Death in ventricular fibrillation induced by isoproterenol in DOCA-salt pretreated rats preceded by changes in myocardial electrolytes.
Serum and tissue content of sodium, potassium, magnesium and calcium was determined in controls and desoxycorticosterone acetate (DOCA)-salt treated rats to determine whether electrolyte changes preceded the development of isoproterenol-induced death in ventricular fibrillation. Control Sprague Dawley, male rats, were injected subcutaneously (s.c.) with either saline (Group A) or actinomycin D (0.1 mg/kg; Group B) once daily for 4 days. Other rats received 20 mg of DOCA by implantation, drank normal saline and were injected with either saline (Group C) or actinomycin D (Group D) once daily for 4 days. In the first part of the experiment, it was determined that none of 15 rats from Group C died when challenged with isoproterenol (150 micrograms/kg, s.c.) six days later: however, 13 out of 15 rats from Group D died within 29.1 +/- 15.0 minutes (mean +/- S.D.) from isoproterenol injection. Myocardial sodium was elevated (48.8 +/- 3.8 versus 36.3 +/- 1.9) and potassium decreased (60.4 +/- 3.4 versus 70.6 +/- 3.3, meq/kg wet weight, mean +/- S.D.) in rats that had succumbed to isoproterenol. In the second part of the experiment serum and tissues were removed from control and DOCA-saline pretreated rats before they died in ventricular fibrillation, 20 minutes after isoproterenol. DOCA-saline pretreated rats were hypernatremic and hypokalemic and exhibited higher sodium and lower potassium in skeletal muscle than control rats. Isoproterenol elicited hypokalemia in all rats, but it only elevated sodium and decreased potassium content in the myocardium of rats of Group D, that were more prone to die in ventricular fibrillation. It is concluded that myocardial electrolyte changes precede the onset of ventricular fibrillation and may be associated with the development of this dysrhythmia.
D000818:Animals; D003609:Dactinomycin / Q000494:pharmacology; D003645:Death, Sudden / Q000209:etiology*; D003900:Desoxycorticosterone / Q000494:pharmacology*; D004573:Electrolytes / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000139:chemically induced* / Q000378:metabolism
D004573:Electrolytes; D003609:Dactinomycin; D003900:Desoxycorticosterone; D007545:Isoproterenol