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Abnormal mitochondrial L-arginine transport contributes to the pathogenesis of heart failure and rexoygenation injury.

Williams D, Venardos KM, Byrne M, Joshi M, Horlock D, Lam NT, Gregorevic P, McGee SL, Kaye DM - PLoS ONE (2014)

Bottom Line: However, the mechanism responsible for arginine transport into mitochondria and the effect of HF on such a process is unknown.This was accompanied by significantly lower NO production and higher 3-nitrotyrosine levels (both p<0.05).The role of mitochondrial L-arginine transport in modulating cardiac stress responses was examined in cardiomyocytes with mitochondrial specific overexpression of CAT-1 (mtCAT1) exposed to hypoxia-reoxygenation stress. mtCAT1 cardiomyocytes had significantly improved mitochondrial membrane potential, respiration and ATP turnover together with significantly decreased reactive oxygen species production and cell death following mitochondrial stress.

View Article: PubMed Central - PubMed

Affiliation: Heart Failure Research Group, Baker IDI Heart & Diabetes Institute, Melbourne, Australia.

ABSTRACT

Background: Impaired mitochondrial function is fundamental feature of heart failure (HF) and myocardial ischemia. In addition to the effects of heightened oxidative stress, altered nitric oxide (NO) metabolism, generated by a mitochondrial NO synthase, has also been proposed to impact upon mitochondrial function. However, the mechanism responsible for arginine transport into mitochondria and the effect of HF on such a process is unknown. We therefore aimed to characterize mitochondrial L-arginine transport and to investigate the hypothesis that impaired mitochondrial L-arginine transport plays a key role in the pathogenesis of heart failure and myocardial injury.

Methods and results: In mitochondria isolated from failing hearts (sheep rapid pacing model and mouse Mst1 transgenic model) we demonstrated a marked reduction in L-arginine uptake (p<0.05 and p<0.01 respectively) and expression of the principal L-arginine transporter, CAT-1 (p<0.001, p<0.01) compared to controls. This was accompanied by significantly lower NO production and higher 3-nitrotyrosine levels (both p<0.05). The role of mitochondrial L-arginine transport in modulating cardiac stress responses was examined in cardiomyocytes with mitochondrial specific overexpression of CAT-1 (mtCAT1) exposed to hypoxia-reoxygenation stress. mtCAT1 cardiomyocytes had significantly improved mitochondrial membrane potential, respiration and ATP turnover together with significantly decreased reactive oxygen species production and cell death following mitochondrial stress.

Conclusion: These data provide new insights into the role of L-arginine transport in mitochondrial biology and cardiovascular disease. Augmentation of mitochondrial L-arginine availability may be a novel therapeutic strategy for myocardial disorders involving mitochondrial stress such as heart failure and reperfusion injury.

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Related in: MedlinePlus

Mitochondrial [3H]-L-arginine uptake was measured in the presence of L-lysine (10 mM), NEM (200 µM) or antimycin (2 µM) (n = 5–7 per gp).Data is presented as mean ± SEM. *p<0.05 vs. control.
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pone-0104643-g003: Mitochondrial [3H]-L-arginine uptake was measured in the presence of L-lysine (10 mM), NEM (200 µM) or antimycin (2 µM) (n = 5–7 per gp).Data is presented as mean ± SEM. *p<0.05 vs. control.

Mentions: To corroborate the demonstration of CAT1 mitochondrial protein, we next evaluated the uptake of [3H] L-arginine in both models of HF. Preliminary L-arginine uptake time course studies over 30 minutes in isolated cardiac mitochondria demonstrated a progressive linear accumulation of [3H] L-arginine over time ranges from 1–25 minutes (R2 = 0.9905 data not shown) and accordingly an incubation time of 15 minutes was selected. In parallel we investigated mitochondrial respiration using the Seahorse platform. Mitochondrial viability was first confirmed by the presence of respiratory control ratios of ≥4. State 3 respiration, as assessed in the presence of succinate, was however significantly (p<0.05) decreased in mitochondria isolated from failing hearts compared to controls (997±117 vs 1726±198 pmol O2/min). As shown in Figure 2, there was a concentration dependent increase in L-arginine uptake in mitochondria isolated from the normal heart. By contrast, L-arginine uptake was significantly reduced in mitochondria from failing sheep and mouse hearts when compared with healthy controls. L-arginine transport by sheep mitochondria from control animals was significantly reduced by the competitive inhibitor L-lysine (48%, p<0.05), NEM (37%, p<0.05) and antimycin (32%, p<0.05) as shown in Figure 3.


Abnormal mitochondrial L-arginine transport contributes to the pathogenesis of heart failure and rexoygenation injury.

Williams D, Venardos KM, Byrne M, Joshi M, Horlock D, Lam NT, Gregorevic P, McGee SL, Kaye DM - PLoS ONE (2014)

Mitochondrial [3H]-L-arginine uptake was measured in the presence of L-lysine (10 mM), NEM (200 µM) or antimycin (2 µM) (n = 5–7 per gp).Data is presented as mean ± SEM. *p<0.05 vs. control.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4128716&req=5

pone-0104643-g003: Mitochondrial [3H]-L-arginine uptake was measured in the presence of L-lysine (10 mM), NEM (200 µM) or antimycin (2 µM) (n = 5–7 per gp).Data is presented as mean ± SEM. *p<0.05 vs. control.
Mentions: To corroborate the demonstration of CAT1 mitochondrial protein, we next evaluated the uptake of [3H] L-arginine in both models of HF. Preliminary L-arginine uptake time course studies over 30 minutes in isolated cardiac mitochondria demonstrated a progressive linear accumulation of [3H] L-arginine over time ranges from 1–25 minutes (R2 = 0.9905 data not shown) and accordingly an incubation time of 15 minutes was selected. In parallel we investigated mitochondrial respiration using the Seahorse platform. Mitochondrial viability was first confirmed by the presence of respiratory control ratios of ≥4. State 3 respiration, as assessed in the presence of succinate, was however significantly (p<0.05) decreased in mitochondria isolated from failing hearts compared to controls (997±117 vs 1726±198 pmol O2/min). As shown in Figure 2, there was a concentration dependent increase in L-arginine uptake in mitochondria isolated from the normal heart. By contrast, L-arginine uptake was significantly reduced in mitochondria from failing sheep and mouse hearts when compared with healthy controls. L-arginine transport by sheep mitochondria from control animals was significantly reduced by the competitive inhibitor L-lysine (48%, p<0.05), NEM (37%, p<0.05) and antimycin (32%, p<0.05) as shown in Figure 3.

Bottom Line: However, the mechanism responsible for arginine transport into mitochondria and the effect of HF on such a process is unknown.This was accompanied by significantly lower NO production and higher 3-nitrotyrosine levels (both p<0.05).The role of mitochondrial L-arginine transport in modulating cardiac stress responses was examined in cardiomyocytes with mitochondrial specific overexpression of CAT-1 (mtCAT1) exposed to hypoxia-reoxygenation stress. mtCAT1 cardiomyocytes had significantly improved mitochondrial membrane potential, respiration and ATP turnover together with significantly decreased reactive oxygen species production and cell death following mitochondrial stress.

View Article: PubMed Central - PubMed

Affiliation: Heart Failure Research Group, Baker IDI Heart & Diabetes Institute, Melbourne, Australia.

ABSTRACT

Background: Impaired mitochondrial function is fundamental feature of heart failure (HF) and myocardial ischemia. In addition to the effects of heightened oxidative stress, altered nitric oxide (NO) metabolism, generated by a mitochondrial NO synthase, has also been proposed to impact upon mitochondrial function. However, the mechanism responsible for arginine transport into mitochondria and the effect of HF on such a process is unknown. We therefore aimed to characterize mitochondrial L-arginine transport and to investigate the hypothesis that impaired mitochondrial L-arginine transport plays a key role in the pathogenesis of heart failure and myocardial injury.

Methods and results: In mitochondria isolated from failing hearts (sheep rapid pacing model and mouse Mst1 transgenic model) we demonstrated a marked reduction in L-arginine uptake (p<0.05 and p<0.01 respectively) and expression of the principal L-arginine transporter, CAT-1 (p<0.001, p<0.01) compared to controls. This was accompanied by significantly lower NO production and higher 3-nitrotyrosine levels (both p<0.05). The role of mitochondrial L-arginine transport in modulating cardiac stress responses was examined in cardiomyocytes with mitochondrial specific overexpression of CAT-1 (mtCAT1) exposed to hypoxia-reoxygenation stress. mtCAT1 cardiomyocytes had significantly improved mitochondrial membrane potential, respiration and ATP turnover together with significantly decreased reactive oxygen species production and cell death following mitochondrial stress.

Conclusion: These data provide new insights into the role of L-arginine transport in mitochondrial biology and cardiovascular disease. Augmentation of mitochondrial L-arginine availability may be a novel therapeutic strategy for myocardial disorders involving mitochondrial stress such as heart failure and reperfusion injury.

Show MeSH
Related in: MedlinePlus