Auricular Tyrosine Hydroxylase and Dopamine‐β‐Hydroxylase Activities and Noradrenaline Content in Ischaemic Heart Disease

Assessments were made of the tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DBH) activities as well as the noradrenaline (NA) content of samples excised from right auricular tissue during cardiac surgery on a total of 55 patients with ischaemic heart disease (IHD), valvular heart disease (VHD), uncomplicated atrial septal defect (ASD) or congestive heart failure (CHF). The NA content was significantly higher in the IHD group than in the other three groups. The TH activity was highest in the IHD group although the difference was statistically significant only compared with the ASD and CHF groups. The DBH activity was also highest in the IHD group, but again the difference was statistically significant only compared with the ASD and CHF groups. In the whole material there was a significant positive correlation between the NA content and TH or DBH activity, as well as between TH and DBH activity. In the IHD group there was a significant positive correlation between heart volume and TH activity. The results suggest that at least compared with ASD and CHF, the sympathetic tone is relatively high in IHD, possibly involving an enhanced NA turnover.