Age-related changes in vasomotor reflex control of calf venous capacitance response to lower body negative pressure in humans

Qi Fu, Satoshi Iwase, Yuki Niimi, Atsunori Kamiya, Daisaku Michikami, Tadaaki Mano, Akio Suzumura

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8 Citations (Scopus)

Abstract

The present study was performed to test the hypothesis that calf venous capacitance would be reduced by mild gravitational stress through a vasomotor reflex in humans, and this response could be diminished with advancing age. Nine young (31±1 years, mean±SE) and 9 elderly (69±1 years) healthy males were exposed to a lower body negative pressure (LBNP) of 15 mmHg. Venous occlusion plethysmography was used to measure calf venous capacitance and calf blood flow. Muscle sympathetic nerve activity (MSNA) was recorded microneurographically from the tibial nerve along with cardiovascular variables. It was found that baseline MSNA was higher [21±4 (mean±SE) vs. 37±5 bursts· min-1, young vs. elderly; p<0.05] and calf venous capacitance was lower (1.71±0.12 vs. 1.44±0.10, ml·100ml-1, young vs. elderly; p< 0.05) in the elderly group. At 15mmHg-LBNP, heart rate and mean arterial pressure both remained unchanged, MSNA was enhanced, and calf blood flow was reduced in all subjects. Calf venous capacitance during LBNP decreased in the young, but did not change in the elderly. A significant negative correlation between percent changes in MSNA and percent changes in calf venous capacitance existed in the young group (y=-0.171x-11.863, r=-0.682; p=0.0432), but disappeared in the elderly group. The ratio of percent changes in calf venous capacitance to percent changes in MSNA was markedly lower in the elderly (p<0.01). In conclusion, these results substantiate our hypothesis that calf venous capacitance is reduced by mild LBNP through the vasomotor reflex, and this response is diminished in the elderly.

Original languageEnglish
Pages (from-to)69-76
Number of pages8
JournalJapanese Journal of Physiology
Volume52
Issue number1
DOIs
Publication statusPublished - May 11 2002
Externally publishedYes

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Keywords

  • Arterial baroreflex
  • Calf blood flow
  • Cardiopulmonary baroreflex
  • Gravitational stress
  • Muscle sympathetic nerve activity

ASJC Scopus subject areas

  • Physiology

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