Species dependence of mitochondrial calcium transients during excitation-contraction coupling in isolated cardiomyocytes

被引:35
作者
Griffiths, EJ [1 ]
机构
[1] Univ Bristol, Bristol Royal Infirm, Inst Heart, Bristol, Avon, England
关键词
rat; guinea pig; mitochondria; calcium; indo-1; ruthenium red;
D O I
10.1006/bbrc.1999.1311
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Whether mitochondrial Ca2+ transport is rapid enough to respond to changes in cytosolic [Ca2+] ([Ca2+](c)) which occur during excitation-contraction coupling in the heart is controversial; different results were obtained with different techniques and different species. In this study mitochondrial [Ca2+] ([Ca2+](m)) was measured in indo-1/AM-loaded myocytes from rat and guinea-pig hearts where the cytosolic indo-1 had been removed by extended incubation of cells at 37 degrees C ("heat treatment"). The mitochondrial origin of the remaining fluorescence was confirmed by sensitivity of the indo-1 signal to ruthenium red. In resting rat myocytes, [Ca2+](m) was lower than [Ca2+](c), whereas in guinea-pig cells [Ca2+](m) was higher than [Ca2+](c). Upon electrical stimulation of cells, no change occurred in [Ca2+](m) in rat myocytes. However, in guinea-pig cells mitochondrial Ca2+ transients were clearly visible with a mean indo-1 ratio amplitude of 0.153 +/- 0.2 (n = 20), compared with 0.306 +/- 0.02 (n = 25), p < 0.001, prior to heat treatment. These observations suggest significant differences in mitochondrial Ca2+ transport in cardiomyocytes from different species. (C) 1999 Academic Press.
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页码:554 / 559
页数:6
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