We have shown that
aldosterone, previously thought to be synthesized solely in the adrenal cortex, is also produced in the failing human heart. One way to induce
aldosterone synthesis in the heart would be to increase the expression of
CYP11B2, the
enzyme catalyzing the terminal step in
aldosterone synthesis. However,
CYP11B2 expression has never been examined in cardiac tissue from patients with
heart failure. We assayed
CYP11B2 expression in left ventricular tissue obtained at autopsy from seven patients. Total
RNA was extracted from frozen samples.
CYP11B2 gene expression was then quantitatively analyzed using a modified real-time PCR method that enabled assay of samples containing very small amounts of template
DNA. The template
DNA was initially amplified 1024-fold by subjecting it to 10 PCR cycles in the absence of the TaqMan probe. Thereafter, conventional real-time PCR was simultaneously performed on both target and standard samples. We measured the small quantities of
CYP11B2 gene transcript and found the levels to be significantly higher in samples from
heart failure patients than in those from
cardiovascular disease-free patients. Our modified real-time PCR method enables quantitative analysis of gene expression using very small amounts of template
DNA.
CYP11B2 expression is up-regulated in the failing human heart.