Linked Life Data

7854342

Source:http://linkedlifedata.com/resource/pubmed/id/7854342

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1995-3-13
pubmed:abstractText
The effects of the cardiac glycoside dihydroouabain (DHO), and the ericaceous toxin grayanotoxin-I (GTX-I) on myocardial cellular sodium (Nai) concentrations were investigated using sodium-23 nuclear magnetic resonance (23Na NMR) spectroscopy at 30 degrees C in isolated perfused guinea-pig hearts. The Nai NMR signals from perfused Langendorff heart preparations were obtained by the modified inversion recovery (IR) method based on the previous observation that the spin-lattice relaxation time (T1) of the Nai (25 or 34 msec at 8.46 Tesla (T)) is much faster than that of extracellular sodium (64 msec at 9.4 T). Nai was estimated from the calibration curve of the frequency area of the 23Na NMR FT spectra plotted against the standard Na concentration. The Nai concentration of the heart increased concomitantly with the positive inotropic effects (PIE) of DHO, GTX-I and monensin (MON). The cumulative sequential addition of DHO (5 x 10(-6) M), GTX-I (7 x 10(-8) M) and MON (5 x 10(-6) M), each of which alone induced no appreciable PIE, produced a 22% elevation in Nai concentration relative to that of the control (100%) accompanying a PIE of 44%. The mechanism of this Nai elevation induced by combinational addition of DHO, GTX-I and MON may be mediated as follows: GTX-I increases the net Na-influx via Na+ channels; DHO inhibits the pumping out of Na+ from the cell; and MON transports external Na+ into the cell, acting as a sodium ionophore. Consequently, these drugs act synergistically to increase the Nai, thereby increasing the intracellular Ca2+ concentration via Na(+)-Ca2+. exchange.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0300-8177
pubmed:author
pubmed:issnType
Print
pubmed:day
12
pubmed:volume
139
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
59-70
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
Direct measurement of increased myocardial cellular 23Na NMR signals in perfused guinea-pig heart induced by dihydroouabain and grayanotoxin-I.
pubmed:affiliation
Department of Pharmacology, Aichi Medical University, Japan.
pubmed:publicationType
Journal Article, Comparative Study, In Vitro, Research Support, Non-U.S. Gov't