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Effects of taurine and homocysteine on calcium homeostasis and hydrogen peroxide and superoxide anions in rat myocardial mitochondria.

Abstract：

:1. Taurine and homocysteine are metabolites of methionine. Hyperhomocysteinaemia is one of the risk factors for cardiovascular disease. Although taurine may be a cardiovascular cytoprotective substance, we hypothesized that it may antagonize the effects of homocysteine on myocardial mitochondrial function. 2. We studied the effects of taurine and homocysteine on [(45)Ca] uptake, Ca(2+)-ATPase activity and generation of hydrogen peroxide and superoxide anions in vitro in rat isolated myocardial mitochondria. 3. Results showed that the inhibition of mitochondrial [(45)Ca] uptake by homocysteine (0.1, 0.5 and 1.0 mmol/L) was concentration dependent. Taurine (5, 10 and 20 mmol/L) promoted [(45)Ca] uptake in a concentration-dependent manner, as well as concentration dependently reducing the homocysteine (0.5 mmol/L)-induced inhibition of mitochondrial [(45)Ca] uptake. 4. Homocysteine significantly inhibited mitochondrial Ca(2+)-ATPase activity, whereas taurine had a diphasic action on this activity. Taurine, at 5 and 10 mmol/L, increased Ca(2+)-ATPase activity (P < 0.01), but 20 mmol/L taurine inhibited Ca(2+)-ATPase activity (P < 0.05). Taurine attenuated the inhibitory effect of homocysteine on Ca(2+)-ATPase activity. 5. Homocysteine stimulated the generation of hydrogen peroxide and superoxide anions. Taurine had no effect on the generation of the anions, but inhibited their homocysteine-stimulated generation. 6. These results indicate that taurine and homocysteine have opposite effects in myocardial mitochondria with regard to [(45)Ca] uptake, Ca(2+)-ATPase activity and the generation of hydrogen peroxide and superoxide anions. Our results may show an important mechanism for the cardiovascular protective effects of taurine.

journal_name

Clin Exp Pharmacol Physiol

journal_title

Clinical and experimental pharmacology & physiology

authors

Chang L,Zhao J,Xu J,Jiang W,Tang CS,Qi YF

doi

10.1111/j.1440-1681.2004.03983.x

keywords:

subject

Has Abstract

pub_date

2004-04-01 00:00:00

pages

237-43

issue

eissn

0305-1870

issn

1440-1681

pii

CEP3983

journal_volume

pub_type

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Effects of taurine and homocysteine on calcium homeostasis and hydrogen peroxide and superoxide anions in rat myocardial mitochondria.