Table 2.

Metabolic and microvascular oxygenation responses at rest and during steady-state submaximal plantar flexion exercise in control and COPD subjects

	Controls	COPD
Baseline
Phosphorylated compounds and pH
PCr, mM	34 ± 5	36 ± 8
Pi, mM	1.9 ± 1.0	1.1 ± 0.4*
ADP, μM	8.2 ± 0.3	8.0 ± 0.7
pH	6.97 ± 0.02	6.96 ± 0.04
PDE, mM	2.0 ± 1.4	0.6 ± 0.6*
Microvascular oxygenation
Oxygenation index, %	62 ± 4	60 ± 7
Hb total, µM	55 ± 20	56 ± 27
HHb, µM	21 ± 8	23 ± 13
End exercise
Phosphorylated compounds and pH
PCr, mM	22 ± 6	21 ± 6
Pi, mM	10 ± 4	10 ± 4
ADP, μM	43 ± 21	47 ± 47
pH	6.99 ± 0.06	6.93 ± 0.09
Microvascular oxygenation
Oxygenation index, %	60 ± 4	55 ± 9
Hb total, µM	58 ± 22	58 ± 29
HHb, µM	24 ± 10	28 ± 20

Values are expressed as means ± SD. PCr, phosphocreatine; P_i, inorganic phosphate; PME, phosphomonoester; ADP, adenosine diphosphate; PDE, phosphodiester; Hb, total hemoglobin; HHb, deoxyhemoglobin.

^*P < 0.05, significantly different from controls.