[Pattern of excitation in isolated heart of hibernator ground squirrel Citellus undulatus].
Aim of our study was to measure conduction velocity and pattern of excitation during hypothermia in hearts of ground squirrels Citellus undulatus, known to be most resilient hibernators. We imaged electrical conduction in intact isolated hearts of summer active and winter hibernating ground squirrels at temperatures varying from +37 degrees C to +3 degrees C. Electrical activity was mapped using CCD camera (500 frames/sec) and voltage-sensitive dye di-4-ANEPPS during normal sinus rhythm and ventricular pacing. No spontaneous tachyarrhythmia was observed in all hearts at any temperature. Hearts were able to maintain spontaneous sinus rhythm and normal pattern of epicardial excitation throughout the whole range of studied temperatures. Despite responsiveness to pacing in all hearts ventricular conduction velocity was significantly reduced (about 10-fold) at low temperatures +3 degrees C. Our data provides the first direct demonstration that isolated heart of the summer active and winter hibernating ground squirrel Citellus undulatus is able to maintain normal excitation pattern in a range of temperatures from +37 degrees C to +3 degrees C.
Rozenshtraukh
L V
LV
Fedorov
V V
VV
Aliev
R R
RR
Glukhov
A V
AV
Mikheeva
T V
TV
Reznik
A V
AV
Efimov
I R
IR
D000818:Animals; D001831:Body Temperature / Q000502:physiology; D006329:Heart Conduction System / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006352:Heart Ventricles / Q000294:innervation; D006605:Hibernation / Q000502:physiology*; D066298:In Vitro Techniques; D012589:Sciuridae; D016276:Ventricular Function