CaR nor changes in the set-point play demonstrable roles in the pathogenesis of 2°HPT in these models.
- Subjects :
- Calcium metabolism
medicine.medical_specialty
Endocrinology, Diabetes and Metabolism
chemistry.chemical_element
Parathyroid hormone
Calcium
medicine.disease
Endocrinology
medicine.anatomical_structure
chemistry
Internal medicine
medicine
Solution hybridization
Parathyroid gland
Secondary hyperparathyroidism
Calcium-sensing receptor
Primary hyperparathyroidism
Subjects
Details
- ISSN :
- 15590100 and 0969711X
- Volume :
- 3
- Database :
- OpenAIRE
- Journal :
- Endocrine
- Accession number :
- edsair.doi.dedup.....b102b2f5f14860726b458d9436260491
- Full Text :
- https://doi.org/10.1007/bf02935679