Restricted postexercise pulmonary diffusion capacity and central blood volume depletion.

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Abstract
Hanel, Birgitte, Inge Teunissen, Alan Rabøl, Jørgen Warberg, and Niels H. Secher. Restricted postexercise pulmonary diffusion capacity and central blood volume depletion. J. Appl. Physiol. 83(1): 11–17, 1997.—Pulmonary diffusion capacity for carbon monoxide (Dl CO), regional electrical impedance (Z0), and the distribution of technetium-99m-labeled erythrocytes together with concentration of plasma atrial natriuretic peptide (ANP) were determined before and after a 6-min “all-out” row in nine oarsmen and in six control subjects. Two and one-half hours after exercise in the upright seated position, Dl CO was reduced by 6 (−2 to 21; median and range) %, the thoracic-to-thigh electrical impedance ratio (Z0 thorax/Z0 thigh) rose by 14 (−1 to 29) %, paralleled by a 7 (−3 to 11) % decrease and a 3 (−5 to 12) % increase in the thoracic and thigh blood volume, respectively. These responses were associated with a decrease in the plasma ANP concentration from 15 (13–31) to 12 (9–27) pmol/l ( P < 0.05). Similarly, in the supine position, Z0 thorax/Z0 thighincreased by 10 (−5 to 28) % when Dl CO was reduced 12 (6–26) % ( P < 0.05), whereas Dl COremained stable in the control group. The increase in Z0 thorax/Z0 thighand the corresponding redistribution of the blood volume in both body positions show that approximately one-half of the postexercise reduction of Dl CO is explained by a decrease in the pulmonary blood volume. The role of a reduced postexercise central blood volume is underscored by the lower plasma ANP, which aids in upregulating the blood volume after exercise in athletes.