Abstract
We have previously shown that increased cardiac work initially caused a rapid Ca2+-independent fall of mitochondrial [NADH] ([NADH](m)) to a minimum level, and this was followed by a slow Ca2+-dependent recovery toward control level (Brandes and Bers, Biophys. J. 71:1024-1035, 1996; Brandes and Bers, Circ. Res. 80:82-87, 1997). The purpose of this study is to improve our understanding of the factors that control [NADH](m) during increased work. [NADH](m) was monitored using fluorescence spectroscopy in intact rat trabeculae isolated from the right ventricular wall. Work was increased by increasing sarcomere length, pacing frequency, external [Ca2+], or by decreased temperature. The results were: 1) The initial fall of [NADH](m) during increased pacing frequency depends independently on increased myofilament work and on increased Ca2+-transport ATPase activity. 2) The [NADH](m) recovery process depends on average cytosolic [Ca2+] (Av[Ca2+](c), but not on absolute work level. 3) The initial fall of [NADH](m) and the [NADH](m) recovery are similar whether increased work is associated with low frequency and high Ca2+-transient amplitude or vice versa (at the same myofilament work level and Av[Ca2+](c). 4) The mechanisms associated with the smaller fall and recovery of [NADH](m) at 37°C versus 27°C, may be explained by lowered Av[Ca2+](c) and myofilament work. The NADH control mechanisms that operate at lower temperature are thus qualitatively similar at more physiological temperatures.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1666-1682 |
| Number of pages | 17 |
| Journal | Biophysical Journal |
| Volume | 77 |
| Issue number | 3 |
| State | Published - Sep 1999 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Biophysics
Cite this
Analysis of the mechanisms of mitochondrial NADH regulation in cardiac trabeculae. / Brandes, Rolf; Bers, Donald M.
In: Biophysical Journal, Vol. 77, No. 3, 09.1999, p. 1666-1682.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Analysis of the mechanisms of mitochondrial NADH regulation in cardiac trabeculae
AU - Brandes, Rolf
AU - Bers, Donald M
PY - 1999/9
Y1 - 1999/9
N2 - We have previously shown that increased cardiac work initially caused a rapid Ca2+-independent fall of mitochondrial [NADH] ([NADH](m)) to a minimum level, and this was followed by a slow Ca2+-dependent recovery toward control level (Brandes and Bers, Biophys. J. 71:1024-1035, 1996; Brandes and Bers, Circ. Res. 80:82-87, 1997). The purpose of this study is to improve our understanding of the factors that control [NADH](m) during increased work. [NADH](m) was monitored using fluorescence spectroscopy in intact rat trabeculae isolated from the right ventricular wall. Work was increased by increasing sarcomere length, pacing frequency, external [Ca2+], or by decreased temperature. The results were: 1) The initial fall of [NADH](m) during increased pacing frequency depends independently on increased myofilament work and on increased Ca2+-transport ATPase activity. 2) The [NADH](m) recovery process depends on average cytosolic [Ca2+] (Av[Ca2+](c), but not on absolute work level. 3) The initial fall of [NADH](m) and the [NADH](m) recovery are similar whether increased work is associated with low frequency and high Ca2+-transient amplitude or vice versa (at the same myofilament work level and Av[Ca2+](c). 4) The mechanisms associated with the smaller fall and recovery of [NADH](m) at 37°C versus 27°C, may be explained by lowered Av[Ca2+](c) and myofilament work. The NADH control mechanisms that operate at lower temperature are thus qualitatively similar at more physiological temperatures.
AB - We have previously shown that increased cardiac work initially caused a rapid Ca2+-independent fall of mitochondrial [NADH] ([NADH](m)) to a minimum level, and this was followed by a slow Ca2+-dependent recovery toward control level (Brandes and Bers, Biophys. J. 71:1024-1035, 1996; Brandes and Bers, Circ. Res. 80:82-87, 1997). The purpose of this study is to improve our understanding of the factors that control [NADH](m) during increased work. [NADH](m) was monitored using fluorescence spectroscopy in intact rat trabeculae isolated from the right ventricular wall. Work was increased by increasing sarcomere length, pacing frequency, external [Ca2+], or by decreased temperature. The results were: 1) The initial fall of [NADH](m) during increased pacing frequency depends independently on increased myofilament work and on increased Ca2+-transport ATPase activity. 2) The [NADH](m) recovery process depends on average cytosolic [Ca2+] (Av[Ca2+](c), but not on absolute work level. 3) The initial fall of [NADH](m) and the [NADH](m) recovery are similar whether increased work is associated with low frequency and high Ca2+-transient amplitude or vice versa (at the same myofilament work level and Av[Ca2+](c). 4) The mechanisms associated with the smaller fall and recovery of [NADH](m) at 37°C versus 27°C, may be explained by lowered Av[Ca2+](c) and myofilament work. The NADH control mechanisms that operate at lower temperature are thus qualitatively similar at more physiological temperatures.
UR - http://www.scopus.com/inward/record.url?scp=0032818671&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0032818671&partnerID=8YFLogxK
M3 - Article
C2 - 10465777
AN - SCOPUS:0032818671
VL - 77
SP - 1666
EP - 1682
JO - Biophysical Journal
JF - Biophysical Journal
SN - 0006-3495
IS - 3
ER -