Uptake of catecholamines by human cardiac muscle in

SUMMARY A trihydroxyindole fluorescent technique was used to measure the concentration of cate-cholamines in heart muscle taken from 42 patients undergoing open heart surgery. Noradrenaline was the dominant catecholamine and its depletion in the failing heart was confirmed. The distribution of cate-cholamines within the heart was such that the highest value, 2-64 + 0-68,ug/g, was found in the non-failing right atrium and the lowest, 0 53 ± 0 40 Ktg/g, in the failing left ventricle. The effects of sympathetic stimulation on the heart are mediated by the neurotransmitter, noradrenaline. This catecholamine is present in relatively large quantities in heart muscle but its concentration is reduced in patients with heart failure (Chidsey et al., 1963; Gertler et al., 1970; DeQuattro et al., 1973). Little is known about the concentration and dis-tribution of catecholamines in normal heart muscle. The data presented in this paper suggest that the myocardial catecholamine concentration may b