The hibernators heart Nature's response to arrhythmogenesis?

See article by Saitongdee et al. [1] (pages 108–115) in this issue. In this issue, Saitongdee et al. [1] describe an increase in connexin43, the major constituent of gap junctions in ventricular muscle [2], in hamsters ( Mesocricetus auratus ) exposed to circumstances that provoke hibernation of the animals. The hamsters were subjected to a temperature of 5°C in combination with 2 h of light per 24 h during a period of 8–10 weeks after a gradual transition from normal conditions to hypothermia. During control conditions the temperature was 20°C with a 8:16-h light/dark circadian photoperiod. Reduction of temperature and light period was 1°C and 30 min per day, respectively. This procedure led to the induction of hibernation in some, but not all animals. The latter were considered cold controls. Interestingly, the area density of connexin43 was 2.5 times as large in hibernators compared with controls (deduced from Fig. 2 in Ref. [1]) with the ‘cold controls’ in between. Both the number and the dimensions of the gap junctions increased. The increase in connexin43 was not only observed in the animals that actually hibernated, but also in the animals that did not, despite the presence of identical environmental stimuli. This suggests that the environmental stimuli and not primarily the body temperature (which was 5°C in hibernating animals and normal in ‘cold controls’) cause the increase in connexin43. Arousal, which is the biological term … * Corresponding author. Tel.: +31-30-253-8900; fax: +31-30-253-9036 t.opthof{at}med.uu.nl