Circadian timekeeping in hyperactive (wkha) and hypertensive (wkht)
inbred rat strains.
Rosenwasser, Alan M., Mark W. Pellowski, and Edith D. Hendley.
Department of Psychology, University of Maine, Orono, ME 04469,
Department of Molecular Physiology and Biophysics, University of
Vermont, Burlington, VT 05405
APStracts 3:0224R, 1996.
Inbred strains have been used to study genetic and physiological
relationships among different aspects of circadian timekeeping, as
well as relationships between circadian rhythmicity and other strain
-specific traits. The present study characterized several features of
circadian timekeeping in genetically hyperactive (WKHA) and
genetically hypertensive (WKHT) inbred strains, derived from
spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats. WKHAs
and WKHTs differed in free-running period, steady-state entrainment
to light-dark cycles, and photic phase-shifting; and relationships
among these measures were consistent with previous studies of
species, strain, and individual differences. Since both WKHTs and
SHRs show short circadian periods relative to their respective
comparison strains, this trait may cosegregate genetically with
hypertension. In contrast, since WKHAs and SHRs show similar photic
entrainment and phase-shifting, these circadian functions may
cosegregate with open-field hyperactivity. Finally, since neither
WKHAs nor WKHTs show the SHR's excessive levels of home-cage running
wheel activity, this trait is not related to either hypertension or
open-field activity. Further work would be required to elucidate
specific genetic and/or physiological linkages among these variables.
Received 22 November 1995; accepted in final form 5 April 1996.
APS Manuscript Number R734-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 28 June 96