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The effect of plasma pH on proton kinetics of wrist flexor muscles following forearm and whole body exercise
Author(s) -
Volianitis Stefanos,
Secher Frederik,
Secher Niels H,
Quistorff Bjørn
Publication year - 2013
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.27.1_supplement.lb783
Subject(s) - rowing , intracellular ph , isometric exercise , chemistry , medicine , forearm , extracellular , endocrinology , anaerobic exercise , anatomy , physical therapy , biochemistry , archaeology , history
This study tested the hypothesis that clearance of protons from the muscles depends not only on the muscle to plasma proton gradient but also on plasma pH. Seven rowers (6 males; 23 ± 3 years; mean ± SD) performed, in random order, a maximal “2000 m” trial on a rowing ergometer and maximal rhythmic isometric handgrip contractions for 5 min. The variation of intracellular and extracellular pH of the wrist flexor muscle was evaluated using magnetic resonance spectroscopy (31P‐MRS) for 20 min of the recovery. Exercise elicited a decrease in intracellular pH from 7.0 ± 0.0 at rest to 6.3 ± 0.2 and 6.5 ± 0.1 (P < 0.05) during rowing and handgrip exercise, respectively. Also, rowing lowered arterial pH from 7.4 ± 0.0 to 7.1 ± 0.0 and forearm venous pH from 7.36 ± 0.03 to 6.95 ± 0.06 (all P < 0.05), while during handgrip exercise arterial pH was not different from rest (7.43 ± 0.01 to 7.39 ± 0.02) and venous pH decreased only from 7.39 ± 0.02 to 7.20 ± 0.04 (P < 0.05). Even though the rate of intracellular pH change was correlated with the intracellular to plasma pH gradient, the slope of this correlation was different (−0.6872 vs −0.0391 μM/min, handgrip vs rowing, respectively; P < 0.05). Thus, muscle proton elimination depends not only on the muscle to plasma gradient but also is attenuated by a low plasma pH, suggesting that proton clearance from working skeletal muscle cannot be explained by passive transport.