Production of Increased Renal Sodium Excretion by the Hypotonic Expansion of Extracellular Fluid Volume in Recumbent Subjects 1

Response of Normal Subjects to Large Amounts of Aldosterone1

“…The return to sodium and water balance occurs more quickly than seen in this study because maximal or near maximal fluid retention is already present and the stage is set for sodium excretion. Evidence in favor of this concept is found in the natriuresis following acute expansion of body fluids with saline in prehydrated subjects (39,40), patients with Cushing's syndrome (41,42), and subjects pretreated with ACTH or corticosteroids (43,44). Expansion of extracellular fluid volume with intravenous saline or Pitressin® and water will lead to diminished aldosterone and increased sodium excretion (11)(12)(13)45); that sodium excretion results from diminished aldosterone has been suggested (11)(12)(13).…”

Diurnal Variation in the Diuretic Response to Ingested Water

“…These observations may indicate that under conditions when salt is plentiful, expansion of the volume of body water in the morning is an effective stimulus for significantly increased sodium excretion. It has been demonstrated that the natriuretic response of the kidney to hypotonic expansion of extracellular fluid volume is modified by the posture of the subject (31). It is possible that this response to increased volume is also influenced by the time of day at which the expansion occurs.…”

The Effect of an Arteriovenous Fistula on Renal Hemodynamics and Electrolyte Excretion 1

“…Studies of the effects of posture on diuresis support the view that the effective distribution of blood rather than its total volume is important in influencing renal behavior (6,40,41). The great veins (42), the right heart and pulmonary artery (43), the cranial cavity (44), the "cephalad portion of the body" (45), and the arterial pressoreceptors (46) (50,51), and hemorrhage (52,53) are associated with a diminution in total blood volume. In quiet standing (6), venous congestion of the limbs (54,55), partial occlusion of the superior or inferior vena cava (56), and portal hypertension (57), filtration from the capillaries is increased and in addition blood is pooled in the peripheral veins, away from the general circulation.…”