High levels of circulating catecholamines have been established as fundamental 
pathophysiological elements of heart failure (HF). However, it is unclear 
whether the increased gene expression of catecholamine-synthesis enzymes in the 
adrenal glands contributes to these hormone abnormalities in large animal HF 
models. We analyzed the mRNA levels of catecholamine-synthesizing enzymes: 
tyrosine hydroxylase (TH), aromatic L-amino acid decarboxylase (AAAD), 
dopamine-β-hydroxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT) 
in adrenal glands of 18 pigs with chronic systolic non-ischaemic HF 
(tachycardia-induced cardiomyopathy due to right ventricle pacing) and 6 
sham-operated controls. Pigs with severe HF demonstrated an increased expression 
of TH and DBH (but neither AAAD nor PNMT) as compared to animals with milder HF 
and controls (P<0.05 in all cases). The increased adrenal mRNA expression of TH 
and DBH was accompanied by a reduced left ventricle ejection fraction (LVEF) 
(P<0.001) and an elevated plasma B-type natriuretic peptide (BNP) (P<0.01), the 
other indices reflecting HF severity. There was a positive relationship between 
the increased adrenal mRNA expression of TH and DBH, and the high levels of 
circulating adrenaline and noradrenaline (all P<0.05). The association with 
noradrenaline remained significant also when adjusted for LVEF and plasma BNP, 
suggesting a significant contribution of adrenals to the circulating pool of 
catecholamines in subjects with systolic HF.