TISSUE AND PLASMA PEPTIDASE ACTIVITY IS ALTERED DURING HYPOTHERMIC HIBERNATION IN THE 13 LINED GROUND-SQUIRREL (SPERMOPHILUS-TRIDECEMLINEATUS)

Adult 13 lined ground squirrels were monitored for entry into a state of hypothermic hibernation or arousal in a cold room on a photoperiod LD 2:22. Once animals developed predictable hibernation patterns, anim als were killed at the mid point of hypothermic hibernation or arousal for determination of plasma and tissue angiotensin-l-converting enzym e (Kininase II) activity. Enzyme was extracted from plasma, lung, kidn ey, liver, forebrain and brainstem and assayed in vitro. During hypoth ermic hibernation enzyme activity is significantly decreased in all ti ssues examined. These data suggest that the activity of tissue and pla sma peptidases are altered during the cyclic torporous periods charact eristic of hibernation in this species.