RESTRICTED POSTEXERCISE PULMONARY DIFFUSION CAPACITY DOES NOT IMPAIR MAXIMAL TRANSPORT FOR O-2

We evaluated whether the postexercise reduction of pulmonary diffusion capacity for carbon monoxide (DL(CO)) is influenced by a second bout of rowing and whether it affects arterial O-2 tension during maximal exercise. After exercise, DL(CO) was reduced [from a median of 37 (range of 30-44) to 34 (27-40) ml.min(-1).mmHg(-1); n = 21; P < 0.001], and both the membrane diffusion capacity [from 80 (58-139) to 68 (54-104) ml.min(-1).mmHg(-1)] and the pulmonary capillary blood volume [from 88 (74-119) to 79 (61-121) ml; P < 0.01] were affected. A second bout of exercise did not influence DL(CO) or membrane diffusion capacity (n = 7), but during both bouts arterial O-2 tension was reduced [from 105 (91-110) to 91 (77-102) Torr; P < 0.001] and arterial O-2 saturation decreased [from 0.98 (0.97-0.99) to 0.95 (0.86-0.96); P < 0.001]. Furosemide (iv) did not affect DL(CO) (n = 7), suggesting that it was influenced by the central blood volume rather than by pulmonary edema.