Sophie Lalande1,2, Carly C Barron1, J Kevin Shoemaker3,4. 1. School of Kinesiology, Faculty of Health Sciences, Western University, Room 3110 Thames Hall, London, ON, N6A 5B9, Canada. 2. Department of Kinesiology, University of Toledo, Toledo, OH, USA. 3. School of Kinesiology, Faculty of Health Sciences, Western University, Room 3110 Thames Hall, London, ON, N6A 5B9, Canada. kshoemak@uwo.ca. 4. Department of Physiology and Pharmacology, Western University, London, ON, Canada. kshoemak@uwo.ca.
Abstract
PURPOSE: To determine the sex difference in the impact of central venous pressure (CVP) on the pressor response induced by ischemic handgrip exercise. METHODS: Twelve young healthy individuals (six males, 25 ± 3 years) performed ischemic handgrip exercise during mild levels of lower body negative pressure (LBNP, -5 mmHg) and during a 10° head-down tilt (HDT) to lower and increase CVP, respectively. The protocol consisted of 3 min of baseline ischemia, followed by 2 min of isometric handgrip exercise at 35 % of maximal voluntary contraction force, and 2 min of post-exercise circulatory occlusion. Mean arterial pressure (MAP) was assessed continuously by finger plethysmography and CVP was estimated from the venous pressure of the non-exercising dependent arm. RESULTS: Baseline CVP was greater during HDT than LBNP (8.4 ± 1.8 vs. 6.5 ± 1.8 mmHg, p < 0.01). MAP was greater during LBNP than HDT throughout the protocol (p = 0.05). During ischemic handgrip exercise, CVP increased in males but not in females (Group × protocol interaction: p = 0.01). A group × condition interaction was also observed for MAP, with males showing a greater MAP during LBNP than HDT (110 ± 2 vs. 103 ± 2 mmHg, p < 0.01). CONCLUSIONS: Baseline CVP inversely affected the pressor response to handgrip exercise in all individuals, with a greater MAP response observed during LBNP than HDT. Increase in CVP in males may be due to a greater splanchnic vasoconstrictor response to ischemic handgrip exercise. Therefore, combined baseline CVP and changes in CVP likely contributed to the greater MAP response observed during LBNP in males.
PURPOSE: To determine the sex difference in the impact of central venous pressure (CVP) on the pressor response induced by ischemic handgrip exercise. METHODS: Twelve young healthy individuals (six males, 25 ± 3 years) performed ischemic handgrip exercise during mild levels of lower body negative pressure (LBNP, -5 mmHg) and during a 10° head-down tilt (HDT) to lower and increase CVP, respectively. The protocol consisted of 3 min of baseline ischemia, followed by 2 min of isometric handgrip exercise at 35 % of maximal voluntary contraction force, and 2 min of post-exercise circulatory occlusion. Mean arterial pressure (MAP) was assessed continuously by finger plethysmography and CVP was estimated from the venous pressure of the non-exercising dependent arm. RESULTS: Baseline CVP was greater during HDT than LBNP (8.4 ± 1.8 vs. 6.5 ± 1.8 mmHg, p < 0.01). MAP was greater during LBNP than HDT throughout the protocol (p = 0.05). During ischemic handgrip exercise, CVP increased in males but not in females (Group × protocol interaction: p = 0.01). A group × condition interaction was also observed for MAP, with males showing a greater MAP during LBNP than HDT (110 ± 2 vs. 103 ± 2 mmHg, p < 0.01). CONCLUSIONS: Baseline CVP inversely affected the pressor response to handgrip exercise in all individuals, with a greater MAP response observed during LBNP than HDT. Increase in CVP in males may be due to a greater splanchnic vasoconstrictor response to ischemic handgrip exercise. Therefore, combined baseline CVP and changes in CVP likely contributed to the greater MAP response observed during LBNP in males.
Entities:
Keywords:
Cardiopulmonary receptors; Central blood volume; Handgrip exercise; Head-down tilt; Lower body negative pressure
Authors: Areum Kim; Shekhar H Deo; Lauro C Vianna; George M Balanos; Doreen Hartwich; James P Fisher; Paul J Fadel Journal: Am J Physiol Heart Circ Physiol Date: 2011-09-30 Impact factor: 4.733
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