Abstract |
1. Ischaemia and anoxia induce excessive noradrenaline (NA) release in the heart by a mechanism independent of both nerve activity and extracellular Ca2+. The present study was designed to examine the potential role of intracellular Ca2+ mobilization in anoxic NA release in the heart by chelating intracellular free Ca2+. 2. In normoxic hearts, preloading with an intracellular free Ca2+ chelator ( BAPTA) reduced neuronal NA release by 65%, confirming the effectiveness of the loading protocol. Release of NA independent of nerve activity occurred in hearts subjected to a 40 min period of anoxic, substrate-free and nominal Ca(2+)-free perfusion. Loading hearts with BAPTA prior to anoxia failed to reduce NA overflow (1561 +/- 147 vs 1496 +/- 206 pmol/g over 40 min). Infusion with BAPTA (20 mumol/L) during the first 25 min of the anoxic period reduced the quantity of anoxic NA release by approximately 25% from 2013 +/- 124 to 1476 +/- 207 pmol/g (P < 0.05). 3. Our results confirm that anoxic NA release is predominantly a Ca(2+)-independent process with Ca2+ mobilization from endogenous storage playing only a minor contributing role.
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Authors | X J Du, A Bobik, M D Esler, A M Dart |
Journal | Clinical and experimental pharmacology & physiology
(Clin Exp Pharmacol Physiol)
Vol. 24
Issue 11
Pg. 819-23
(Nov 1997)
ISSN: 0305-1870 [Print] Australia |
PMID | 9363363
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Chelating Agents
- Egtazic Acid
- 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid
- Oxygen
- Calcium
- Norepinephrine
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Topics |
- Animals
- Calcium
(chemistry, metabolism)
- Chelating Agents
(chemistry)
- Egtazic Acid
(analogs & derivatives, chemistry)
- Electric Stimulation
- Heart
(innervation)
- Hypoxia
(metabolism)
- Male
- Myocardium
(metabolism)
- Norepinephrine
(metabolism)
- Oxygen
(metabolism)
- Rats
- Rats, Sprague-Dawley
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