Inverse temperature acclimation of heart rate in hibernating land snails

The heart rates of quiescent land snailsHelix lucorum andH. aspersa were recorded by impedance pneumography over several days. When snails acclimated to warm, humid, long days were transferred in late autumn to cool, dry, short days, in order to permit hibernation inverse rotational acclimation occurred, so that heart rates at low temperatures were lowered. However, temperature dependence increased so that heart rates at higher temperatures showed less difference. When hibernatingH. lucorum were brought into warm conditions and allowed to emerge from hibernation, their heart rates at low temperatures were raised. WarmacclimatedH. lucorum showed lower rates and higher temperature dependence before hibernation than after emergence: this may assist their entry into hibernation.H. lucorum showed a higher temperature dependence thanH. aspersa whether warm- or cold-acclimated: this may reflect the lower summer temperatures experienced by this population ofH. lucorum and the obligate nature of their winter dormancy.