Figueira 2014 Abstract MiP2014

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Mitochondrial respiration and calcium transport in rat tissues: conversely from skeletal muscle, heart and brain, isolated liver mitochondria exhibit gender dimorphism in respiratory activity.

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Figueira TR

Mitochondr Physiol Network 19.13 - MiP2014

Figueira TR, Chweih H, Castilho RF (2014)

Event: MiP2014

Previous data provided evidence that isolated liver mitochondria from female rats present higher rates of resting (LEAK) and ADP-stimulated (OXPHOS) O2 consumption than from male ones [1]. Furthermore, estrogens are cytoprotective, drive mitochondrial biogenesis and may modulate mitochondrial calcium homeostasis in brain and heart in in vitro models [2,3]. It is unknown whether such gender dimorphism occurs for other mitochondrial functions or in other tissues. Therefore, we aimed to study whether mitochondrial respiration and mitochondrial calcium influx and efflux rates exhibit tissue-specific gender dimorphism.

Liver, skeletal muscle, heart and brain mitochondria were isolated from female and male Wistar rats by differential centrifugation. Mitochondrial respiratory states were evaluated by high-resolution respirometry. Mitochondrial calcium transport (ruthenium red-sensitive initial influx at 25 ยตM external free calcium and sodium-dependent, at 15 mM sodium, and -independent efflux) was assessed by following external free calcium levels with the fluorescent probe CaGreen-5N under suitable conditions and in the presence of inhibitors of mitochondrial permeability transition. In isolated male mitochondria O2 fluxes (meanยฑSD nmolโˆ™min-1โˆ™mg-1) for OXPHOS and LEAK respectively, were: 37.6ยฑ9.8 and 8.6ยฑ2.6 in liver, 106.1ยฑ24.7 and 12.8ยฑ3.4 in skeletal muscle, 137.1ยฑ42.1 and 25.9ยฑ4.7 in heart, and 31.1ยฑ8.2 and 4.8ยฑ1.3 in brain. Calcium influx and sodium-dependent efflux respectively, were (meanยฑSD nmolโˆ™min-1โˆ™mg-1): 228.6ยฑ77.1 and 0.69ยฑ0.39 in liver, 56.12ยฑ20.5 and 3.31ยฑ0.67 in skeletal muscle, 39.4ยฑ18.6 and 8.25ยฑ1.42 in heart, and 54.6ยฑ23.9 and 2.25ยฑ0.89 in brain from males. Among the assessed respiratory and calcium transport variables, the only statistically significant (P<0.05) difference between genders occurred for liver mitochondrial OXPHOS capacity, which was 15% higher in female than in male rats.

We conclude that gender dimorphisms for the mitochondrial functions evaluated here is tissue-specific and is confined to higher maximal ADP-stimulated respiration in isolated liver mitochondria from female rats.


โ€ข O2k-Network Lab: BR Campinas Vercesi AE


Labels: MiParea: Respiration, Gender 

Stress:Permeability transition  Organism: Rat  Tissue;cell: Heart, Skeletal muscle, Nervous system, Liver  Preparation: Isolated mitochondria 

Regulation: Calcium 


HRR: Oxygraph-2k  Event: C2, Oral  MiP2014 

Affiliation

Dep Clinical Pathology, Fac Medical Sc, State Univ Campinas, Sรฃo Paulo, Brazil. - [email protected]

References

  1. Justo R, Boada J, Frontera M, Oliver J, Bermรบdez J, Gianotti M (2005) Gender dimorphism in rat liver mitochondrial oxidative metabolism and biogenesis. Am J Physiol Cell Physiol 289: 372-8.
  2. Morkuniene R, Arandarcikaite O, Ivanoviene L, Borutaite V (2010) Estradiol-induced protection against ischemia-induced heart mitochondrial damage and caspase activation is mediated by protein kinase G. Biochim Biophys Acta 1797: 1012-7.
  3. Nilsen J, Brinton RD (2003) Mechanism of estrogen-mediated neuroprotection: regulation of mitochondrial calcium and Bcl-2 expression. Proc Natl Acad Sci U S A 100: 2842-7.
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