Please wait, while we are loading the content...
Please wait, while we are loading the content...
| Content Provider | World Health Organization (WHO)-Global Index Medicus |
|---|---|
| Author | Oshita, M. Kigoshi, S. Muramatsu, I. |
| Description | Author Affiliation: Oshita M ( Department of Pharmacology, Fukui Medical School, Japan.) |
| Abstract | 1. alpha 1-Adrenoceptor subtypes in rabbit thoracic aorta have been examined in binding and functional experiments. 2. [3H]-prazosin bound to two distinct populations of alpha 1-adrenoceptors (pKD,high = 9.94, Rhigh = 79.2 fmol mg-1 protein; pKD,low = 8.59, Rlow = 215 fmol mg-1 protein). Pretreatment with chloroethylclonidine (CEC, 10 microM) almost inactivated the prazosin-high affinity sites and reduced the number of the low affinity sites without changing the pKD value. 3. In the displacement experiments with CEC-untreated membranes, unlabelled prazosin, WB4101 and HV723 displaced the binding of 200 pM [3H]-prazosin monophasically; the affinities for WB4101 (pK1 = 8.88) and HV723 (8.49) were about 10 times lower than that for prazosin (9.99). In the CEC-pretreated membranes also, the antagonists inhibited the binding of 1000 pM [3H]-prazosin monophasically; the pK1 values for prazosin, WB4101 and HV723 were 9.09, 8.97 and 8.17, respectively. These results suggest that the prazosin-high and low affinity sites can be independently appraised in the former and latter experimental conditions. Noradrenaline, but not methoxamine, showed slightly higher affinity for the prazosin-high affinity site than for the low affinity site. 4. In the functional experiments, noradrenaline (0.001-100 microM) and methoxamine (0.1-100 microM) produced concentration-dependent contractions. Pretreatment with CEC inhibited the contractions induced by low concentrations of noradrenaline but without effect on the responses to methoxamine. Prazosin inhibited the concentration-response curves for noradrenaline in the CEC-untreated aorta in a manner which was not consistent with competitive antagonism at a single site, and two distinct affinity constants(pKB = 9.71 and 8.74) were obtained. However, after CEC-pretreatment, Schild plots for prazosin were not significantly different from unity (pKB = 8.50). WB4101 and HV723 competitively inhibited the noradrenaline-induced contraction with low pKB values (approximately 8.30), irrespective of CEC pretreatment.Methoxamine-induced contractions were competitively inhibited by prazosin, WB4101 and HV723 with low pKB values similar to those obtained when noradrenaline was used as the agonist.These were not affected by CEC-pretreatment.5. The affinity constant for noradrenaline (pKA = 6.40) in CEC-untreated aorta was slightly greater than that obtained in CEC-pretreated aorta (5.78). On the other hand, methoxamine showed a similar affinity in CEC-untreated and pretreated aortae (pKA = approximately 4.5).6. Nifedipine (1 microM) slightly attenuated the contractile responses to noradrenaline and methoxamine in CEC-untreated and pretreated aortae, suggesting that nifedipine cannot discriminate between alpha 1-adrenoceptors involved in CEC-sensitive and -resistant contractions.7. From these results it is suggested that in the rabbit thoracic aorta there are two distinct alpha 1-adrenoceptor subtypes (presumably alpha 1B and alpha 1L subtypes according to recently proposed subclassification),both of which are involved in noradrenaline-induced contraction. The alpha 1L subtype predominantly mediates the contraction induced by methoxamine. |
| ISSN | 00071188 |
| e-ISSN | 14765381 |
| Journal | British Journal of Pharmacology |
| Issue Number | 4 |
| Volume Number | 108 |
| Language | English |
| Publisher | Wiley Online Library(on behalf of The British Pharmacological Society) |
| Publisher Date | 1993-04-01 |
| Publisher Place | Great Britain (UK) |
| Access Restriction | Open |
| Subject Keyword | Muscle, Smooth, Vascular Metabolism Receptors, Adrenergic, Alpha Drug Effects Adrenergic Alpha-Agonists Pharmacology Adrenergic Alpha-Antagonists Animals Aorta, Thoracic Binding, Competitive Clonidine Analogs & Derivatives In Vitro Techniques Methoxamine Muscle Contraction Norepinephrine Phenoxybenzamine Prazosin Rabbits Research Support, Non-U.S. Gov't |
| Content Type | Text |
| Resource Type | Article |
| Subject | Pharmacology |
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...
|