TRANSCAPILLARY ESCAPE RATE OF ALBUMIN IN HUMANS DURING EXERCISE-INDUCED HYPERVOLEMIA

To test the hypotheses that plasma volume (PV) expansion 24 h after in tense exercise is associated with reduced transcapillary escape rate o f albumin (TERalb) and that local changes in transcapillary forces in the previously active tissues favor retention of protein in the vascul ar space, we measured PV, TERalb, plasma colloid osmotic pressure (COP p), interstitial fluid hydrostatic pressure (Pi), and colloid osmotic pressure in leg muscle and skin and capillary filtration coefficient ( CFC) in the arm and leg in seven men and women before and 24 h after i ntense upright cycle ergometer exercise. Exercise expanded PV by 6.4% at 24 h (43.9 +/- 0.8 to 46.8 +/- 1.2 ml/kg, P < 0.05) and decreased t otal protein concentration (6.5 +/- 0.1 to 6.3 +/- 0.1 g/dl, P < 0.05) and COPp (26.1 +/- 0.8 to 24.3 +/- 0.9 mmHg, P < 0.05), although plas ma albumin concentration was unchanged. TERalb tended to decline (8.4 +/- 0.5 to 6.5 +/- 0.7%/h, P = 0.11) and was correlated with the incre ase in PV (r = -0.69, P < 0.05). CFC increased in the leg (3.2 +/- 0.2 to 4.3 +/- 0.5 mu l.100 g(-1).min(-1).mmHg(-1), P < 0.05), and Pi sho wed a trend to increase in the leg muscle (2.8 +/- 0.7 to 3.8 +/- 0.3 mmHg, P = 0.08). These data demonstrate that TERalb is associated with PV regulation and that local transcapillary forces in the leg muscle may favor retention of albumin in the vascular space after exercise.