Intramembranous solute and water fluxes during high intramembranous absorption rates in fetal sheep with and without lung liquid diversion

Under basal conditions, passive diffusion makes a minor and bulk flow a major contribution to intramembranous solute absorption. During high absorption rates, the increase in solute absorption above basal levels appears to be due entirely to bulk flow and is unaffected by lung liquid. The increased bulk flow is consistent with vesicular transcytosis.