Effect of Acidosis and Alkalosis on Excretion of Water and Solutes During Periods of Hydropenia and of Overhydration in Dogs

Abstract

Dogs, under conditions of standard hydropenia, overhydratton, and experimental diabetes insipidus (D.I.), were rendered acidotic by infusions of sodium dihydrogen phosphate, and alkalotic by infusions of sodium bicarbonate. After NaH2PO4, serum pH and CO2 content fell to values of 6.7 and 6.4 m[image]/1, respectively. After NaHCO3, serum pH and CO2 content reached values of 7.93 and 78.4 m[image]/1. These changes had but little effect on mean values of creatinine clearance, 91.1 and 86.3 cc/min/m2 during acidosis and alkalosis, respectively. The urine flow, during hydropenia, and after loading with both the acidic and basic salt, was dependent solely on the number of osmotically active solutes in the final urine, and not on the degree of acidity or alkalinity of serum or urine. Over-hydrated or DI dogs, prior to loading, excreted urine at high rates of flow (0.9-1.9cc/minute), and low osmolarities (100-200 mOs/1). During loading, with increasing flow, osmotic activity of urine reached values of 250-350 mOs/1, falling significantly below the usual hydropenic range of osmolarity. Thus, the hydrated or DI dog elaborated 1.5-3 times the minimal or hydropenic volume of urine for excretion of a given solute load. With respect to the chemical anatomy of urine after loading with a given solute, the following facts were found: a) percentage distribution of individual urinary solutes, was predominantly a function of the "particulate" solute load of the final urine. b) Percentage distribution of 90-95% of urine solutes was independent of the state of hydration of the animal. Under the experimental conditions outlined herein, tubular activities of acid-base transfers on the one hand, were independent of those of tubular water exchange on the other.