Myocardial catecholamines and their biosynthetic enzymes in various human heart diseases

Myocardial noradrenaline (NA) content, together with the activities of the enzymes tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) was measured in biopsy specimens taken during cardiac surgery from patients with various heart diseases. Fluorescence histochemical studies were also performed on comparable specimens. The mean NA content in patients with symptomatic ischaemic heart disease (IHD) was significantly higher than that in patients with valvular heart disease (VHD), atrial septal defect (ASD) or congestive heart failure (CHF). The lowest mean NA content was found in patients with CHF. The activities of TH and DBH were highest in the IHD group, although the differences between IHD and VHD groups were not significant. Histochemical investigations of adrenergic structures showed less fluorescence intensity in the CHF than in the other 3 groups. On the other hand, the density of the adrenergic nerve net and the size and number of varicosities were greatest in patients suffering from IHD. The significance of these results is discussed in relation to the pathophysiological mechanisms underlying these various disease conditions. In IHD the high myocardial NA content creates local conditions for excessive NA release into the myocardial interstitium at the onset of ischaemia, which is known to result in several adverse local consequences.