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dc.contributor.authorKamerman, P.
dc.contributor.authorMitchell, D.
dc.contributor.authorHelen, L.
dc.identifier.citationKamerman P, Mitchell D, Laburn H. Circadian variation in the effects of nitric oxide synthase inhibitors on body temperature, feeding and activity in rats. PFLUGERS ARCHIVen_US
dc.description.abstractWe have investigated whether there is circadian variation in the effects of nitric oxide synthase inhibitors on body temperature, physical activity and feeding. We used nocturnally active Sprague-Dawley rats, housed at approximately 24 degrees C with a 12:12 h light:dark cycle (lights on 07:00 hours) and provided with food and water ad libitum. Nitric oxide synthesis was inhibited by intraperitoneal injection of the unspecific nitric oxide synthase inhibitor N-nitro- L-arginine methyl ester ( L-NAME, 100, 50, 25, 10 mg/kg), or the relatively selective inducible nitric oxide synthase inhibitor aminoguanidine (100, 50 mg/kg), during the day ( approximately 09:00 hours) or night ( approximately 21:00 hours). Body temperature and physical activity were measured using radiotelemetry, while food intake was calculated by weighing each animal's food before as well as 12 and 24 h after each injection. We found that daytime injection of L-NAME and aminoguanidine had no effect on daytime body temperature. However, daytime injection of both drugs did decrease nocturnal food intake ( P<0.05) and activity ( P<0.05). When injected at night, L-NAME reduced night-time body temperature ( P<0.01), activity ( P<0.05) and food intake ( P<0.05) in a dose-dependent manner, but night-time injection of aminoguanidine inhibited only night-time activity ( P<0.05). The effects of nitric oxide synthase inhibition on body temperature, feeding and activity therefore are primarily a consequence of inhibiting constitutively expressed nitric oxide synthase, and are subject to circadian variation.en_US
dc.description.sponsorshipThe authors are grateful to Graham Mitchell for performing the surgery, Lennox Nqobo and the staff of the Central Animal Service for technical assistance, and Andrea Fuller for comments on the manuscript.en_US
dc.rightsAttribution 3.0 United States*
dc.titleCircadian variation in the effects of nitric oxide synthase inhibitors on body temperature, feeding and activity in ratsen_US
dc.contributor.departmentSchool of Physiology, University of the Witwatersrand, Medical School, 7 York Road, Parktown, 2193, South Africa.en_US
dc.identifier.journalEuropean journal of physiologyen_US
dc.research.unitClosed Unitsen_US

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Attribution 3.0 United States
Except where otherwise noted, this item's license is described as Attribution 3.0 United States