AJP - Heart and Circulatory Physiology, Vol 253, Issue 5 1083-H1088, Copyright © 1987 by American Physiological Society
Monophasic action potentials during induced hypothermia in hedgehog and guinea pig hearts
G. Duker, P. O. Sjoquist and B. W. Johansson
Department of Pharmacology and Biochemistry, Hassle Cardiovascular Research Laboratories, Molndal, Sweden.
To evaluate mechanisms behind the difference in susceptibility to
ventricular fibrillation (VF) between the guinea pig and hedgehog heart,
the cardiac electrophysiology of the two species was studied at normal body
temperature and at different hypothermic levels by simultaneous recording
of the monophasic action potential (MAP) and the external electrocardiogram
(ECG). At normal body temperature, the duration of the ventricular MAP was
significantly shorter in the hedgehog (93 +/- 8.1 ms) than in the guinea
pig (138 +/- 2.6 ms). There was a distinct plateau phase in the guinea pig,
whereas no such phase could be detected in the hedgehog. During
hypothermia, a similar increase in MAP duration at full repolarization was
noticed for both species. However, the prolongation of the MAP at lower
repolarization levels was much less in the hedgehog. Besides,
hypothermia-induced slow conduction and dispersion of ventricular
repolarization was much more apparent in the guinea pig heart compared with
the hedgehog heart. These differences may be important factors in the
resistance to VF in the hedgehog, at normal body temperature and during
hypothermia.
