Regulation of human skeletal muscle perfusion and its heterogeneity during exercise in moderate hypoxia
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Regulation of human skeletal muscle perfusion and its heterogeneity during exercise in moderate hypoxia. / Heinonen, Ilkka H; Kemppainen, Jukka; Kaskinoro, Kimmo; Peltonen, Juha E; Borra, Ronald; Lindroos, Markus; Oikonen, Vesa; Nuutila, Pirjo; Knuuti, Juhani; Boushel, Robert Christopher; Kalliokoski, Kari K.
In: American Journal of Physiology: Regulatory, Integrative and Comparative Physiology, Vol. 299, No. 1, 01.07.2010, p. R72-9.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Regulation of human skeletal muscle perfusion and its heterogeneity during exercise in moderate hypoxia
AU - Heinonen, Ilkka H
AU - Kemppainen, Jukka
AU - Kaskinoro, Kimmo
AU - Peltonen, Juha E
AU - Borra, Ronald
AU - Lindroos, Markus
AU - Oikonen, Vesa
AU - Nuutila, Pirjo
AU - Knuuti, Juhani
AU - Boushel, Robert Christopher
AU - Kalliokoski, Kari K
PY - 2010/7/1
Y1 - 2010/7/1
N2 - Although many effects of both acute and chronic hypoxia on the circulation are well characterized, the distribution and regulation of blood flow (BF) heterogeneity in skeletal muscle during systemic hypoxia is not well understood in humans. We measured muscle BF within the thigh muscles of nine healthy young men using positron emission tomography during one-leg dynamic knee extension exercise in normoxia and moderate physiological systemic hypoxia (14% O(2) corresponding to approximately 3,400 m of altitude) without and with local adenosine receptor inhibition with femoral artery infusion of aminophylline. Systemic hypoxia reduced oxygen extraction of the limb but increased muscle BF, and this flow increment was confined solely to the exercising quadriceps femoris muscle. Exercising muscle BF heterogeneity was reduced from rest (P = 0.055) but was not affected by hypoxia. Adenosine receptor inhibition had no effect on capillary BF during exercise in either normoxia or hypoxia. Finally, one-leg exercise increased muscle BF heterogeneity both in the resting posterior hamstring part of the exercising leg and in the resting contralateral leg, whereas mean BF was unchanged. In conclusion, the results show that increased BF during one-leg exercise in moderate hypoxia is confined only to the contracting muscles, and the working muscle hyperemia appears not to be directly mediated by adenosine. Increased flow heterogeneity in noncontracting muscles likely reflects sympathetic nervous constraints to curtail BF increments in areas other than working skeletal muscles, but this effect is not potentiated in moderate systemic hypoxia during small muscle mass exercise.
AB - Although many effects of both acute and chronic hypoxia on the circulation are well characterized, the distribution and regulation of blood flow (BF) heterogeneity in skeletal muscle during systemic hypoxia is not well understood in humans. We measured muscle BF within the thigh muscles of nine healthy young men using positron emission tomography during one-leg dynamic knee extension exercise in normoxia and moderate physiological systemic hypoxia (14% O(2) corresponding to approximately 3,400 m of altitude) without and with local adenosine receptor inhibition with femoral artery infusion of aminophylline. Systemic hypoxia reduced oxygen extraction of the limb but increased muscle BF, and this flow increment was confined solely to the exercising quadriceps femoris muscle. Exercising muscle BF heterogeneity was reduced from rest (P = 0.055) but was not affected by hypoxia. Adenosine receptor inhibition had no effect on capillary BF during exercise in either normoxia or hypoxia. Finally, one-leg exercise increased muscle BF heterogeneity both in the resting posterior hamstring part of the exercising leg and in the resting contralateral leg, whereas mean BF was unchanged. In conclusion, the results show that increased BF during one-leg exercise in moderate hypoxia is confined only to the contracting muscles, and the working muscle hyperemia appears not to be directly mediated by adenosine. Increased flow heterogeneity in noncontracting muscles likely reflects sympathetic nervous constraints to curtail BF increments in areas other than working skeletal muscles, but this effect is not potentiated in moderate systemic hypoxia during small muscle mass exercise.
KW - Adenosine
KW - Adult
KW - Altitude
KW - Anoxia
KW - Capillaries
KW - Exercise
KW - Hemodynamics
KW - Humans
KW - Hyperemia
KW - Leg
KW - Male
KW - Muscle Contraction
KW - Muscle, Skeletal
KW - Oxygen
KW - Perfusion
KW - Quadriceps Muscle
KW - Receptors, Purinergic P1
KW - Rest
KW - Sympathetic Nervous System
U2 - 10.1152/ajpregu.00056.2010
DO - 10.1152/ajpregu.00056.2010
M3 - Journal article
C2 - 20427728
VL - 299
SP - R72-9
JO - American Journal of Physiology
JF - American Journal of Physiology
SN - 0363-6119
IS - 1
ER -
ID: 33815809