|Author||Nair, R. R. ♦ Nair, Preetha|
|Source||Sree Chitra Tirunal Institute for Medical Sciences & Technology|
|Subject Domain (in DDC)||Technology ♦ Medicine & health ♦ Diseases|
|Subject Domain (in MeSH)||Cardiovascular System ♦ Anatomy ♦ Cardiovascular Diseases ♦ Diseases|
|Abstract||Magnesium has attracted attention as an essential element with diverse roles in the regulation of cardiac contraction. Chronic suboptimal intake of the element results in hypomagnesaemia. Experimental and clinical studies indicate the possibility of a marginal decrease in myocardial magnesium compared to those with sufficient intake. Reduction in extracellular magnesium affects myocardial excitability and contractility predominantly, by modulation of the levels of other ions that have an influence on cardiac mechanics. Majority of the in vitro experiments in isolated ventricular tissue or myocytes record an inverse relation between Mg concentration and inotropic response, mediated probably by enhanced influx of Ca2+ promoting sarcoplasmic reticular Ca2+ release. Paradoxically myocardial contractility is usually compromised in animals on Mg deficient diet or on perfusion of whole heart with low Mg (< 0.5 mM) buffer. In the whole animal or organ, magnesium deficiency induced coronary vasospasm, defective energy metabolism and excessive free radical generation may be important variables acting in concert or independently to affect myocardial function. Electrical excitability is enhanced in magnesium deficiency, and arrhythmic changes are presumed to be mediated by disturbance in K+ homeostasis. Magnesium deficiency has not received the attention it deserves probably due to absence of clinical symptoms.Magnesium deficiency concomitant with stress may be of clinical significance, leading to arrhythmic, hemodynamic and ischaemic changes in the heart. Chronic magnesium deficiency is accompanied by increased free radical generation. Free radicals are known to influence myocardial excitability and contractility. Physiologic and pathologic stress also promotes free radical generation. The additive action of free radical generation in magnesium deficiency and any form of stress may be one of the reasons for enhanced sensitivity to stress in magnesium deficiency. Clinical and experimental data on the cardiac consequences of marginal magnesium deficiency being limited, a number of factors need experimental validation. For example- the extent of change in total and ionized magnesium in the serum and heart, mechanical response of the myocardium to decrease of total and ionized magnesium in the intra- and extracellular milieu; the extent of free radical generation in magnesium deficiency and the cardiac consequence; and also the additive effect of magnesium deficiency and different forms of stress.|
|Education Level||UG and PG|
|Learning Resource Type||Article|
|Educational Framework||Medical Council of India (MCI)|
Ministry of Human Resource Development (MHRD) under its National Mission on Education through Information and Communication Technology (NMEICT) has initiated the National Digital Library of India (NDLI) project to develop a framework of virtual repository of learning resources with a single-window search facility. Filtered and federated searching is employed to facilitate focused searching so that learners can find out the right resource with least effort and in minimum time. NDLI is designed to hold content of any language and provides interface support for leading vernacular languages, (currently Hindi, Bengali and several other languages are available). It is designed 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 being developed to help students to prepare for entrance and competitive examinations, 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 being developed at Indian Institute of Technology Kharagpur.
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 Human Resource Development (MHRD), through its National Mission on Education through Information and Communication Technology (NMEICT), has sponsored and funded the National Digital Library of India (NDLI) project.
For any issue or feedback, please write to email@example.com