Isoproterenol Challenge
Objective: To induce cardiac stress in VDR knockout mice and assess myocardial responses including changes in myocyte size, ventricular weight, fibrosis, and gene expression patterns
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Equipment1
Not specified • Not specified • Not specified • Not specified
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Protocol Steps
Isoproterenol infusion initiation
Begin 7-day continuous infusion of isoproterenol in VDR knockout mice and control mice
Note: Infusion method (osmotic pump, injection, etc.) not specified in text
View evidence from paper
“7-day infusion of isoproterenol to induce cardiac stress in VDR knockout mice”
Echocardiographic assessment
Perform echocardiography to measure end diastolic and end systolic volumes
Note: Timing of echocardiography relative to infusion not specified
View evidence from paper
“reduction in end diastolic and end systolic volume by echocardiography”
Tissue collection and analysis
Collect cardiac tissue to measure myocyte size, left ventricular weight/body weight ratio, and interstitial fibrosis
Note: Specific timing of tissue collection not specified
View evidence from paper
“increase in myocyte size and left ventricular weight/body weight versus controls both at baseline and following a 7-day infusion”
Gene expression analysis
Analyze cardiac tissue for fetal gene program activation including atrial natriuretic peptide, alpha skeletal actin, and MCIP 1 expression
Note: Specific methodology (qPCR, microarray, etc.) not specified
View evidence from paper
“activation of the fetal gene program (i.e. increased atrial natriuretic peptide and alpha skeletal actin gene expression) and increased expression of MCIP 1”
Neonatal cardiomyocyte treatment
Treat isolated neonatal cardiomyocytes with 1,25-dihydroxyvitamin D and assess effects on isoproterenol-induced MCIP 1 expression
Note: Concentration of vitamin D and isoproterenol not specified; culture conditions not specified
View evidence from paper
“Treatment of neonatal cardiomyocytes with 1,25-dihydroxyvitamin D partially reduced isoproterenol-induced MCIP 1 mRNA and protein levels”
Gene promoter activity assessment
Measure MCIP 1 gene promoter activity in treated neonatal cardiomyocytes
Note: Specific methodology (luciferase assay, etc.) not specified
View evidence from paper
“MCIP 1 gene promoter activity”