Related Experiment Videos
Cloned and expressed rat Ca2+-sensing receptor
M Ruat1, A M Snowman, L D Hester
1Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
The Journal of Biological Chemistry
|March 15, 1996
Summary
The rat brain calcium-sensing receptor (CaSR) in CHO cells shows cooperative responses to calcium (Ca2+). Magnesium (Mg2+) acts as a partial agonist, influencing CaSR activity at clinically relevant serum concentrations.
Area of Science:
- Biochemistry
- Cell Biology
- Pharmacology
Background:
- The calcium-sensing receptor (CaSR) plays a crucial role in regulating calcium homeostasis.
- Understanding CaSR's response to divalent cations is vital for physiological and pathological conditions.
Purpose of the Study:
- To characterize the functional expression of the rat brain Ca2+ sensing receptor (CaSR) in a heterologous system.
- To investigate the dose-response characteristics of Ca2+ and Mg2+ on CaSR-mediated signaling pathways.
Main Methods:
- Stable expression of rat brain CaSR cDNA in Chinese hamster ovary (CHO) cells.
- Measurement of phosphatidylinositol hydrolysis and arachidonic acid (AA) release in response to varying Ca2+ and Mg2+ concentrations.
Main Results:
- Ca2+ elicited cooperative responses (Hill coefficients of 4-5) for both phosphatidylinositol hydrolysis and AA release, with a threshold of 1.5 mM Ca2+.
- Mg2+ acted as a partial agonist, producing approximately 50% of the maximal response observed with Ca2+.
- Mg2+ augmented Ca2+-stimulated responses, indicating its influence at physiological concentrations.
Conclusions:
- The CaSR exhibits complex, cooperative activation by Ca2+.
- Mg2+ significantly modulates CaSR activity, suggesting its clinical relevance in conditions affecting serum divalent cation levels.
- This study provides insights into the intricate regulation of CaSR by extracellular divalent cations.