The role of catecholamines in myoglobin content increase in the myocardium

The mechanism of myoglobin content increase in the myocardium was investigated in experiments carried out in 33 mongrel dogs, weight 18-25 kg, divided into three groups: 1 -- with acute ischaemic myocardial infarction; 2 -- animals with mitral insufficiency, which were followed up for 6 to 12 month; 3 -- dogs which were over a protracted period given i.v. infusions of noradrenaline (2.3 micrograms/kg body weight/min). The amount of myoglobin in tissue samples was determined by spectrophotometry. In the 2nd and 3rd groups, there was a tendency towards an increase in myoglobin content in the left ventricle and a marked increase in the right ventricle; in the 1st group, an increase occurred predominantly in the right ventricle. In the same groups, the metabolism of catecholamines and their precursors was also investigated; it was found that the catecholamine synthesis was increased. The author advances the hypothesis that increased catecholamines secretion is one of the causes of the increase in myoglobin concentration in the heart muscle.