Peter J. Talso

Depletion of Body Potassium by Diuretics

A study was designed to evaluate the [see table in the PDF file] [see table in the PDF file] hypothesis that the hypokalemia associated with the administration of thiazide diuretics reflects a redistribution of potassium rather than a depletion of body potassium. Exchangeable potassium, total body potassium, total body water, extracellular fluid volume, and serum sodium, potassium, chloride, bicarbonate, and pH of a group of hypertensive subjects were measured before and after 4 weeks of administration of dichlorphenamide and hydrochlorothiazide to these subjects. Significant decreases were observed in serum potassium (1.05 mEq/L), serum chloride (8.22 mEq/L), exchangeable potassium (21.1%), and total body potassium (16.7%) without a significant change in serum pH, sodium, and bicarbonate. Body weight, total body water, and extracellular fluid volume also decreased, but the change in body weight was not sufficient to explain the potassium deficit produced. The mechanisms responsible for the loss of potass...

A study of nonmyelinated nerves in the rat and rabbit heart

Submicroscopic studies of the papillary muscle and ventricular myocardium of the rat and rabbit have revealed: (1) a dearth of nervous elements—an observation which contradicts the comparatively rich innervation suggested by investigators studying silver-stained preparations by light microscopic techniques; (2) the presence of nonmyelinated nerve fibers only; and (3) the apparent termination of nonmyelinated fibers at a significant distance from the myocardial cells.

Kinetic analysis of isotope exchange from a cylinder

Abstract Isotopic exchange phenomena between a sample confined in a cylindrical container and a completely mixed solution of infinite size was analyzed. Ficks second law was used for the analysis of the transport of the labeled species from the cylindrical cell to the external solution. The model chosen for the analysis was that of two composite cylinders with different diffusion coefficients. Two cases were analyzed, where no mixing existed, and where complete mixing of the sample took place during the isotopic exchange. The analysis shows that the ratios of the diffusion coefficients and the thickness of the solution and membrane contribute to the number of observable exponential terms when the isotope remaining in the cylinder is plotted against time.

Kinetic analysis of isotope exchange from a cylinder containing dissociable non-permeable interacting substance

Abstract A kinetic analysis was determined of an isotopic exchange between a cylinder containing non permeable interacting substance and an infinitely large sink. Ficks second law of diffusion coupled with reversible first-order reaction was used for the analysis. The analysis was made in two conditions, one without mixing and the other with complete mixing of the sample in the cylinder. The equations expressing the amount of radioisotope remaining in the cylinder were derived as a function of time. These show that the appearance of the multi-exponential curves occur whenever the chemical reaction rate constant is close to or smaller than the diffusion constant. If the reaction rate constant is very large, the overall rate of decrease in the isotope in the cylinder is expressed as straight diffusion from a cylinder. The observable “rate constant” in the latter case is a function of the ratio of isotope between “free” and “bound” phases. The equation can be used experimentally to determine the ratio of the isotope in the “bound” and “free” phases of the sample if the membrane is a truly rate-determining step of the isotopic exchange.

Effects of Diuretic Agents on Serum and Tissue Electrolytes in Rats.

Summary and Conclusions Hydrochloro thiazide, polythiazide and chlorthalidone were added to the diets of 3 groups of Sprague-Dawley rats. After 4 weeks of subsistence on this diet, these animals together with matched controls were sacrificed and analyses of serum and tissue electrolytes were done. The serum chloride concentration was significantly lower in each experimental group. Serum potassium concentration was decreased in all 3 groups, and was significantly lowered in the groups receiving chlorthalidone and hydrochlorthiazide. Changes in serum sodium concentration were not statistically significant. Tissue analyses revealed no significant alterations in water or electrolyte content. These studies suggest that the hypokalemia associated with oral diuretic therapy results from a redistribution of potassium stores rather than a frank depletion of this ion in rats.