Resistance to hypoxia-induced shortening of action potential duration of hypertrophied rabbit hearts.
Cardiac hypertrophy was induced in rabbits at atmospheric pressure by exposing them to hypoxia equivalent to an altitude of 6000 m for 280 to 350 h. Intracellular action potentials were recorded from Purkinje cells, and from atrial and papillary muscles, contractions of which were also measured. Hearts from normoxic littermates were used as controls. All the hypertrophied tissues studied had increased action potential durations (APD), but other electrophysiological parameters were little changed. During periods of acute exposure to hypoxia in vitro APD shortened less in the hypertrophied hearts than in the controls. During intervals of normoxia, interposed between the periods of acute hypoxia, recovery of contractions and of all electrophysiological changes was complete. It was concluded that the hypertrophy did not cause associated electrical alterations likely to increase the risk of arrhythmias.
D000200:Action Potentials; D000208:Acute Disease; D000531:Altitude; D000818:Animals; D006332:Cardiomegaly / Q000209:etiology / Q000503:physiopathology*; D004594:Electrophysiology; D006321:Heart / Q000503:physiopathology*; D000860:Hypoxia / Q000150:complications*; D009200:Myocardial Contraction; D011817:Rabbits; D013997:Time Factors