Loading...
Please wait, while we are loading the content...
Similar Documents
Re-modeling Chara action potential: I. from Thiel model of $Ca^{2+}$transient to action potential form
| Content Provider | Directory of Open Access Journals (DOAJ) |
|---|---|
| Author | Sabah Al Khazaaly Mary Jane Beilby |
| Abstract | Thiel and colleagues demonstrated that the all-or-none nature of Chara action potential(AP) is determined by formation of a second messenger, probably inositol triphosphate $(IP_{3}$), whichin turn releases $Ca^{2+}$ from internal stores. The $Ca^{2+}$-activated $Cl^{–}$ channels are the main agent of thedepolarization phase of the AP. Once the $Ca^{2+}$ is re-sequestered by the calcium pumps, the chlorideconductance drops and depolarization-activated outward rectifier current, the background current andthe proton pump current return the membrane potential difference (PD) to resting level. Departingfrom the Thiel model of transient increase of $Ca^{2+}$ concentration, we set up membrane PD rate ofchange equation to calculate the AP form by numerical integration. Compared to data, this model APdepolarized more gradually. We introduced a prompt $Ca^{2+}$ transient from the outside, achieving agood correspondence with the experimental AP. In Chara cells subjected to 50 mM NaCl/0.1 $mMCa^{2+}$ medium, the AP duration increased from 2 s to up to 50 s and the APs were often spontaneous.The lack of stimulating pulse revealed a sharp positive spike at the beginning of each AP, confirmingthat Chara plasma membrane may contain transient receptor potential (TRP)-like channels, possiblyactivated by another second messenger diacylglycerol (DAG) formed at the same time as $IP_{3}$. Thelong duration of the saline AP can be modeled by decreasing the coefficients in the Hill equationdescribing the $Ca^{2+}$ pumps on the internal stores. The model provides new insights into the characeanAP and suggests a range of experiments. |
| Related Links | http://www.aimspress.com/biophysics/article/988/fulltext.html |
| ISSN | 23779098 |
| DOI | 10.3934/biophy.2016.3.431 |
| Journal | AIMS Biophysics |
| Issue Number | 3 |
| Volume Number | 3 |
| Language | English |
| Publisher | AIMS Press |
| Publisher Date | 2016-01-01 |
| Publisher Place | United States |
| Access Restriction | Open |
| Subject Keyword | Biology (general) Biotechnology Action Potential Chara Cytoplasmic $ca^{2+}$ Concentration $ca^{2+}$ Channels On Internal Stores Inositol Triphosphate $ca^{2+}$-activated $cl^{–}$ Channels Trp Channels $ca^{2+}$ Pump Biology (General) Technology |
| Content Type | Text |
| Resource Type | Article |
| Subject | Structural Biology Molecular Biology Biochemistry Biophysics |
