Effects of pharmacological manipulation of the renin-angiotensin system on the hibernation cycle of the 13-lined ground squirrel (Spermophilus tridecemlineatus).
Adult 13-lined ground squirrels were monitored for body temperature and state of torpor or arousal in a cold room at photoperiod LD 2:22 after receiving intraperitoneal injections of 0.9% saline vehicle or with the vehicle plus various test drugs. Saline injections (200 microliter) caused arousal of over 70% of the squirrels within 6 hours. Concomitant injections with Asp1 Val5 Angiotensin II (10 micrograms/kg, IP), however, significantly delayed arousal. This delaying effect was eliminated by simultaneous injections of the angiotensin II receptor antagonist, sarlasin (Sar1-Ala8-Ang II; 50 micrograms/kg, IP), In addition, 30 hours after induced arousal, the group receiving nonapeptide angiotensin I converting enzyme inhibitor (SQ 20, 881; 3 mg/kg) exhibited a significantly enhanced reentry into torpor. These data suggest that arousal from the reentry into torpor may be involved with renal function and the renin-angiotensin system. However, there appears to be temporal changes in the effect of angiotensin on torpor. Possible mechanisms, including the antagonistic effect of melatonin on angiotensin are discussed.
D000804:Angiotensin II / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002216:Captopril / Q000494:pharmacology; D006605:Hibernation / Q000187:drug effects; D012084:Renin-Angiotensin System / Q000187:drug effects; D012504:Saralasin / Q000494:pharmacology; D012589:Sciuridae; D013722:Teprotide / Q000494:pharmacology
D000804:Angiotensin II; C031193:angiotensin II, Asp(1)-Val(5)-; D002216:Captopril; D013722:Teprotide; D012504:Saralasin