Isoproterenol-induced Cardiomyopathy Model
Objective: Assessment of isoproterenol-induced premature death and heart failure in transgenic mouse models with enhanced L-type Ca2+ channel activity, examining the role of mitochondrial-dependent cardiomyocyte necrosis
Protocol Steps
Transgenic mouse model generation and characterization
Inducible transgenic mice with enhanced sarcolemmal L-type Ca2+ channel (LTCC) activity were used as the primary model system
Note: These mice showed progressive myocyte necrosis leading to pump dysfunction and premature death
View evidence from paper
“Inducible transgenic mice with enhanced sarcolemmal L-type Ca2+ channel (LTCC) activity showed progressive myocyte necrosis that led to pump dysfunction and premature death”
Acute β-adrenergic receptor stimulation
Acute stimulation of β-adrenergic receptors was applied to transgenic mice, which dramatically enhanced myocyte necrosis and cardiomyopathy effects
Note: This stimulation enhanced the effects of enhanced Ca2+ influx
View evidence from paper
“effects that were dramatically enhanced by acute stimulation of β-adrenergic receptors”
Isoproterenol treatment
Isoproterenol was administered to induce premature death in transgenic mouse models
Note: Loss of cyclophilin D blocked isoproterenol-induced premature death
View evidence from paper
“loss of cyclophilin D, a regulator of the mitochondrial permeability transition pore that underpins necrosis, blocked Ca2+ influx–induced necrosis of myocytes, heart failure, and isoproterenol-induced premature death”
Pharmacological intervention with L-type Ca2+ channel blockers
L-type Ca2+ channel blockers were administered to test whether they could prevent enhanced Ca2+ influx-induced cellular necrosis and cardiomyopathy
Note: LTCC blockers successfully prevented necrosis and heart failure
View evidence from paper
“Enhanced Ca2+ influx–induced cellular necrosis and cardiomyopathy was prevented with either LTCC blockers or β-adrenergic receptor antagonists”
Pharmacological intervention with β-adrenergic receptor antagonists
β-adrenergic receptor antagonists were administered to test whether they could prevent enhanced Ca2+ influx-induced cellular necrosis and cardiomyopathy
Note: β-adrenergic receptor antagonists successfully prevented necrosis and heart failure
View evidence from paper
“Enhanced Ca2+ influx–induced cellular necrosis and cardiomyopathy was prevented with either LTCC blockers or β-adrenergic receptor antagonists”
Assessment of cyclophilin D knockout effects
Transgenic mice with loss of cyclophilin D were evaluated to determine the role of mitochondrial permeability transition pore regulation in heart failure and premature death
Note: Loss of cyclophilin D blocked Ca2+ influx-induced necrosis, heart failure, and isoproterenol-induced premature death
View evidence from paper
“loss of cyclophilin D, a regulator of the mitochondrial permeability transition pore that underpins necrosis, blocked Ca2+ influx–induced necrosis of myocytes, heart failure, and isoproterenol-induced premature death”
Assessment of Bcl-2 overexpression effects
Transgenic mice with Bcl-2 overexpression were evaluated to determine whether antiapoptotic factors could mitigate heart failure and death associated with excess Ca2+ influx
Note: Bcl-2 overexpression was ineffective in preventing heart failure and death
View evidence from paper
“overexpression of the antiapoptotic factor Bcl-2 was ineffective in mitigating heart failure and death associated with excess Ca2+ influx and acute β-adrenergic receptor stimulation”
Evaluation in additional mouse disease models
The paradigm of mitochondrial- and necrosis-dependent heart failure was tested in other mouse models of disease beyond the primary LTCC transgenic model
Note: Results supported the concept that heart failure involves both apoptosis and necrotic loss of myocytes
View evidence from paper
“This paradigm of mitochondrial- and necrosis-dependent heart failure was also observed in other mouse models of disease”