title: Haemodynamic changes in the cardiovascular system during the early phases of orthostasis.
abstract: In this study, we monitored the changes in arterial blood pressure continuously in two groups of Caucasian men during normal passive orthostasis as well as reversed passive orthostasis. Group A consisted of a group of 23 younger men (16 +/- 0.5 years) and group B consisted of 21 older men (62.9 +/- 2.7 years). The normal passive orthostatic test and the reversed passive orthostatic test were used to induce blood pressure changes. We found that the temporary and initial changes in blood pressure during the normal and reversed orthostatic tests were significantly lower in the older group. Heart rate increases were also lower in the older group. These findings could be explained in terms of a reduced compliance of the thin walled venous blood vessels in the elderly.
authors.affiliation: Department of Physiology, Potchefstroom University for Christian Higher Education, Potchefstroom, South Africa.
authors.forename: H W
authors.initials: HW
authors.lastname: Huisman
authors.forename: P J
authors.initials: PJ
authors.lastname: Pretorius
authors.forename: J M
authors.initials: JM
authors.lastname: Van Rooyen
authors.forename: N T
authors.initials: NT
authors.lastname: Malan
authors.forename: F C
authors.initials: FC
authors.lastname: Eloff
authors.forename: P J
authors.initials: PJ
authors.lastname: Laubscher
authors.forename: H S
authors.initials: HS
authors.lastname: Steyn
mesh_terms: D000293:Adolescent; D000375:Aging / Q000502:physiology*; D001158:Arteries / Q000502:physiology; D017704:Baroreflex / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D002320:Cardiovascular Physiological Phenomena; D003187:Compliance; D006801:Humans; D007024:Hypotension, Orthostatic / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011187:Posture / Q000502:physiology*; D011311:Pressoreceptors / Q000502:physiology; D018667:Tilt-Table Test