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Pulmonary capillary blood volume and diffusing membrane capacity during exercise in humans: role of pulmonary artery pressure
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DOI：10.1152/ajplung.00358.2024.png)
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Abstract
En 中文
During exercise, lung diffusing capacity for carbon monoxide (DLCO), pulmonary capillary blood volume (Vc), and diffusing membrane capacity (DM) increase secondary to a rise in pulmonary artery pressure (PAP) and central blood volume mobilization. Although the role of central blood volume on DLCO is well established, the impact of PAP on DLCO, Vc, and DM during exercise is less clear. Based on previous work, we tested the hypothesis that acute increases in PAP will potentiate exercise DLCO via increases in DM. Fifteen healthy young adults (7 females; age: 24 +/- 4 yr) completed two bouts of cycling exercise at 60 W, with (CUFF) or without (CON) bilateral thigh cuff inflation pressurized to 90 mmHg. The multiple fractions of the inspired O2-DLCO method were used to determine DLCO, Vc, and DM at baseline and during both exercise conditions alongside estimates of cardiac output (Qc; impedance cardiography) and right ventricular systolic pressure (RVSP; echocardiography). CUFF exercise resulted in a larger increase in RVSP (CUFF: 44.7 +/- 6.1 vs. CON: 38.9 +/- 5.5 mmHg; P = 0.036) but not Qc (P = 0.644) or Vo2 (P = 0.976) compared with CON. DLCO was higher during the CUFF exercise (CUFF: 41 +/- 6 vs. CON: 38 +/- 6 mL/min/mmHg; P = 0.001) and was mediated by increases in DM (CUFF: 138 +/- 55 vs. CON: 90 +/- 39 mL/min/mmHg; P = 0.032), not Vc (CUFF: 85 +/- 18 vs. CON: 98 +/- 27 mL/min/mmHg; P = 0.820). Increases in RVSP were positively related to DM (rrm = 0.82; P = 0.024) but inversely related to Vc (rrm = -0.80, P = 0.029). Collectively, these data indicate that PAP primarily contributes to DLCO during low-intensity exercise via increases in capillary recruitment (i.e., DM). NEW & NOTEWORTHY Pulmonary artery pressure contributes to DLCO recruitment during exercise. However, it is unclear how pulmonary artery pressure impacts the pulmonary microcirculatory adjustments that comprise DLCO, namely Vc and DM. Using subsystolic occlusion of the locomotor muscles during exercise to induce increases in pulmonary artery pressure, without changes in cardiac output or metabolic demand, we demonstrate that pulmonary artery pressure contributes to DLCO during exercise via heightened capillary recruitment (DM).
Keywords:
gas exchange
lung diffusing capacity
multiple FIo(2)
sympathetic nervous system
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