Download Diet and Surviving Heart Disease

Skeletal muscle incorporation of n-3 fatty
acids increases oxygen efficiency and
reduces fatigue during repetitive muscle
contractions in the rat autoperfused
contracting hindlimb
Gregory E Peoples, Peter L McLennan, Alice J Owen
Smart Foods Centre, Department of Biomedical Science
University of Wollongong
ARC Key Centre of Teaching and Research
University of Wollongong
Oxidation Paradox
1.
n-3 PUFA
2.
• highly oxidisable
•
• fish oil feeding
•
= tissue incorporation
but
• no clinical evidence of •
associated adverse health
effects
Exercise
Creates oxidation
Muscle fatigue / soreness
but
Regular exercise reduces
muscle soreness / fatigue
ARC Key Centre of Teaching and Research
University of Wollongong
Membrane incorporation of long
chain n-3 PUFA
1. Composition of cell membrane is reflective of dietary fatty acid
profile
2. In heart, membrane n-3 PUFA incorporation
• reduces ventricular arrhythmia
• lowers myocardial oxygen consumption
• reduces heart rate
[isolated hearts indicate direct intra-cardiac effects]
ARC Key Centre of Teaching and Research
University of Wollongong
Skeletal muscle shows some similar incorporation
patterns to heart membrane
Fatty Acid
Control
Fish Oil
20:4n-6
RBC
Arachidonic Acid Heart
Skeletal
19.01 + 1.17
22.73 + 2.11
11.08 + 3.37
18.72 + 2.53
13.16 + 1.70*
7.14 + 1.54*
22:6n-3
DHA
1.92 + 0.21
9.66 + 0.42
11.4 + 1.9
5.91 + 0.80*
23.72 + 2.6*
18.40 + 4.15*
RBC
Heart
Skeletal
ARC Key Centre of Teaching and Research
University of Wollongong
Hypothesis
• Skeletal muscle oxygen consumption is
modulated by dietary fish oil
• Skeletal muscle fatigue is modulated by
dietary fish oil
ARC Key Centre of Teaching and Research
University of Wollongong
Rat Autoperfused Hindlimb
Preparation Systemic
Perfusion
pressure
Ventilator
Hindlimb
venous
return
5
BP
6
Stimulator
Pump
10 10
0 0
3
4
7
Arterial & venous sampling
5 5
0 0
0 0
- 5 0 5 0 25 25 50 50 75 75 10 10 12 12
0 0 0 0 0 0 0 0 00 00 50 50
Gastrocnemius
Muscle Tension
ARC Key Centre of Teaching and Research
University of Wollongong
Baseline measures following 30minutes perfusion without
contraction
Minute ventilation (ml/min)
130±10
PaO2 (mmHg)
~100
SaO2 (%)
98±0.2
(a-v)O2 (ml/100ml)
4.8±0.5
Hindlimb VO2 (µmol/g/min)
0.31±0.03
Arterial glucose (mM)
6.2±0.34
Arterial lactate (mM)
1.7±0.09
Hindlimb perfusion pressure (mmHg)
102±5
ARC Key Centre of Teaching and Research
University of Wollongong
Dietary Period
Male wistar rats
2 weeks washout diet (Olive Oil)
Saturated Fat Diet
SF
Sunflower Seed Oil Diet
n-6
Fish Oil Diet
n-3
8 weeks
8 weeks
8 weeks
Rat hindlimb perfusion
& Phospholipid analysis
ARC Key Centre of Teaching and Research
University of Wollongong
Force Displacement (g)
Rat autoperfused hindlimb in vivo Developed tension during repetitive
twitch stimulation
200
175
150
125
100
75
50
25
0
peak
1/2 peak
0
50
100
150
200
250
300
350
400
time (s)
ARC Key Centre of Teaching and Research
University of Wollongong
Skeletal muscle (red and white) DHA profiles for SF, n-6 and n-3
groups after 8 weeks diet.
DHA: Percentage of
Total
30
20
a
a
b
b
b
10
0
Red
SF
n-6
n-3
b
White
a,b indicates p<0.05 between diets
ARC Key Centre of Teaching and Research
University of Wollongong
Repeat bout stimulus
Arterial and Venous Blood Samples
R1
30
10 minutes
minutes
E1
R2
E2
30
10 minutes
minutes
R3
30
minutes
E3
10 minutes
Stimulation: 7-1V, 1Hz, 0.05ms twitch duration
ARC Key Centre of Teaching and Research
University of Wollongong
Single bout prolonged stimulus
Arterial and Venous Blood Samples
30 minutes rest
30 minutes contraction
Flow: 2ml/minute
7-12V, 2Hz, 0.05ms
ARC Key Centre of Teaching and Research
University of Wollongong
Force Displacement (g)
Muscle Twitch
200
180
160
140
120
100
80
60
40
20
0
-20
0.0
Peak Contraction
0.1
0.2
0.3
0.4
Time (s)
ARC Key Centre of Teaching and Research
University of Wollongong
200
180
160
140
120
100
80
60
40
20
0
-20
0.0
Force Displacement (g)
Force Displacement (g)
Muscle Twitch
Peak Contraction
0.1
0.2
Time (s)
0.3
0.4
200
180
160
140
120
100
80
60
40
20
0
-20
0.0
50% Fatigue
0.1
0.2
0.3
0.4
Time (s)
ARC Key Centre of Teaching and Research
University of Wollongong
Single bout prolonged hypoxic stimulus
Arterial and Venous Blood Samples
30 minutes rest
30 minutes contraction
Flow: 1ml/minute
Flow: 2ml/minute
7-12V, 2Hz, 0.05ms
~14% O2
ARC Key Centre of Teaching and Research
University of Wollongong
Twitch tension development:
Twitch Tension (g/g)
Normoxia v Hypoxia
150
Normoxia
Hypoxia
**
100
50
*
0
0.5
1
2.5
5
10
15
20
25
30
Oxygen Consumption
(mol/g/min)
Time (minutes)
3
Normoxia
Hypoxia
**
2
*
*p<0.05 for diets
1
**p<0.05 for time
0
0.5
1
2.5
5
10
15
20
Time (minutes)
25
30
ARC Key Centre of Teaching and Research
University of Wollongong
Summary
Fish oil feeding
1. Increased skeletal muscle membrane incorporation of n-3
PUFA, specifically DHA.
During Normoxia:
2. Reduced fatigue during 10 and 30minutes muscle stimulation.
3. Maintained lower relative rise time, fall time, contraction
duration and maximum rate of tension development and
relaxation throughout 30minutes muscle stimulation.
4. Increased efficiency of oxygen use in relation to muscle twitch
tension development.
5. Improved recovery of muscle contraction.
6. Reduced muscle oxygen consumption during recovery.
ARC Key Centre of Teaching and Research
University of Wollongong
Summary
Fish oil feeding
During Hypoxia:
7. Reduced fatigue during 30minutes muscle stimulation.
8. Increased efficiency of oxygen use in relation to muscle twitch
tension development (v saturated fat).
9. Improved caffeine induced recovery of muscle contraction.
ARC Key Centre of Teaching and Research
University of Wollongong
Conclusion
• Dietary fish oil enhances fatigue resistance in
skeletal muscle.
• Dietary fish oil may be beneficial in reducing
oxygen flux during muscle contraction
potentially reducing oxidative stress and
protecting muscle during hypoxia.
ARC Key Centre of Teaching and Research
University of Wollongong