Moment analysis of drug disposition in kidney. III: Transport of p-aminohippurate and tetraethylammonium in the perfused kidney isolated from uranyl nitrate-induced acute renal failure rats.

A different manner of insufficiency of renal epithelial cell transport between the organic anion and cation, p-aminohippurate and tetraethylammonium, respectively, was observed in the perfused kidney isolated from uranyl nitrate-induced acute renal failure (ARF) rats. The single-pass outflow pattern of the perfused kidney was analyzed by noncompartmental moment analysis. The active tubular secretion was impaired faster than the reduction of glomerular filtration, and the tetraethylammonium secretion decreased at an earlier stage of ARF than p-aminohippurate. The apparent uptake rate constant from blood to cells of p-aminohippurate was reduced with the progress of ARF and associated with the amount of this drug secreted, whereas the uptake rate constant of tetraethylammonium did not change until the late stage of ARF. The mean residence time in renal epithelial cells of tetraethylammonium was prolonged with reduction of the amount to be secreted, while that of p-aminohippurate remained unchanged. Therefore, the uptake of p-aminohippurate across the basolateral membranes decreased gradually, and the transport across the brush border membranes was still unchanged after uranyl nitrate treatment. On the other hand, the secretion of tetraethylammonium from cells to lumen was impaired at first, and then the uptake from blood to cells was impaired. These results suggest that impairment by uranyl nitrate-induced ARF appears at the carrier-mediated transport process of the epithelial cell membranes for both organic anions and cations.

Renal handling of drugs in renal failure. I: Differential effects of uranyl nitrate- and glycerol-induced acute renal failure on renal excretion of TEAB and PAH in rats.

Two etiologically different models of experimental acute renal failure were induced in rats by administration of either glycerol or uranyl nitrate. Both compounds caused a substantial decrease in the glomerular filtration rate (GFR) and the net tubular secretion of tetraethylammonium bromide (TEAB) and para-aminohippuric acid (PAH). The degree of renal impairment induced by uranyl nitrate and glycerol appeared to be dose related. Deprivation of drinking water 24 hr before the administration of glycerol potentiated the renal damage. In uranyl nitrate-induced renal failure, the decline of the net tubular secretion for TEAB and PAH was not proportional to the decrease in GFR; the secretion process deteriorated faster than the GFR. For example, when 0.5 mg/kg uranyl nitrate was administered, GFR fell to approximately 65% of normal, whereas the net tubular secretion was decreased to 30% of normal. These results suggest that the tubular transport was preferentially affected by uranyl nitrate. In contrast, in glycerol-induced renal failure, the decline of TEAB secretion fell in a parallel fashion with the GFR, suggesting that the glomeruli and the proximal tubules were equally damaged by glycerol. However, in this latter model, the decline of PAH secretion did not parallel the decrease in GFR, contradicting the proposal that glycerol affects equally the glomeruli and the proximal tubules. This discrepancy may be due to the selective competitive inhibition of PAH secretion by the accumulation of naturally occurring organic acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Simultaneous determination of p-aminobenzoic acid, acetyl-p-aminobenzoic acid and p-aminohippuric acid in serum and urine by capillary gas chromatography with use of a nitrogen-phosphorus detector.

In various studies during recent years, the use of p-aminobenzoic acid has been described in screening tests for exocrine pancreatic function. A synthetic three-unit compound N-benzoyl-L-tyrosyl-p-aminobenzoic acid has been administered orally and hydrolysed in the small intestine in the presence of chymotrypsin to N-benzoyl-L-tyrosine and p-aminobenzoic acid. This study describes a convenient procedure in which, after a selective extraction and derivatization with diazomethane, capillary gas chromatography is used combined with nitrogen-sensitive detection. With the proposed procedure, p-aminobenzoic acid and its major metabolites, acetyl-p-aminobenzoic acid and p-aminohippuric acid, can be monitored in serum and in urine samples.

Effect of substrate pretreatment on renal organic ion transport in the adult rat.

The ability of renal cortical slices to accumulate PAH and NMN was not significantly affected by pretreatment of adult rats with large doses of PAH. Pretreatment of adult rats with THAM significantly increased PAH accumulation but had no effect on NMN. Inulin and PAH clearance and filtration fraction were significantly decreased by PAH pretreatment but unaffected by THAM pretreatment. The effects of pretreatment on transport are probably due to non-specific toxicity.

Micropuncture studies of glucose transport in the dog: mechanism of renal glycosuria.

Clearance and micropuncture studies were performed in 23 dogs without glucose loading to examine the tubule mechanism of renal glycosuria. Studies were carried out in three groups of animals before and after 10% extracellular volume expansion, and administration of maleic acid in low dose at 150 mumol/kg and in high dose at 300 mumol/kg. Specific hexokinase methods were used for the determination of glucose in tubule fluid and urine. Under control conditios, glucose reabsorption occurred predominantly in the proximal tubule. In all three groups, proximal tubule reabsorption of both sodium and glucose was inhibited in the second phase, showing a good correlation between the two. In contrast, fractional urinary glucose excretion remained unchanged after volume expansion and low-dose maleic acid, indicating reabsorption of virtually all the increased glucose load at a further "distal" site. On the other hand, significant glycosuria developed after high-dose maleic acid that was a result of reduced glucose reabsorption in the distal nephron, in addition to the proximal effect. It was concluded that distal glucose transport plays a significant role in regulating urinary glucose excretion and maintains renal thershold for glucose,

[Influence of intravenous steroid administration on kidney function]. / Beeinflussung der Nierenfunktion durch intravenöse Steroid-Gaben

The acute renal response to 1,0 g Prednisolon i.v. in kidney transplant recipients and normal controls was investigated. The results indicate an acute suppression of glomerular filtration rate (CIN, CCR) and effective plasma flow (CPAH). The reabsorption of sodium in the proximal tubule was shown to be impaired as a direct effect of the steroid infusion, as well as there was an increase in the filtered fraction of potassium. The creatinine clearance under treatment of high doses of steroids does not reflect the actual changes in glomerular filtration rate

Occupational lead nephropathy.

Among eight subjects suspected of excessive occupational exposure to lead, detailed examination of renal function identified abnormalities in four. Glomerular filtration rate was less than 87 ml/mim/1.73 m2 in one subject with asymptomatic renal failure, and in three subjects with preclinical renal dysfunction. In the subject with asymptomatic renal failure, chelation therapy increased the glomerular filtration rate, p-aminohippurate (PAH) extraction, the maximal PAH secretion rate (TmPAH) and improved proximal tubule ultrastructure, despite decreased renal plasma flow. This improvement in PAH transport was associated with correction of a proximal tubule defect in tritiated PAH uptake detected by section freeze-dry autoradiography of renal biopsy specimens. In three subjects, the etiologic diagnosis of lead-induced nephropathy was established by exclusion, but tubular dysfunction did not obviously exceed the reduction in blomerular filtration. Proximal tubule abnormalities were seen in each of the three patients who underwent biopsy. These studies suggest that lead nephropathy may be an important occupational hazard in the United States lead industry.

Radiology of the urinary tract: some physiological considerations. Annual oration in memory of John S. Bouslog, M.D., 1890-1973.

This paper reviews some of the fundamental technical and diagnostic problems in clinical uroradiology, such as (a) the reason for the obstructive nephrogram; (b) why high-dose urography gives better studies than low-dose; (c) why the Trueta phenomenon has not been demonstrated in man; (d) the case for an intrarenal arterial collateral pathway via the pericalyceal network (these vessels can be demonstrated in man and must not be misinterpreted as tumor vessels or vascular malformations). One of the most baffling problems sometimes occurs with the sudden partial block of a single segmental vessel: the kidney ceases to excrete urine and eventually becomes atrophic even though some excretory function returns. To date, there is no satisfactory explanation for this course of events.

Origins of the uricosuric response.

The acute effects of intravenous (i.v.) probenecid and chlorothiazide on renal urate handling were investigated in paired studies in normal men. Uricosuric responses to these agents were compared in the same subjects, both without and with pyrazinamide (PZA) pretreatment. Assuming that PZA selectively inhibits the tubular secretion of urate and that uricosuric agents act by increasing the excretion of filtered urate, then the uricosuric responses (the increment in urate excretion or clearance) should have been unaffected by PZA. Defined in this manner, however, uricosuric responses to probenecid and chlorothiazide were significantly decreased after PZA pretreatment. In order to determine whether PZA diminished other renal actions of chlorothiazide, changes in sodium and inorganic phosphorus excretion were examined. Chlorothiazide produced equivalent natriuretic and phosphaturic responses after PZA pretreatment, indicating that PZA does not interfere with at least some of the renal actions of chlorothiazide. In separate studies, PZA depressed urate excretion by at least 68% during the maintenance of chlorothiazide-induced natriuresis and phosphaturia, suggesting that chlorothiazide does not diminish the anti-secretory action of PZA. The results suggest that probenecid and chlorothiazide may derive their uricosuric properties by facilitating the excretion of both filtered and secreted urate. Possibly, increased excretion of secreted urate might occur through modulation of urate reabsorption at a site distal to tubular secretion, rather than by the direct acceleration of secretory transport. However, PZA-induced interference with the actions of probenecid and chlorothiazide on renal urate transport mechanisms cannot be excluded as a possible explanation for the present results.