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Diabetes-Induced Apoptosis and Superoxide Generation is Reduced With Coenzyme Q10 Administration in a Mouse Model of Type 1 Diabetes
S78
Heart, Lung and Circulation 2012;21:S1–S142
CSANZ 2012 Abstracts
ABSTRACTS
187
188
Diabetes-Induced Apoptosis and Superoxide Generation is Reduced With Coenzyme Q10 Administration in a Mouse Model of Type 1 Diabetes
Disrupting Ca2+ Waves, But Not Ca2+ Leak, Protects Against Cardiac Arrhythmia
K. Huynh 1,2,∗ , H. Kiriazis 1 , X. Du 1 , J. Love 1 , K. JandeleitDahm 1 , J. McMullen 1,2 , R. Ritchie 1,2 1 Baker
IDI Heart & Diabetes Institute, Australia 2 Monash University, Department of Medicine, Australia Diastolic dysfunction is often the earliest manifestation of diabetic cardiomyopathy, usually accompanied by cardiac remodelling and increased oxidative stress. We tested the hypothesis that Coenzyme Q10 (CoQ) administration attenuates diabetes-induced left ventricular (LV) dysfunction and remodelling. Further, we aimed to compare the efficacy of CoQ to the ACEI ramipril. Male six week-old mice received either streptozotocin (STZ, 55 mg/kg/day i.p. for five days) or citrate buffer. After four weeks, mice were treated with either CoQ (10 mg/kg/day), olive oil vehicle, ramipril (3 mg/kg/day) or left untreated for eight weeks (n = 11–14/group). Diabetic mice had increased glucose and superoxide (O2 − ) production levels compared with non-diabetic animals. Diastolic dysfunction was evident on Doppler echocardiography (E/A ratio) and catheterisation (LV end diastolic pressure, EDP) in diabetic mice, which was also associated with cardiomyocyte hypertrophy (H&E staining), cardiac fibrosis (Sirius red staining) and increased apoptosis. Both CoQ and ramipril reduced these markers of adverse LV function and remodelling in diabetic mice; CoQ also significantly reduced the levels of superoxide production. Addition of CoQ to standard care may offer improved treatment of diastolic dysfunction in diabetic patients. Results
Citrate Sham
Blood glucose (mM) O2 − generation (RLU/s/mg) E/A ratio LVEDP (mmHg) Myocyte width (m) LV fibrosis (% of field) Apoptotic cells (AU)
10.2 ± 1.2
STZ Untreated 32.1 ± 1.1*
STZ + Olive oil 33.1 ± 0.5*
STZ + CoQ 33.0 ± 1.0*
14.1 ± 0.9
30.4 ± 1.5*
28.4 ± 2.9*
18.5 ± 2.2∧,# 21.3 ± 1.8*
1.8 ± 0.1 6.7 ± 0.3
1.3 ± 0.1* 10.2 ± 0.6*
1.4 ± 0.1* 9.9 ± 0.6*
12.9 ± 0.4
16.2 ± 0.7*
15.5 ± 0.4*
13.2 ± 0.3∧,# 14.0 ± 0.3∧,#
0.24 ± 0.0
0.75 ± 0.1*
0.88 ± 0.1*
0.51 ± 0.1*,∧,#0.48 ± 0.1*,∧,#
2.0 ± 0.3
8.8 ± 1.9*
8.5 ± 1.5*
∗
1.7 ± 0.1∧,# 7.7 ± 0.3∧,#
p < 0.05 vs citrate sham; one-way ANOVA.
∧
p < 0.05 vs STZ untreated; one-way ANOVA.
#
p < 0.05 vs STZ + olive oil; one-way ANOVA.
http://dx.doi.org/10.1016/j.hlc.2012.05.197
4.5 ± 0.7∧,#
STZ + Ramipril 32.5 ± 0.8*
1.6 ± 0.1 7.2 ± 0.4∧,#
4.0 ± 0.2∧,#
P. Jones 1,∗ , Y. Bai 2 , A. Vallmitjana 3 , R. Wang 2 , R. Clark 2 , Q. Zhou 2 , R. Benitez 3 , L. Hove-Madsen 4,5 , S. Chen 2 1 University
of Otago, Dunedin, New Zealand of Calgary, Calgary, Canada 3 Universitat Politenica de Catalunya, Barcelona, Spain 4 Cardiovascular Research Center CSIC, Barcelona, Spain 5 IIB Sant Pau, Hospital de Sant Pau, Barcelona, Spain 2 University
A common cause of cardiac arrhythmia is abnormal Ca2+ release through the cardiac ryanodine receptor (RyR2). This Ca2+ release occurs as either Ca2+ leak or Ca2+ waves. It is known that Ca2+ waves lead to delayed-after-depolarisations (DADs), which in turn trigger arrhythmias. As only Ca2+ waves and not Ca2+ leak per se produce DADs we hypothesised that disruption of the propagation of Ca2+ waves would prevent arrhythmia. To determine the effect of disrupting Ca2+ waves we crossed a RyR2 mutant mouse; RyR2-R4496C (known to have robust Ca2+ waves, DADs and arrhythmias) with a phospholamban-null (PLBKO) mouse (has Ca2+ leak but incapable of producing Ca2+ waves). Myocytes isolated from the resulting mouse (RC-PLBKO) displayed a high level of Ca2+ leak at physiological [Ca2+ ] in the form of Ca2+ sparks. Increasing the external [Ca2+ ] to 6 mM (where R4496C myocytes produce multiple Ca2+ waves) increased the level of Ca2+ leak without triggering Ca2+ waves. To determine whether the disruption of Ca2+ waves prevented DADs we recorded the membrane potential of RC-PLBKO myocytes at 6mM external [Ca2+ ]. We found that although the Ca2+ leak magnitude was similar to R4496C myocytes no DADs occurred. To confirm these findings in vivo we monitored the ECG from both R4496C and RC-PLBKO mice challenged with epinephrine and caffeine. Consistent with the cellular studies R4496C mice displayed severe arrhythmias whereas the RC-PLBKO maintained a normal sinus rhythm. These data suggest that the disruption of Ca2+ waves, rather than preventing Ca2+ leak, may be an effective strategy for preventing arrhythmias. http://dx.doi.org/10.1016/j.hlc.2012.05.198 189 Does Drug Therapy Prevent Sudden Cardiac Death in Patients with Heart Failure Compared with Implantable Cardioverter-Defibrillator? A Meta-Analysis of Randomised Controlled Trials K. Peck 1,∗ , Y. Lim 1,∗ , I. Hopper 1,2 , H. Krum 1,2 1 Department of Clinical Pharmacology, Alfred Hospital, Melbourne, Australia 2 Centre of Cardiovascular Research & Education in Therapeutics, Department of Epidemiology & Preventive Medicine, Monash University, Melbourne, Australia
Background: Patients with left ventricular systolic dysfunction (LVSD) are at high risk of sudden car-
Heart, Lung and Circulation 2012;21:S1–S142
CSANZ 2012 Abstracts
ABSTRACTS
187
188
Diabetes-Induced Apoptosis and Superoxide Generation is Reduced With Coenzyme Q10 Administration in a Mouse Model of Type 1 Diabetes
Disrupting Ca2+ Waves, But Not Ca2+ Leak, Protects Against Cardiac Arrhythmia
K. Huynh 1,2,∗ , H. Kiriazis 1 , X. Du 1 , J. Love 1 , K. JandeleitDahm 1 , J. McMullen 1,2 , R. Ritchie 1,2 1 Baker
IDI Heart & Diabetes Institute, Australia 2 Monash University, Department of Medicine, Australia Diastolic dysfunction is often the earliest manifestation of diabetic cardiomyopathy, usually accompanied by cardiac remodelling and increased oxidative stress. We tested the hypothesis that Coenzyme Q10 (CoQ) administration attenuates diabetes-induced left ventricular (LV) dysfunction and remodelling. Further, we aimed to compare the efficacy of CoQ to the ACEI ramipril. Male six week-old mice received either streptozotocin (STZ, 55 mg/kg/day i.p. for five days) or citrate buffer. After four weeks, mice were treated with either CoQ (10 mg/kg/day), olive oil vehicle, ramipril (3 mg/kg/day) or left untreated for eight weeks (n = 11–14/group). Diabetic mice had increased glucose and superoxide (O2 − ) production levels compared with non-diabetic animals. Diastolic dysfunction was evident on Doppler echocardiography (E/A ratio) and catheterisation (LV end diastolic pressure, EDP) in diabetic mice, which was also associated with cardiomyocyte hypertrophy (H&E staining), cardiac fibrosis (Sirius red staining) and increased apoptosis. Both CoQ and ramipril reduced these markers of adverse LV function and remodelling in diabetic mice; CoQ also significantly reduced the levels of superoxide production. Addition of CoQ to standard care may offer improved treatment of diastolic dysfunction in diabetic patients. Results
Citrate Sham
Blood glucose (mM) O2 − generation (RLU/s/mg) E/A ratio LVEDP (mmHg) Myocyte width (m) LV fibrosis (% of field) Apoptotic cells (AU)
10.2 ± 1.2
STZ Untreated 32.1 ± 1.1*
STZ + Olive oil 33.1 ± 0.5*
STZ + CoQ 33.0 ± 1.0*
14.1 ± 0.9
30.4 ± 1.5*
28.4 ± 2.9*
18.5 ± 2.2∧,# 21.3 ± 1.8*
1.8 ± 0.1 6.7 ± 0.3
1.3 ± 0.1* 10.2 ± 0.6*
1.4 ± 0.1* 9.9 ± 0.6*
12.9 ± 0.4
16.2 ± 0.7*
15.5 ± 0.4*
13.2 ± 0.3∧,# 14.0 ± 0.3∧,#
0.24 ± 0.0
0.75 ± 0.1*
0.88 ± 0.1*
0.51 ± 0.1*,∧,#0.48 ± 0.1*,∧,#
2.0 ± 0.3
8.8 ± 1.9*
8.5 ± 1.5*
∗
1.7 ± 0.1∧,# 7.7 ± 0.3∧,#
p < 0.05 vs citrate sham; one-way ANOVA.
∧
p < 0.05 vs STZ untreated; one-way ANOVA.
#
p < 0.05 vs STZ + olive oil; one-way ANOVA.
http://dx.doi.org/10.1016/j.hlc.2012.05.197
4.5 ± 0.7∧,#
STZ + Ramipril 32.5 ± 0.8*
1.6 ± 0.1 7.2 ± 0.4∧,#
4.0 ± 0.2∧,#
P. Jones 1,∗ , Y. Bai 2 , A. Vallmitjana 3 , R. Wang 2 , R. Clark 2 , Q. Zhou 2 , R. Benitez 3 , L. Hove-Madsen 4,5 , S. Chen 2 1 University
of Otago, Dunedin, New Zealand of Calgary, Calgary, Canada 3 Universitat Politenica de Catalunya, Barcelona, Spain 4 Cardiovascular Research Center CSIC, Barcelona, Spain 5 IIB Sant Pau, Hospital de Sant Pau, Barcelona, Spain 2 University
A common cause of cardiac arrhythmia is abnormal Ca2+ release through the cardiac ryanodine receptor (RyR2). This Ca2+ release occurs as either Ca2+ leak or Ca2+ waves. It is known that Ca2+ waves lead to delayed-after-depolarisations (DADs), which in turn trigger arrhythmias. As only Ca2+ waves and not Ca2+ leak per se produce DADs we hypothesised that disruption of the propagation of Ca2+ waves would prevent arrhythmia. To determine the effect of disrupting Ca2+ waves we crossed a RyR2 mutant mouse; RyR2-R4496C (known to have robust Ca2+ waves, DADs and arrhythmias) with a phospholamban-null (PLBKO) mouse (has Ca2+ leak but incapable of producing Ca2+ waves). Myocytes isolated from the resulting mouse (RC-PLBKO) displayed a high level of Ca2+ leak at physiological [Ca2+ ] in the form of Ca2+ sparks. Increasing the external [Ca2+ ] to 6 mM (where R4496C myocytes produce multiple Ca2+ waves) increased the level of Ca2+ leak without triggering Ca2+ waves. To determine whether the disruption of Ca2+ waves prevented DADs we recorded the membrane potential of RC-PLBKO myocytes at 6mM external [Ca2+ ]. We found that although the Ca2+ leak magnitude was similar to R4496C myocytes no DADs occurred. To confirm these findings in vivo we monitored the ECG from both R4496C and RC-PLBKO mice challenged with epinephrine and caffeine. Consistent with the cellular studies R4496C mice displayed severe arrhythmias whereas the RC-PLBKO maintained a normal sinus rhythm. These data suggest that the disruption of Ca2+ waves, rather than preventing Ca2+ leak, may be an effective strategy for preventing arrhythmias. http://dx.doi.org/10.1016/j.hlc.2012.05.198 189 Does Drug Therapy Prevent Sudden Cardiac Death in Patients with Heart Failure Compared with Implantable Cardioverter-Defibrillator? A Meta-Analysis of Randomised Controlled Trials K. Peck 1,∗ , Y. Lim 1,∗ , I. Hopper 1,2 , H. Krum 1,2 1 Department of Clinical Pharmacology, Alfred Hospital, Melbourne, Australia 2 Centre of Cardiovascular Research & Education in Therapeutics, Department of Epidemiology & Preventive Medicine, Monash University, Melbourne, Australia
Background: Patients with left ventricular systolic dysfunction (LVSD) are at high risk of sudden car-