NADH fluorescence of isolated ventricular myocytes: effects of pacing, myoglobin, and oxygen supply.
NADH fluorescence of isolated ventricular myocytes: effects of pacing, myoglobin, and oxygen supply.
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离体心室肌细胞的 NADH 荧光：起搏、肌红蛋白和供氧的影响。
DOI：
10.1016/s0006-3495(93)81058-0
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发表时间：
1993
影响因子：
3.4
通讯作者：
Wittenberg,BA
中科院分区：
文献类型：
--
作者：
White,RL;Wittenberg,BA
内源性荧光被用来测量在个别的，分离的大鼠心肌细胞的线粒体NAD的减少的程度。在365 nm处的短暂落射照射期间，从415和470 nm处的发射荧光测定NAD还原。用95%O2/5%CO2平衡的培养基灌注的静息肌细胞的NAD减少为27 +/- 3%（SE）（n = 78），与跳动的全心脏相当。增加细胞内Ca ~（2+）并不显著改变NAD的还原。在以5 Hz电起搏10 min的收缩肌细胞中，NAD还原可逆地降低至11 +/- 1%（n = 78）。氧摄取被刺激了五倍。有微小的变化，肌浆pH值测定的荧光羧基-α-萘酚或-1。然而，NAD还原在电起搏收缩反应中可逆性增加：（a）肌红蛋白用亚硝酸钠灭活（37 +/- 7%; n=48）;或（B）细胞分层更密集，用20% O2/5% CO2充气（48 +/- 3%; n=30）。我们的结论是：（a）在氧合良好的细胞中，随着工作的增加，NADH/NAD的比率降低;（B）当氧输送受限时，稳态NAD的减少随着工作的增加而增加;（c）功能性肌红蛋白确保了对工作细胞线粒体的氧供应。
Endogenous fluorescence was used to measure the extent of reduction of mitochondrial NAD in individual, isolated rat cardiac myocytes. NAD reduction was determined from emitted fluorescence at 415 and 470 nm during brief epi-illumination at 365 nm. NAD reduction of resting myocytes, superfused with medium equilibrated with 95% O2/5% CO2, was 27 +/- 3% (SE) (n = 78), comparable to that in beating whole heart. Increasing intracellular Ca2+ did not significantly change NAD reduction. NAD reduction decreased reversibly to 11 +/- 1% (n = 78) in contracting myocytes electrically paced at 5 Hz for 10min. Oxygen uptake was stimulated fivefold. There was minimal change in sarcoplasmic pH measured by fluorescence of carboxy-seminaphthorhodafluor-1. However, NAD reduction increased reversibly in response to electrically paced contractions when: (a) myoglobin was inactivated with sodium nitrite (37 +/- 7%; n=48); or (b) cells were more densely layered and gassed with 20% O2/5% CO2 (48 +/- 3%; n=30). We conclude that (a) the ratio NADH/NAD is decreased in well-oxygenated cells with increased work; (b) steady-state NAD reduction is increased with increased work when oxygen delivery is limited; and (c) functional myoglobin ensures an oxygen supply to the mitochondria of working cells.