Melatonin prevents the suppression of cardiac Ca2+-stimulated ATPase activity induced by alloxan

L. D. Chen, P. Kumar, R. J. Reiter, D. X. Tan, L. C. Manchester, J. P. Chambers, B. Poeggeler, S. Saarela

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35 Scopus citations


The effects of melatonin treatment on cardiac sarcolemmal membrane function were investigated in alloxan-injected rats. Ca2+-stimulated adenosinetriphosphatase (ATPase, Ca2+ pump) and Mg2+-ATPase activities were depressed significantly in sarcolemmal preparations from alloxan- injected rats compared with levels in control rats. These deficits were observed 2 days after alloxan injection, and they were accompanied by an increase in the density of voltage-sensitive calcium channels, as measured by the [3H]nitrendipine-binding assay. In a dose-dependent manner, treatment of rats with melatonin before alloxan injection significantly overcame the suppression of Ca2+-stimulated ATPase in cardiac sarcolemma. Melatonin (1, 5, and 10 mg/kg) overcame Ca2+-stimulated ATPase suppression by 13, 35, and 70%, respectively. In addition, melatonin at a dose of 10 mg/kg also prevented the suppression of the Mg2+-ATPase by 31%. The number of [3H]nitrendipine-binding sites was not influenced by melatonin. The patent Na+-K+-ATPase and ouabain-sensitive Na+-K+-ATPase activities were not different between the control and experimental groups. The results indicate that Ca2+ pump activity is suppressed by acute alloxan treatment, whereas the density of voltage-sensitive calcium channels is increased. These changes may be a consequence of alloxan toxicity to the cardiac sarcolemma. Melatonin, likely because of its antioxidant capacity, exerts a protective effect on heart sarcolemmal membrane function in alloxan-injected rats.

Original languageEnglish (US)
Pages (from-to)E57-E62
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Issue number1 30-1
StatePublished - 1994


  • [H]nitrendipine
  • alloxan
  • calcium channel
  • calcium ion-stimulated adenosinetriphosphatase
  • heart sarcolemma
  • magnesium ion- adenosinetriphosphatase
  • melatonin
  • sodium-potassium-adenosinetriphosphatase

ASJC Scopus subject areas

  • General Medicine


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