Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “AMINOHIPPURIC ACID”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 973 records · Page 54Linked to original sources
PubMed1980

pH gradient-stimulated transport of urate and p-aminohippurate in dog renal microvillus membrane vesicles.

The transport mechanism of urate and p-aminohippurate (PAH) was evaluated in microvillus membrane vesicles isolated from the renal cortex of the mongrel dog. Imposition of a transmembrane pH gradient (pHo less than pH1) markedly accelerated the uptake of [14C]urate and [3H]PAH and caused the transient accumulation ("overshoot") of each anion above its final level of uptake. The transport of urate and PAH under both stimulated (pHo less than pHi) and basal (pHo = pHi) conditions was insensitive to valinomycin-induced K+ diffusion potentials. The pH gradient-stimulated uptake of 25 microM [14C]urate and 1.0 microM [3H]PAH was significantly inhibited by 1.2 mM PAH, urate, furosemide, salicylate, or probenecid. The effect of each inhibitor on [14C]urate transport was identical to the effect of the same inhibitor on [3H]PAH flux. We conclude that the transport of urate and PAH in dog renal microvillus membrane vesicles occurs via a pH gradient-stimulated electroneutral carrier-mediated process such as 1:1 H+-anion cotransport or OH-anion exchange. Such a transport mechanism may possibly play a role in effecting uphill urate reabsorption in the proximal tubule. Moreover, this study demonstrates that secondary active solute transport in epithelial membranes may be coupled to the electrochemical gradient of an ion other than Na+.

Aminohippuric Acids↗
PubMed1990

Urate and p-aminohippurate transport in the brush border membrane of the pig kidney.

The transport of urate and p-aminohippurate (PAH) across the pig renal brush border membrane was investigated using membrane vesicles. Compared to a pH equilibrium condition (pHin = 7.4; pHout = 7.4), an outwardly directed OH- gradient (pHin = 7.4; pHout = 5.8) stimulated markedly both lactate and pyrazinoate uptake with overshoots exceeding 2 times that of the steady state. In contrast, neither OH-/urate nor OH-/PAH exchange could be demonstrated. An outwardly directed Cl- gradient (Cl-in = 100 mM; Cl-out = 16.7 mM) increased 2.6-fold 15-sec PAH uptake compared to Cl- equilibrium (Cl-in = Cl-out = 100 mM) but this stimulation was due solely to an effect of membrane potential. Creation of an electropositive intravesicular space, by imposing an inwardly directed K+ gradient (K+in = 0 mM; K+out = 100 mM) in the presence of valinomycin, was very effective to drive uphill PAH and urate accumulation compared to the control condition (no valinomycin). Four-second potential-stimulated PAH uptake was saturable (Km, 0.8 mM; Vmax, 1.7 nmol/mg of protein x 4 sec). Different organic anions cis-inhibited both 4-sec potential-stimulated PAH and urate uptakes in a similar fashion. PAH and urate, moreover, decreased each other's accumulation. In countertransport experiments, PAH and urate uptakes were not significantly stimulated by trans-unlabeled substrate. These results are consistent with the presence, in the pig renal brush border membrane, of a mediated secretory pathway common for urate and PAH, which could be facilitated by the potential difference existing in vivo across the luminal membrane of the proximal tubule.

Aminohippuric Acids↗
PubMed1986

Characteristics of renal p-aminohippurate and urate excretion in rabbits.

Urate and p-aminohippurate (PAH) excretion was studied in New Zealand white rabbits to determine the extent to which the renal tubular handling of these organic anions by intact kidneys paralleled observations made in single isolated perfused tubules in vitro. At low plasma concentrations (less than 60 mumol/L) net reabsorption of urate was observed in the majority of animals; as plasma urate concentration was increased by infusing lithium urate, net urate secretion was demonstrated, the fractional excretion of urate (FE urate) reaching 270%, and net urate secretion (filtered urate minus urinary concentration of urate times volume flow rate) 1.8 mumol/min at mean plasma urate levels 200 and 310 mumol/L. A maximal urate secretion rate was not demonstrated. Probenecid (250 mumol/kg) reduced FE urate to 27%, thereby revealing concealed reabsorption despite high plasma urate levels. By contrast, net secretion of PAH at all plasma levels was achieved by infusing NaPAH. The highest secretory rate was 38.6 mumol/min at plasma PAH levels between 1000 and 1750 mumol/L. Probenecid reduced fractional excretion of PAH (FEPAH) from 796% to 265%, no evidence of PAH reabsorption being found after inhibition of secretion with probenecid. At comparable plasma levels (220 mumol/L), net PAH secretion exceeded net urate secretion (reflected by the decrement in urate and PAH excretion caused by probenecid) by a factor of 5.3:1. These experiments indicate that urate and PAH are filtered and secreted by the rabbit kidney; however, only urate is significantly reabsorbed over the range of plasma organic anion levels examined. The configuration of the relation between plasma levels and net secretion rates and the greater secretory rate for PAH for urate in the living rabbit are consonant with the characteristics of PAH and urate transport determined previously in studies of isolated perfused proximal tubules.

Aminohippuric Acids↗
PubMed1984

Effects of p-aminohippurate and pyrazinoate on urate excretion in Cebus monkeys.

Changes in the fractional excretion of urate (FEurate) induced by various concentrations of p-aminohippurate (PAH) and pyrazinoate in plasma were evaluated in anesthetized Cebus monkeys using the standard clearance technique. PAH at concentrations between 2 and 40 micrograms/ml produced modest uricosuria (delta FEurate, ca 50%). At higher concentrations of PAH (up to 1200 micrograms/ml) the values of FEurate were not different from controls. Pyrazinoate at concentrations between 1 and 700 micrograms/ml reduced FEurate. The depressant effect of pyrazinoate was not influenced by the presence of PAH. These results are consistent with the idea that the secretory component for urate is distinct from that for PAH in this monkey.

Aminohippuric Acids↗
PubMed1983

Effects of pyrazinoate and p-aminohippurate on renal urate excretion by the dog and guinea pig.

In anesthetized dogs, pyrazinoate reduced the fractional excretion of urate when the concentration of the drug in plasma ranged from 3 to 300 micrograms/ml. At higher concentrations, fractional excretion rose progressively. p-Aminohippurate at concentrations in plasma ranging from 1 to 1000 micrograms/ml had no effect on the fractional excretion of urate. In guinea pigs, pyrazinoate exerted only a faint uricosuric action and p-aminohippurate was without effect. Both substances were tested over the range of 1 to 1000 micrograms/ml of plasma. The results in dogs help explain some previous reports of negative experiments with pyrazinoate; the doses used were not optimal for detecting responses. The results in guinea pigs suggested that urate secretion in this animal does not fit either of two previously recognized mechanisms.

Aminohippuric Acids↗
PubMed1977

pH-temperature dependence of organic acid transport in rat kidney slices.

Uptake of p-aminohippurate (PAH) by rat kidney slices was optimal at a pH of around 7.3 when incubation temperature was 37 degrees C. At 25 degrees C, however, optimal pH was increased to about 7.5. When the uptake was evaluated as a function of the OH/H ratio of the medium, it was found that optimal uptake is at a constant OH/H. Data showing the same characteristics of OH/H dependence were also observed for phenol red. Passive uptake of PAH was pH independent. Efflux rates for PAH also showed the pH optimal which was identical to that of uptake. At both 25 and 37 degrees C the Km appeared to be independent of pH while the maximum rate of active influx. An optimal OH/H ratio determines maximal velocity and this ratio is fixed and independent of temperature.

Aminohippuric Acids↗