Loading...
Please wait, while we are loading the content...
Similar Documents
Effect of Monovalent Cations on Na+/Ca2+Exchange and ATP-Dependent Ca2+Transport in Synaptic Plasma Membranes
| Content Provider | Scilit |
|---|---|
| Author | Coutinho, O. P. Carvalho, A. P. Carvalho, C. A. M. |
| Copyright Year | 1983 |
| Description | Journal: Journal of Neurochemistry Two Ca2+ transport systems were investigated in plasma membrane vesicles isolated from sheep brain cortex synaptosomes by hypotonic lysis and partial purification. Synaptic plasma membrane vesicles loaded with Na+ (Na+i) accumulate Ca2+ in exchange for Na+, provided that a Na+ gradient (in2192out) is present. Agents that dissipate the Na+ gradient (monensin) prevent the Na+/Ca2+ exchange completely. Ca2+ accumulated by Na+/Ca2+ exchange can be released by A 23187, indicating that Ca2+ is accumulated intravesicularly. In the absence of any Na+ gradient (K+i-loaded vesicles), the membrane vesicles also accumulate Ca2+ owing to ATP hydrolysis. Monovalent cations stimulate Na+/Ca2+ exchange as well as the ATP-dependent Ca2+ uptake activity. Taking the value for Na+/Ca2+ exchange in the presence of choline chloride (external cation) as reference, other monovalent cations in the external media have the following effects: K+ or NH4+ stimulates Na+/Ca2+ exchange; Li+ or Cs+ inhibits Na+/Ca2+ exchange. The ATP-dependent Ca2+ transport system is stimulated by increasing K+ concentrations in the external medium (Km for K+ is 15 mM). Replacing K+ by Na+ in the external medium inhibits the ATP-dependent Ca2+ uptake, and this effect is due more to the reduction of K+ than to the elevation of Na+. The results suggest that synaptic membrane vesicles isolated from sheep brain cortex synaptosomes possess mechanisms for Na+/Ca2+ exchange and ATP-dependent Ca2+ uptake, whose activity may be regulated by monovalent cations, specifically K+, at physiological concentrations.http://dx.doi.org/10.1111/j.1471-4159.1983.tb04793. |
| Related Links | https://core.ac.uk/download/pdf/144013145.pdf http://onlinelibrary.wiley.com/doi/10.1111/j.1471-4159.1983.tb04793.x/pdf |
| Ending Page | 676 |
| Page Count | 7 |
| Starting Page | 670 |
| e-ISSN | 14714159 |
| DOI | 10.1111/j.1471-4159.1983.tb04793.x |
| Journal | Journal of Neurochemistry |
| Issue Number | 3 |
| Volume Number | 41 |
| Language | English |
| Publisher | Wiley-Blackwell |
| Publisher Date | 1983-09-01 |
| Access Restriction | Open |
| Subject Keyword | Journal: Journal of Neurochemistry Synaptic Membranes Na+/ca2+ Exchange Atp‐dependent Ca2+ Transport Monovalent Cations |
| Content Type | Text |
| Resource Type | Article |
