title: Circadian Variations in Blood Pressure, Heart Rate, and HR-BP Cross-Correlation Coefficient during Progression of Diabetes Mellitus in Rat.
abstract: Circadian changes in cardiovascular function during the progression of diabetes mellitus in the diabetes prone rat (BBDP) (n = 8) were studied. Age-matched diabetes-resistant rats (BBDR) served as controls. BP was recorded via telemetry in contiguous 4 hr time periods over 24 hours starting with 12 midnight to 4 am as period zero (P0). Prior to onset of diabetes BP was high at P0, peaked at P2, and then fell again at P3; BP and heart rate (HR) then increased gradually at P4 and leveled off at P5, thereby exhibiting a bipodal rhythm. These patterns changed during long-term diabetes. The cross-correlation coefficient of BP and HR was not significantly different across groups at onset, but it fell significantly at 9 months of duration of diabetes (BBDP: 0.39 ± 0.06; BBDR: 0.65 ± 0.03; P < .05). These results show that changes in circadian cardiovascular rhythms in diabetes mellitus became significant at the late stage of the disease.
authors.affiliation: Department of Physiology, College of Medicine, University of Lagos, 12003 Lagos, Nigeria.
authors.forename: Chikodi N
authors.initials: CN
authors.lastname: Anigbogu
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Williams
authors.forename: David R
authors.initials: DR
authors.lastname: Brown
authors.forename: Dennis L
authors.initials: DL
authors.lastname: Silcox
authors.forename: Richard O
authors.initials: RO
authors.lastname: Speakman
authors.forename: Laura C
authors.initials: LC
authors.lastname: Brown
authors.forename: Dennis G
authors.initials: DG
authors.lastname: Karounos
authors.forename: David C
authors.initials: DC
authors.lastname: Randall