title: Diurnal rhythms of blood pressure, heart rate, and locomotor activity in adult and old male Wistar rats.
abstract: The diurnal rhythms of systolic blood pressure (SBP), diastolic BP (DBP), heart rate (HR), and spontaneous locomotor activity (SLA) were determined in adult (6-month-old) and old (24-month-old) male Wistar rats by using radiotelemetry. The rhythm parameters (mesor, amplitude, acrophase, and percent rhythm) were analyzed by Fast-Fourier Transform and Cosinor methods. We found that the 12-h mean values of SBP, DBP, HR, and SLA were significantly (p<0.001) higher in the dark phase than in the light phase in both adult and old rats. The nocturnal 12-h mean value of HR was significantly (p<0.01) lower in old than in adult rats. In addition, the differences between diurnal and nocturnal 12-h mean values of SBP and HR were reduced in old rats. There was no significant difference in the 12-h mean values of SBP, DBP, and SLA between old and adult rats. Otherwise, the diurnal HR rhythm amplitude was significantly (p<0.01) reduced in old rats (32+/-2 vs. 46+/-2 bpm). A nearly 1-h delay in SBP and DBP acrophases (03h55 +/- 00h19 vs. 02h57 +/- 00h14 and 03h17 +/- 00h13 vs. 01h53 +/- 00h22, respectively) was found in old rats comparing to adult rats. No significant change in SLA diurnal rhythm was observed in old rats. In conclusion, these results show a decrease in the nocturnal 12-h mean value of HR and an alteration in cardiovascular diurnal rhythms by a 1-h delay of SBP and DBP acrophases and a reduction of HR rhythm amplitude in old Wistar rats.
authors.affiliation: Equipe d'Accueil/EA-2641, Department of Neuropharmacology, Faculty of Pharmacy, 31, Avenue Monge, 37200, Tours, France. bzhang@univ-tours.fr
authors.forename: B
authors.initials: B
authors.lastname: Zhang
authors.forename: F
authors.initials: F
authors.lastname: Sannajust
mesh_terms: D000375:Aging / Q000523:psychology*; D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D017440:Photoperiod; D051381:Rats; D017208:Rats, Wistar