Please wait, while we are loading the content...
Please wait, while we are loading the content...
| Content Provider | PubMed Central |
|---|---|
| Author | Ho, W. K. Earm, Y. E. Lee, S. H. Brown, H. F. Noble, D. |
| Abstract | 1. The properties of the delayed rectifier K+ current (IK) of rabbit isolated sino-atrial node cells were investigated in high (140 mM) [K+]o using the whole-cell-clamp technique. 2. Hyperpolarizing clamp pulses from 0 mV induced an instantaneous current jump (I-V relation linear) followed by a time-dependent increase in inward current to a peak, whereas depolarizing clamp pulses induced little outward current. The peak I-V relation showed a strong inward rectification. The inwardly rectifying current was blocked by E-4031. 3. The inward K+ current induced by hyperpolarizing clamp pulses from 0 mV relaxed after reaching its peak. The rate of the relaxation increased as the membrane potential became more negative and concentrations of external Ca2+ or Mg2+ were increased. The steady-state current was smaller as the relaxation of the current accelerated on increasing [Ca2+]o or [Mg2+]o. 4. Depolarizing clamp pulses from -80 mV induced an increase in inward current, reaching a steady state. The amplitude of the steady-state current became smaller and the rate of current increase became slower as [Ca2+]o or [Mg2+]o was increased. 5. The effects of Ca2+ and Mg2+ are well explained by a time- and voltage-dependent blockade of the K+ channel by these ions. The fractional electrical distance of the binding site calculated from the voltage dependence of the blocking rate constant is 0.69 for Ca2+ and 0.88 for Mg2+. The blocking rate constant at 0 mV for Ca2+ is about 15 times faster than that for Mg2+, indicating stronger effects of Ca2+. 6. A re-interpretation of IK in sino-atrial node cells is proposed: there are two independent gates (an activation gate which opens on hyperpolarization and an inactivation gate which closes on hyperpolarization) and a binding site for Ca2+ and Mg2+ inside the channel. Binding of these ions, which is facilitated by hyperpolarization, causes channel blockade, resulting in the observed voltage dependence of IK in physiological concentrations of Ca2+ and Mg2+. |
| Starting Page | 727 |
| File Format | |
| ISSN | 14697793 |
| e-ISSN | 14697793 |
| Journal | The Journal of Physiology |
| Issue Number | Pt 3 |
| Volume Number | 494 |
| Language | English |
| Publisher Date | 1996-08-01 |
| Access Restriction | Open |
| Subject Keyword | Research in Higher Education |
| Content Type | Text |
| Resource Type | Article |
| Subject | Physiology Sports Science |
National Digital Library of India (NDLI) is a virtual repository of learning resources which is not just a repository with search/browse facilities but provides a host of services for the learner community. It is sponsored and mentored by Ministry of Education, Government of India, through its National Mission on Education through Information and Communication Technology (NMEICT). Filtered and federated searching is employed to facilitate focused searching so that learners can find the right resource with least effort and in minimum time. NDLI provides user group-specific services such as Examination Preparatory for School and College students and job aspirants. Services for Researchers and general learners are also provided. NDLI is designed to hold content of any language and provides interface support for 10 most widely used Indian languages. It is built to provide support for all academic levels including researchers and life-long learners, all disciplines, all popular forms of access devices and differently-abled learners. It is designed to enable people to learn and prepare from best practices from all over the world and to facilitate researchers to perform inter-linked exploration from multiple sources. It is developed, operated and maintained from Indian Institute of Technology Kharagpur.
Learn more about this project from here.
NDLI is a conglomeration of freely available or institutionally contributed or donated or publisher managed contents. Almost all these contents are hosted and accessed from respective sources. The responsibility for authenticity, relevance, completeness, accuracy, reliability and suitability of these contents rests with the respective organization and NDLI has no responsibility or liability for these. Every effort is made to keep the NDLI portal up and running smoothly unless there are some unavoidable technical issues.
Ministry of Education, through its National Mission on Education through Information and Communication Technology (NMEICT), has sponsored and funded the National Digital Library of India (NDLI) project.
| Sl. | Authority | Responsibilities | Communication Details |
|---|---|---|---|
| 1 | Ministry of Education (GoI), Department of Higher Education |
Sanctioning Authority | https://www.education.gov.in/ict-initiatives |
| 2 | Indian Institute of Technology Kharagpur | Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project | https://www.iitkgp.ac.in |
| 3 | National Digital Library of India Office, Indian Institute of Technology Kharagpur | The administrative and infrastructural headquarters of the project | Dr. B. Sutradhar bsutra@ndl.gov.in |
| 4 | Project PI / Joint PI | Principal Investigator and Joint Principal Investigators of the project |
Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon |
| 5 | Website/Portal (Helpdesk) | Queries regarding NDLI and its services | support@ndl.gov.in |
| 6 | Contents and Copyright Issues | Queries related to content curation and copyright issues | content@ndl.gov.in |
| 7 | National Digital Library of India Club (NDLI Club) | Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach | clubsupport@ndl.gov.in |
| 8 | Digital Preservation Centre (DPC) | Assistance with digitizing and archiving copyright-free printed books | dpc@ndl.gov.in |
| 9 | IDR Setup or Support | Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops | idr@ndl.gov.in |
|
Loading...
|