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Intracellular ADP modulates the Ca2+ release-activated Ca2+ current in a temperature- and Ca2+-dependent Way
B Innocenti1, T Pozzan, C Fasolato
1Department of Biomedical Sciences, CNR Center for the Study of Biomembranes, University of Padova, Via Trieste 75, 35131 Padova, Italy.
The Journal of Biological Chemistry
|April 12, 1996
Summary
Adenosine diphosphate (ADP) inhibits calcium release-activated calcium current (ICRAC) in RBL-1 cells, suggesting nucleotide levels link cell metabolism to calcium influx. This finding impacts understanding of calcium signaling in nonexcitable cells.
Area of Science:
- Cell Biology
- Physiology
- Biochemistry
Background:
- RBL-1 cells exhibit high calcium release-activated calcium current (ICRAC), a key calcium influx pathway in nonexcitable cells.
- Metabolic drugs are known inhibitors of store-operated calcium influx.
Purpose of the Study:
- To investigate the role of intracellular adenine and guanine nucleotide levels as coupling factors between ICRAC and cell metabolism.
- To determine if ADP influences ICRAC in RBL-1 cells.
Main Methods:
- Whole-cell patch-clamp technique to measure ICRAC.
- Application of ADP and other nucleotides to the intracellular solution.
- Manipulation of intracellular calcium buffering capacity and temperature.
Main Results:
- Addition of ADP significantly reduced inositol 1,4,5-trisphosphate-induced ICRAC in RBL-1 cells.
- The inhibitory effect of ADP was temperature-dependent, required low intracellular calcium buffering, and involved a cytosolic factor.
- ADP demonstrated specificity, with partial mimicry by ADPbetaS and AMP, but not GDP or GTP.
Conclusions:
- Intracellular ADP levels can regulate ICRAC, suggesting a metabolic link to calcium influx.
- This regulatory pathway is distinct from other known ICRAC modulation mechanisms.
- The findings provide new insights into the control of calcium signaling in nonexcitable cells.