Interaction of hyperbaric oxygenation with nifedipine and propranolol at the level of autonomic regulation of the heart in patients with angina pectoris

: Thirty three males suffering from coronary heart disease, Functional Classes II-III exercise-induced angina pectoris were examined for changes occurred in autonomic cardiac regulatory parameters under the influence of a normobaric oxygenation session (control), a hyperbaric oxygenation session (oxygen pressure 1.5 atm, duration 40 min), and combined normo- and hyperbaric oxygenation with nifedipine (oral corinfar, 20 mg, n = 18), and propranolol (oral inderal, 40 mg, n = 15) sessions. Variation of pulse and statistical analysis of cardiac rhythm were used in the study. The baseline autonomic tone and autonomic provision isometric exercise were evaluated. A single hyperbaric oxygenation session in this mode during isometric exercise was shown to diminish the sympathetic activation and increased heart rate which had been caused by nifedipine, by decreasing its central sympathetic effect and increasing neuroeffector cholinergic activity. The hyperbaric oxygenation session in combination with propranolol induced a supplementary reduction in sympathetic activity and its effects on cardiac rhythm via the humoral regulatory pathway by potentiating the negative chronotropic effect of the drug.