Increased sensitivity of ventricular myocardium to intracellular calcium-overload in Syrian cardiomyopathic hamster.
Papillary muscles of Syrian hamsters with morphologically defined cardiomyopathy (CM), and of control hamsters (Co) have been studied electrophysiologically. Co and CM muscles differ significantly in the following electrophysiological parameters: resting potential (-79.8 +/- 2.9 mV in Co, -74.3 +/- 5.5 mV in CM), action potential duration at 25% repolarization (30.0 +/- 3.6 ms in Co, 25.1 +/- 2.7 ms in CM), and at 90% repolarization (120.0 +/- 21.9 ms in Co, 171.6 +/- 24.1 ms in CM), upstroke velocity of phase 0 depolarization (73.7 +/- 12.8 V/s in Co, 48.4 +/- 8.7 V/s in CM). When superfused with K+-free solutions Co muscles did not show any oscillatory after-potentials up to 15 mmol/l CaCl2. In contrast to this CM muscles respond to K+-free superfusion with oscillatory afterpotentials, transient spontaneous activity and dramatically reduced upstroke velocity. CM muscles respond much more sensitively to an intracellular Ca2+ overload than Co preparations.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002118:Calcium / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D009202:Cardiomyopathies / Q000503:physiopathology*; D006224:Cricetinae; D004195:Disease Models, Animal; D004558:Electric Stimulation; D005260:Female; D006352:Heart Ventricles / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D008647:Mesocricetus; D010210:Papillary Muscles / Q000187:drug effects / Q000473:pathology; D011188:Potassium / Q000494:pharmacology
D011188:Potassium; D002118:Calcium