Increased cardiac BNP expression associated with myocardial ischemia

Area of Science:

• Cardiology
• Molecular Biology
• Biochemistry

Background:

• Congestive heart failure is associated with increased cardiac brain natriuretic peptide (BNP) gene expression and elevated plasma levels of BNP and its precursor, proBNP.
• The role of myocardial ischemia, independent of overt heart failure, in regulating cardiac BNP expression requires further investigation.

Purpose of the Study:

• To investigate whether myocardial ischemia, in the absence of overt heart failure, contributes to increased myocardial BNP expression.
• To determine the relationship between myocardial BNP mRNA levels and plasma BNP/proBNP concentrations in different patient cohorts.

Main Methods:

• Real-time PCR was used to quantify BNP mRNA in myocardial biopsies from patients undergoing coronary bypass grafting.
• Radioimmunoassays measured plasma concentrations of BNP and proBNP.
• Patient groups included those with hypoxic myocardium, coronary artery disease with normal left ventricular function, and heart failure without coronary artery disease.

Main Results:

• Plasma BNP and proBNP concentrations showed a strong correlation with ventricular BNP mRNA levels in coronary bypass grafting patients.
• Patients with coronary artery disease but without left ventricular dysfunction exhibited significantly increased plasma BNP and proBNP concentrations.
• Atrial BNP mRNA levels did not correlate with plasma BNP or proBNP concentrations.

Conclusions:

• Myocardial ischemia, even without left ventricular dysfunction, can augment cardiac BNP gene expression.
• Elevated plasma BNP and proBNP concentrations may result from cardiac ischemia, not solely from heart failure.
• These findings suggest that BNP levels should be interpreted in the context of potential myocardial ischemia.