Effects of lactate, reoxygenation, and fast drive on hypoxic, hyperkalemic, and acidotic Purkinje fibers.
The effects of hypoxia, hyperkalemia, and acidosis (HHA) and subsequent reoxygenation were studied in isolated canine Purkinje tissue. After 60-70 minutes of HHA, in the absence of exogenous lactate, reoxygenation reduced action potential duration (APD), increased amplitude, made maximum diastolic potential (Emax) more negative, increased diastolic depolarization rate (DD) of the action potential (AP), and increased developed force initially, compared to these values in the prehypoxic stage (control). In the presence of exogenous lactate (20-22 mmol) during HHA, reoxygenation after HHA leads to the development of afterdepolarization in the AP, prolongation of APD90, subsequent arrhythmia, cessation of developed force, and residual small potentials at a depolarized level. Higher stimulus voltage (by 70%) and higher driving rate (2 Hz) may restore normal APD and force sooner than when the rate of drive and the stimulus strength are kept unchanged.
Bhattacharyya
M L
ML
Department of Physiology, Meharry Medical College, Nashville, Tennessee.
Pattanayek
M
M
D000138:Acidosis / Q000503:physiopathology*; D000200:Action Potentials; D000818:Animals; D004285:Dogs; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006947:Hyperkalemia / Q000503:physiopathology*; D000860:Hypoxia / Q000503:physiopathology*; D066298:In Vitro Techniques; D007773:Lactates / Q000494:pharmacology*; D008297:Male; D009200:Myocardial Contraction; D010100:Oxygen / Q000494:pharmacology*; D011690:Purkinje Fibers / Q000187:drug effects / Q000503:physiopathology*
D007773:Lactates; D010100:Oxygen