Decreased capacitance response with age in lower limbs of humans--a potential error in the study of cardiovascular reflexes in ageing

Research output: Contribution to journalArticle

Abstract

The cardiovascular regulation in humans depends to a major extent on sympathetic reflexes originating from volume receptors in the arterial as well as the cardiopulmonary region. With experimental approaches, such as lower body negative pressure (LBNP) and tilting, signs of reduced efficiency with ageing have been shown. However, a confounding factor may be an age-related decline in venous capacitance response of the lower limbs, reducing the decrease in central blood volume and thus the deactivation of baro/cardiopulmonary receptors. This potential error was addressed in the present study. Central hypovolaemic stress was produced by LBNP 60 cmH2O in 10 young (mean age 23, range 20-25 years) and 10 old males (mean age 65, range 61-70 years). Changes in tissue volume of the calf were studied by strain gauge volumetric technique. Transmission of negative pressure to the calf muscle was studied in two young and two old volunteers. The haemodynamic response to hypovolaemic circulatory stress was attenuated in the old as compared with the young subjects, with a less marked increase in heart rate and peripheral resistance. Further, in the old subjects, the decrease in systolic blood pressure, pulse pressure and forearm blood flow was attenuated. Transmission of negative pressure to the calf was equal in both groups. The capacitance response was reduced with age from 2.27 +/- 0.14 to 1.64 +/- 0.13 mL 100 mL-1 (P < 0.005). However, the net capillary fluid filtration was unchanged. The reduced capacitance function might partly explain the declining reflex responses with age in humans, and thus seems to be of considerable importance when studying cardiovascular sympathetic reflex responses in ageing.

Details

Authors
Organisations
External organisations
  • Skåne University Hospital
  • Lund University
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Physiology

Keywords

  • Adult, Aged, Aging/physiology, Blood Pressure/physiology, Capillaries/physiology, Cardiovascular System, Forearm/physiology, Heart Rate/physiology, Hemodynamics/physiology, Humans, Leg/blood supply, Lower Body Negative Pressure, Male, Middle Aged, Muscle, Skeletal/blood supply, Pulse, Reflex/physiology, Regional Blood Flow, Systole, Vascular Capacitance/physiology, Vascular Resistance/physiology
Original languageEnglish
Pages (from-to)503-7
Number of pages5
JournalActa Physiologica Scandinavica
Volume161
Issue number4
Publication statusPublished - 1997 Dec
Publication categoryResearch
Peer-reviewedYes