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Effects of Bedrest, Aging and Exercise Training on the Dynamic Starling Mechanism
Author(s) -
Shibata Shigeki,
Hastings Jeff,
Bhella Paul,
Pacini Eric,
Krainski Felix,
Palmer Dean,
VanGundy Tiffany,
Creson Daniel,
Fu Qi,
Zhang Rong,
Levine Benjamin D.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.970.8
Subject(s) - preload , medicine , cardiology , beat (acoustics) , blood pressure , hemodynamics , physics , acoustics
We assessed how physical activity and/or aging modify the dynamic Starling mechanism. Spectral transfer function gain between beat‐to‐beat changes in left ventricular end‐diastolic pressure (LVEDP) and stroke volume (SV) was used as an index of the dynamic Starling mechanism. Beat‐to‐beat pulmonary artery diastolic pressure (Swan‐Ganz catheter) was used as an index of beat‐to‐beat LVEDP. Beat‐to‐beat SV was calculated from finger arterial pressure with the Modelflow (Portapres). 1) A cross‐section of sedentary individuals 20–80 yrs old showed a linear relationship between the dynamic Starling mechanism index and age (Index=−0.022*Age+1.98, R=0.61 P<0.001). 2) Dynamic Starling mechanism indices in two elderly subjects (60 and 75 yrs old), who had been training (>150min/wk) for more than 25 yrs were 1.19 and 1.32. These were substantially higher than those predicted from their age. 3) A total of 14 subjects underwent 5‐wk head down bedrest; 11 with and 3 without exercise countermeasure (Ex and non‐Ex). Both the Ex and the non‐Ex showed a significant decrease of the dynamic Starling mechanism after bedrest while the magnitude of the decrease was lower in the Ex (−33%) than in the non‐Ex (−64%). These findings suggest unique parallels between bedrest deconditioning and aging in cardiovascular function; exercise training may be an effective countermeasure against both bedrest and aging. Supported by NSBRI and NIH