Thermoregulation During Hibernation: The Adjustable Thermostat
The general thesis of this book is that rebalancing and readjustment of ordinary mammalian control systems are responsible for the physiological achievements of hibernators. If this is correct, then the temperature changes of hibernators, as well as their weight cycles, should be consonant with this outlook. Strumwasser’s (1959a) continuous temperature recordings from California ground squirrels entering hibernation are in fact a perfect illustration of exaggerated adjustments in ordinary systems. During the summer, California ground squirrels become slightly cooler at night, as do other diurnal mammals. Then, toward the end of the active season these temperature drops become accentuated, reaching lower and lower levels, until finally the animal remains cool and does not arouse at all the next day. Figure 42 shows an example of these “test drops,” as Strumwasser called them. This curve is the epitomy and paradigm of hibernation phenomena. It is the most important curve in the hibernation literature of the last 50 years. And, as often happens with important findings, the general outlines of the entry into hibernation were known of long before the publication of Strumwasser’s (1959a) detailed account.
KeywordsHeat Production Ground Squirrel Preoptic Area Brain Temperature Test Drop
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