[Characteristics of reaction of the coronary vessels and metabolism of the myocardium in changing over from high to low frequency electric stimulation of the heart].
In 22 tests on an isolated dog's heart perfused from a donor the oxygen intake, coronary blood flow, oxyhemoglobin content in the coronary venous blood and arterio-venous difference were compared with a jumpwise and gradual depression of the electrostimulation of the heart rhythm from 4.5 down to 2.0-2.5 Hd. With an abrupt reduction of the contraction rhythm in the myocardium these persisted hypermetabolism outwardly resembling an acquintance of the oxygen debt, although the preceding work of the heart proceeded without any signs of hypoxia. There could be noted an elevated consumption of oxygen, an increased coronary circulation, a diminished utilization of lactic acid and even its ejection. Worthy of note is the fact that an elevated oxygen intake was ensured at the expense of the larger coronary circulation with a reduced extraction of oxygen, so that the saturation of the coronary venous blood with oxygen exceeded the initial values. With a gradual slowing down of the rhythm there were no manifestation of hypermetabolism: the consumption of oxygen returned back to its initial level, the coronary circulation decreased, while extraction of oxygen was rising. The data obtained are considered in the light of the metabolic hypothesis on the regulation of the vascular tone.
D000818:Animals; D003326:Coronary Circulation; D003331:Coronary Vessels / Q000502:physiology*; D004285:Dogs; D004558:Electric Stimulation; D006321:Heart / Q000502:physiology*; D007773:Lactates / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D010085:Oxidative Phosphorylation; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption; D010108:Oxyhemoglobins / Q000032:analysis
D007773:Lactates; D010108:Oxyhemoglobins; D010100:Oxygen
Osobennosti reaktsii venechnykh sosudov i metabolizma miokarda pri perekhode ot vysokikh chastot elektrostimuliatsii serdtsa k nizkim