Please wait, while we are loading the content...
Please wait, while we are loading the content...
| Content Provider | PubMed Central |
|---|---|
| Author | Sasaki, T. Gallacher, D. V. |
| Abstract | 1. ATP activates calcium (Ca2+) influx in mouse lacrimal acinar cells in the absence of phosphoinositide hydrolysis. Extracellular ATP (1 mM) activates receptor-operated cation channels, promoting entry of Na+ and Ca2+ (inward current). This Ca2+ influx in turn activates K+ channels resulting in a delayed, outward, current component. The present study uses patch-clamp current recording techniques to investigate the role of beta-adrenoceptor mechanisms, intracellular cyclic AMP and GTP in the regulation of the ATP-induced inward currents. 2. The beta-adrenoceptor agonist, isoprenaline (1 microM), does not increase the resting membrane currents but markedly enhances the ATP-induced inward and outward currents. This effect of isoprenaline is blocked by the beta-adrenoceptor antagonist propranolol. 3. Internal application of cyclic AMP mimics the potentiating effect of isoprenaline. 100 microM-cyclic AMP increases the ATP-induced inward and outward currents to about 200% as compared to control responses. 4. Pre-treatment of the cells with the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX; 1 mM), also results in a marked potentiation of the ATP-induced inward currents to 170% as compared to control responses. 5. The ATP-induced inward current responses are not blocked by either the removal of extracellular Ca2+ or by chelation of intracellular Ca2+ (by inclusion of 10 mM-EGTA in the recording pipette). Both protocols did however block the potentiating effect of internal cyclic AMP on the ATP-induced inward current responses. 6. Intracellular ATP (10 mM) reduces the amplitude of the inward currents evoked by external ATP application by about 60% and the currents were no longer potentiated by internal cyclic AMP. 7. Intracellular GTP or GTP-gamma-S (100 microM in the pipette solution) potentiates the current responses to ATP, increasing both the amplitude and duration of the inward currents. 8. In excised inside-out patches, with ATP in the recording pipette (i.e. external ATP), the catalytic subunit of the cyclic AMP-dependent protein kinase activated the cation channels. The effect of the catalytic subunit was readily reversible and abolished by an inhibitor of the protein kinase. 9. External ATP activates Ca2+ influx in lacrimal acinar cells by a mechanism that is distinct from that activated by phosphoinositide-coupled receptors. The effect is mediated by direct activation of cation channels in the cell surface membrane which allow for significant entry of Ca2+.(ABSTRACT TRUNCATED AT 400 WORDS) |
| Ending Page | 118 |
| Starting Page | 103 |
| File Format | |
| ISSN | 14697793 |
| e-ISSN | 14697793 |
| Journal | The Journal of Physiology |
| Volume Number | 447 |
| Language | English |
| Publisher Date | 1992-02-01 |
| 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...
|