Abstract
The rate of outward capillary filtration induced by water drinking was measured by means of the pressure plethysmography in the calf of two healthy young men. The maximum rate of filtration was 0.026 and 0.024ml/min/100ml calf after drinking water of 1% of body weight. Ingestion of 0.9% saline, however, caused no such fluid movement. Capillary filtration coefficient (CFC) of calf, estimated at the same time, was 0.0030 and 0.0033ml/min/100ml calf/ mmHg. From these data, the maximum increase in effective filtration pressure after water drinking was estimated to be 8.7 and 7.3mmHg. No change in calf blood flow and CFC was observed of ter water drinking. The decrease in plasma protein. concentration was 0.4g/100ml, corresponding to 2.2mmHg fall of plasma colloid osmotic pressure. The plasma osmolality was decreased by 4 and 6mOsm/KgH2O of ter water drinking, but remained unchanged of ter saline drinking. It was concluded that a decrease in crystalloid osmotic pressure caused the observed fluid movement.
