Pulmonary capillary surface area in supine exercising humans: demonstration of vascular recruitment.

Pulmonary capillary surface area in supine exercising humans: demonstration of vascular recruitment.
Am J Physiol Lung Cell Mol Physiol. 2019 Jun 26;:
Authors: Langleben D, Orfanos SE, Giovinazzo M, Schlesinger RD, Naeije R, Fox BD, Abualsaud AO, Blenkhorn F, Rudski LG, Catravas JD
Abstract
In exercising humans, cardiac output (CO) increases, with minor increases in pulmonary artery pressure (PAP). It is unknown if the CO is accommodated via distention of already perfused capillaries or via recruitment of non-concomitantly perfused pulmonary capillaries. Ten subjects (9 female) performed symptom-limited exercise. Six had resting mean PAP (PAPm) < 20 mm Hg and four had PAPm between 21 and 24 mm Hg. The first-pass pulmonary circulatory metabolism of 3H-benzoyl-Phe-Ala-Pro (BPAP) was measured at rest and at peak exercise, and functional capillary surface area (FCSA) was calculated. Data are mean±SD. Mean pulmonary arterial pressure rose from 18.8±3.3 SD mm Hg to 28.5±4.6, CO from 6.4±1.6 L/min to 13.4±2.9, and pulmonary artery wedge pressure from 14±3.3 mm Hg to 19.5±5 (all p ≤ 0.001). Percent BPAP metabolism fell from 74.7%±0.1 to 67.1±0.1, and FCSA/body surface area (FCSA/BSA) rose from 2939±640 mL/min/m2 to 5018±1032 (all p < 0.001). In nine subjects, the FCSA/BSA to CO relationship suggested principally capillary recruitment and not distention. In subject 10, a marathon runner, resting CO and FCSA/BSA were high, a...

Source: Am J Physiol Lung Ce... - June 25, 2019 Category: Respiratory Medicine Authors: Langleben D, Orfanos SE, Giovinazzo M, Schlesinger RD, Naeije R, Fox BD, Abualsaud AO, Blenkhorn F, Rudski LG, Catravas JD Tags: Am J Physiol Lung Cell Mol Physiol Source Type: research