Kinetics of skeletal muscle O2 delivery and utilization at the onset of heavy-intensity exercise in pulmonary arterial hypertension.

Autor:	Barbosa, Priscila B., Ferreira, Eloara M. V., Arakaki, Jaquelina S. O., Takara, Luciana S., Moura, Juliana, Nascimento, Rúbia B., Nery, Luiz E., Neder, J. Alberto, Nascimento, Rúbia B
Předmět:	PULMONARY artery diseases PORTAL hypertension CONNECTIVE tissue diseases OXYHEMOGLOBIN AEROBIC metabolism OXYGEN metabolism COMPARATIVE studies DYNAMICS EXERCISE EXERCISE tests RESEARCH methodology MEDICAL cooperation OXYGEN PULMONARY gas exchange PULMONARY hypertension RESEARCH EVALUATION research OXYGEN consumption SKELETAL muscle
Zdroj:	European Journal of Applied Physiology; Jul2011, Vol. 111 Issue 8, p1851-1861, 11p, 2 Charts, 2 Graphs
Abstrakt:	Impaired O(2) delivery relative to O(2) demands at the onset of exercise might influence the response profile of muscle fractional O(2) extraction (≅Δ[deoxy-Hb/Mb] by near-infrared spectroscopy) either by accelerating its rate of increase or creating an "overshoot" (OS) in patients with pulmonary arterial hypertension (PAH). We therefore assessed the kinetics of O(2) uptake [Formula: see text] Δ[deoxy-Hb/Mb] in the vastus lateralis, and heart rate (HR) at the onset of heavy-intensity exercise in 14 females with PAH (connective tissue disease, IPAH, portal hypertension, and acquired immunodeficiency syndrome) and 11 age- and gender-matched controls. Patients had slower [Formula: see text] and HR dynamics than controls (τ[Formula: see text] = 62.7 ± 15.2 s vs. 41.0 ± 13.8 s and t (1/2)-HR = 61.3 ± 16.6 s vs. 43.4 ± 8.8 s, respectively; p < 0.01). No study participant had a significant reduction in oxyhemoglobin saturation. In OS(-) subjects (6 patients and 7 controls), the kinetics of Δ[deoxy-Hb/Mb] relative to [Formula: see text] were faster in patients (p = 0.05). Larger area under the OS and slower kinetics (MRT) of the "downward" component indicated greater O(2) delivery-to-utilization mismatch in OS(+) patients versus OS(+) controls (477.4 ± 330.0 vs. 78.1 ± 65.6 a.u. and 74.6 ± 18.8 vs. 46.0 ± 17.0 s, respectively; p < 0.05). Resting pulmonary vascular resistance was higher in OS(+) than OS(-) patients (23.1 ± 12.0 vs. 10.7 ± 4.0 Woods, respectively; p < 0.05). We conclude that microvascular O(2) delivery-to-utilization inequalities slowed the rate of adaptation of aerobic metabolism at the start of heavy-intensity exercise in women with PAH. [ABSTRACT FROM AUTHOR]
Databáze:	Complementary Index
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