Activity of warm receptors inBoa constrictor raised at various temperatures
Nine young specimens ofBoa constrictor were raised for 4 years in a climatic chamber at an ambient temperature of 30°C under artificial illumination. Seven boas were raised at 23°C under the same conditions. At the end of the adaptation period, mean body weight of the warm adapted boas was 9.6±0.8 kg and that of the cold adapted ones 5.9±0.3 kg.
Static and dynamic activities of single specific trigeminal warm fibers were recorded when applying static temperatures of 20, 23, 26, 29, 32, 35 and 38°C and dynamic warming steps of 3°C, the initial temperatures being 20, 23, 26, 29, 32 and 35°C. Eighty-nine warm fibers were examined in the warm adapted and 62 fibers in the cold adapted group.
The average static frequencies between 29 and 35°C were higher in the warm adapted animals, the respective values for both groups at 32°C being 16.5 and 12s−1. The average peak frequencies for dynamic warming were 80s−1 for both groups, but the temperature of the dynamic maximum was shifted from 32°C in the warm adapted to 26°C in the cold adapted boas. At 32 and 35°C the average peak frequencies were higher in the warm adapted animals.
The whole fiber population contained various groups with static maxima between 23 and 35°C. Long-term adaptation modified mainly the static and dynamic discharge of the low-temperature fibers. The fiber group with a static maximum at 29°C showed a crossing of the static and dynamic frequency-temperature curves. In the higher temperature range the warm adapted animals had a higher and in the lower temperature range a lower static and dynamic frequency.
Key wordsWarm fibers Boa constrictor Long-term thermal adaptation Static discharge Dynamic discharge Infrared radiation
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