Some functional changes in experimentally induced cardiac overload.

In connection with the elucidation of the mechanisms of the acute and chronic haemodynamic stress during cardiac overloading, as well as in investigations on the role of neurotransmitter systems in the genesis of myocardial hypertrophy (MH), we carried out a complex of studies involving modelling of MH induced by treatment of rats with isoprenaline (ISO.) and of rabbits with thyreotom (Tri-iodothyronin +L-Thyroxin). With a view to studying some pathogenetic factors participating in the characteristics of the reproduced pathological states, combinations with oxprenolol, atropine, phentolamine (Phent.) and amino-oxyacetic acid (AOAA), which is a GABA-inhibitor, were also applied. The results of the ECG studies performed are the main object of the present article. Marked MH was found in rats injected for 12 days with Iso. in doses of 2 mg/kg, as well as in rabbits which received thyreotom (accompanied with development of arterial hypertension). Considerable functional and morphological damage (with subendocardial fibrous proliferations) were discovered in rats treated with Iso. +Phent. The combinations of oxprenolol and AOAA manifested a protective effect to rabbits with thyrotoxic disturbances. Evident is also the essential role played by the adrenergic mechanisms in MH pathogenesis.