TY - JOUR
T1 - Diminished forearm vasomotor response to central hypervolemic loading in aerobically fit individuals
AU - Shi, Xiangrong
AU - Gallagher, Kevin M.
AU - Smith, Scott A.
AU - Bryant, Kristin H.
AU - Raven, Peter B.
N1 - Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 1996/11
Y1 - 1996/11
N2 - The aim of this study was to test the hypothesis that cardiopulmonary baroreflex control of forearm vascular resistance (FVR) during central hypervolemic loading was less sensitive in exercise trained high fit individuals (HF) compared to untrained average fit individuals (AF). Eight AF (age: 24 ± 1 yr and weight: 78.9 ± 1.7 kg) and eight HF (22 ± 1 yr 79.5 ± 2.4 kg) voluntarily participated in the investigation. Maximal aerobic power (determined on a treadmill), plasma volume and blood volume (Evans blue dilution method) were significantly greater in the HF than AF (60.8 ± 0.7 vs. 41.2 ± 1.9 ml · kg-1 · min-1, 3.96 ± 0.17 vs. 3.36 ± 0.08 l, and 6.33 ± 0.23 vs 5.28 ± 0.13 l). Baseline heart rate (HR), central venous pressure (CVP), mean arterial pressure (MAP, measured by an intraradial catheter or a Finapres finger cuff), forearm blood flow (FBF, plethysmography), and FVR, calculated from the ratio (MAP-CVP)/FBF, were not different between the HF and the AF. Lower body negative pressure (LBNP, -5, -10, -15, and -20 torr) and passive leg elevation (LE, 50 cm) combined with lower body positive pressure (LBPP, +5, +10, and +20 torr) were utilized to elicit central hypovolemia and hypervolemia, respectively. Range of CVP (from LBNP to LE + LBPP) was similar in the AF (from -3.9 to +1.9 mm Hg) and HF (from -4.0 to +2.2 mm Hg). However, FVR/CVP was significantly less in the HF (-1.8 ± 0.1 unit · mm Hg-1) than AF (-3.4 ± 0.1 unit · mm Hg-1). The FVR decrease in response to increase in CVP was significantly diminished in the HF (-1.46 ± 0.45 unit · mm Hg-1) compared to the AF (-4.40 ± 0.97 unit · mm Hg-1), and during LBNP induced unloading the FVR/CVP of the HF (-2.01 ± 0.49 unit · mm Hg-1) was less (P < 0.08) than the AF (-3.28 ± 0.69 unit · mm Hg-1). We concluded that the cardiopulmonary baroreceptor mediated FVR reflex response was significantly less sensitive to changes in CVP in individuals who practice exercise training.
AB - The aim of this study was to test the hypothesis that cardiopulmonary baroreflex control of forearm vascular resistance (FVR) during central hypervolemic loading was less sensitive in exercise trained high fit individuals (HF) compared to untrained average fit individuals (AF). Eight AF (age: 24 ± 1 yr and weight: 78.9 ± 1.7 kg) and eight HF (22 ± 1 yr 79.5 ± 2.4 kg) voluntarily participated in the investigation. Maximal aerobic power (determined on a treadmill), plasma volume and blood volume (Evans blue dilution method) were significantly greater in the HF than AF (60.8 ± 0.7 vs. 41.2 ± 1.9 ml · kg-1 · min-1, 3.96 ± 0.17 vs. 3.36 ± 0.08 l, and 6.33 ± 0.23 vs 5.28 ± 0.13 l). Baseline heart rate (HR), central venous pressure (CVP), mean arterial pressure (MAP, measured by an intraradial catheter or a Finapres finger cuff), forearm blood flow (FBF, plethysmography), and FVR, calculated from the ratio (MAP-CVP)/FBF, were not different between the HF and the AF. Lower body negative pressure (LBNP, -5, -10, -15, and -20 torr) and passive leg elevation (LE, 50 cm) combined with lower body positive pressure (LBPP, +5, +10, and +20 torr) were utilized to elicit central hypovolemia and hypervolemia, respectively. Range of CVP (from LBNP to LE + LBPP) was similar in the AF (from -3.9 to +1.9 mm Hg) and HF (from -4.0 to +2.2 mm Hg). However, FVR/CVP was significantly less in the HF (-1.8 ± 0.1 unit · mm Hg-1) than AF (-3.4 ± 0.1 unit · mm Hg-1). The FVR decrease in response to increase in CVP was significantly diminished in the HF (-1.46 ± 0.45 unit · mm Hg-1) compared to the AF (-4.40 ± 0.97 unit · mm Hg-1), and during LBNP induced unloading the FVR/CVP of the HF (-2.01 ± 0.49 unit · mm Hg-1) was less (P < 0.08) than the AF (-3.28 ± 0.69 unit · mm Hg-1). We concluded that the cardiopulmonary baroreceptor mediated FVR reflex response was significantly less sensitive to changes in CVP in individuals who practice exercise training.
KW - CARDIOPULMONARY BARORECEPTOR
KW - CENTRAL VENOUS PRESSURE
KW - EXERCISE TRAINING
KW - FOREARM BLOOD FLOW
KW - GAIN
KW - LEG ELEVATION
KW - LOWER BODY POSITIVE PRESSURE
UR - http://www.scopus.com/inward/record.url?scp=0029912626&partnerID=8YFLogxK
U2 - 10.1097/00005768-199611000-00007
DO - 10.1097/00005768-199611000-00007
M3 - Article
C2 - 8933489
AN - SCOPUS:0029912626
SN - 0195-9131
VL - 28
SP - 1388
EP - 1395
JO - Medicine and Science in Sports and Exercise
JF - Medicine and Science in Sports and Exercise
IS - 11
ER -