Conventional Clearance Research Articles

Bilateral renal clearance. Technical problems and the effect of ureteric catheterization on renal function.

The difficulties of determining the function of each kidney with conventional clearance technique were studied in a series of 125 patients. The investigation, which consisted in determining the plasma clearance of inulin and para-aminohippuric acid (PAH), was begun with studying the total function by collecting the bladder urine. When this had been done, ureteric catheters were introduced to determine the function of each kidney.The examination was technically satisfactory in 60 of the 125 cases. In 34 cases minor leakage alongside the ureteric catheters precluded accurate determination of the function of each kidney. The values obtained were, therefore, minimum values of the renal function. However, in view of the slightness of the leakage, these studies were rated as acceptable from the practical clinical standpoint. In the remaining 31 cases the examination was technically unsatisfactory. The cause in eighteen instances was major leakage alongside the ureteric catheters or the catheters in the urethra,...

EFFECTS OF CHLORMERODRIN, P-CHLOROMERCURIBENZOATE AND DICHLORPHENAMIDE ON RENAL SODIUM REABSORPTION AND OXYGEN CONSUMPTION.

We administered an organic mercurial diuretic compound, an organic mercurial non-diuretic compound and an inhibitor of carbonic anhydrase to anesthetized dogs. Using conventional clearance methods, we

Interactions of neutral and acidic amino acids in renal tubular transport.

The effects of intravenous infusions of a variety of neutral and acidic amino acids on the plasma concentrations and excretions of naturally occurring amino acids were studied in dogs. Conventional clearance techniques were used, and the amino acid concentrations were determined by ion exchange column chromatography. Infusion of either l-glutamic acid or l-aspartic acid caused a gross increase in the plasma concentration and excretion of the other. Infusions of neutral amino acids including glycine, l-alanine, l-leucine, l-methionine, l-proline, and l-phenylalanine caused some minor changes in the endogenous plasma amino acid concentrations. They produced increases in the excretion of other neutral amino acids and, in some cases, of acidic and basic amino acids as well. In general, amino acids with long side chains were most effective in inhibiting reabsorption while cyclic side-chain compounds were less effective. There appear to be at least three somewhat separable mechanisms for renal tubular reabsorption of amino acids in dogs.

Renal activity of vasopressin in anesthetized dogs.

Conventional clearance techniques were used to study the renal response to vasopressin (5–100 mu/hr.) infused for 2 1/2 hours into anesthetized (pentobarbital), surgically traumatized dogs elaborating a dilute urine. Decreased urine flow, a concomitant sustained increase in Na+ excretion, increased urine osmolality, negative free-water clearance and an increased osmolal U/P ratio (>1, <2) consistently occurred during the infusion of 50 mu/hr. Urinary pH rose and HCO3–, rather than Cl–, was the predominant anion excreted. Tubular rejection of HCO3–, however, is not essential for vasopressin activity under the conditions of this investigation since antidiuresis occurred in an acidotic dog. Usually some increase in glomerular filtration rate and effective renal plasma flow were apparent during vasopressin infusion; the former change could account for the increased Na+ excretion, but it is difficult to ascribe the peculiar anion behavior to this factor. Maximum urinary concentration was not attained even with 100 mu vasopressin/hr.

Interactions of amino acids in renal tubular transport

The effects of intravenous infusions of l-lysine, l-arginine, l-histidine, l-ornithine and l-cysteine at three rates on the plasma levels and excretions of naturally occurring amino acids were studied in dogs. Conventional clearance techniques were used, and the amino acid concentrations in both plasma and urine were determined by column chromatography. A number of changes were observed in plasma amino acid concentrations, the most striking of which was a 20-fold increase in ornithine following arginine infusion. This increase is probably the result of conversion of arginine to ornithine via the Krebs-Henseleit cycle. Lysine, ornithine, arginine and cystine or cysteine showed marked mutual inhibition of tubular reabsorption. Histidine modestly inhibited reabsorption of these amino acids, and in turn its reabsorption was modestly depressed by them. The basic amino acid infusions also caused modest depression of the reabsorption of glycine and slight depression of that of several other amino acids. The reabsorptive mechanisms for lysine, arginine, ornithine and cystine are closely related and may be identical. There is, however, minor reabsorptive competition between these amino acids and certain others, suggesting that the mechanisms are not completely specific.

Renal blood flow in moderate hypothermia.

Although there is general agreement that renal blood flow is depressed by body cooling, there is some disagreement concerning the extent of this alteration. These discrepancies may be related to the wide variation in the degree of hypothermia induced1,6,7,10,11,15and, more particularly, to the methods for measuring renal blood flow.13Some evidence has been presented in the literature indicating that the conventional clearance techniques for measuring renal plasma and blood flow are not necessarily reliable in the hypothermic animal. Harsing and his associates6have pointed out that the clearance of para-aminohippurate may not be complete under hypothermic circumstances, possibly as a result of repression of secretory function of the tubules of the kidney. Balint and his colleagues2have recently pointed out that this may also be true when the extraction rate is simultaneously determined. Because of these discrepancies and the fact that we have been unable

Application of homeostatic principles to the management of nephrotic patients.

ATTENTION has been called to the fact that patients who have lost most of their normal capacity to eliminate water, potassium and phosphate as a consequence of severe renal damage may nonetheless retain a very satisfactory ability to take and eliminate considerable amounts of sodium and chloride.1 By contrast, as is well known, patients with childhood nephrosis may fail to eliminate dietary sodium chloride and water and may become markedly edematous despite the fact that their renal function, as judged by conventional clearance measurements and by their capacity to handle other ordinary dietary constituents such as potassium and phosphate, is . . .