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Effect of t-butylhydroperoxide on p-aminohippurat uptake in rabbit renal cortical slices.

Choi SS, Huh KD, Woo JS, Kim YK - Korean J. Intern. Med. (1994)

Bottom Line: The efflux rate constant pf PAH was not altered by the presence of 1 mM t-BHP, indicating that the inhibitory effect of t-BHP on the steady-state accumulation of PAH is due primary to the reduction in the influx of PAH across the basolateral membrane.The kinetic analysis showed that 1mM t-BHP caused a significant reduction in the maximum rate of PAH influx(Vmax) from 1.54 +/- 0.74 to 0.72 +/- 0.54 umol/g/10 min without an effect on Km, indicating that t-BHP depressed PAH influx across the basolateral membrane by reducing the number or turnover rate of active carrier for PAH transport, but not by altering substrate affinity of the carrier.These results suggest that t-BHP inhibition of PAH uptake is attributed to renal tubular cell damage and lipid peroxidation plays an important role in the inhibitory effect of t-BHP on PAH transport in rabbit proximl tubules.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal Medicine, St. Benedict Hospital, Pusan, Korea.

ABSTRACT

Objectives: Oxygen free radical (superoxide radical, hydrogen peroxide, and hydroxyl radicals) have been considered to be responsible for the pathogenesis of ischemia reperfusion injury and toxic chemical injury in a variety of organs including myocardium, brain, intestine and kidneys. In in vitro models using a suspension of rat proximal tubule segments, t-butylhydroperoxide(t-BHP), a potent oxidant, induces the severity of tubular dysfunction as reflected by decreases in tubular respiration which is associated with a progressive increase in lipid peroxidation. The precise mechanism of t-BHP-induced cell injury remains to be determine. The study was carried out to determine the effect of oxygen free radicals on organic anion transport in renal proximal tubule.

Methods: By renal cortical slices, we studied accumulation of organic ions, PAH efflux oxygen consumption, lactate dehydrogenase (LDH), lipid peroxidation. The data are expressed as the mean +/- SE and evaluated for significance using Student's t-test. A probability level of 0.05 was used to establish significance.

Results: Effect of t-butylhydroperioxide(t-BHP), a potent oxidant, on organic anion p-amminohippurate(PAH) uptake was studied in rabbit renal cortical slices. t-BHP inhibited irreversibly PAH and organic cation tetraethylammonium(TEA) uptake in a dose dependent manner with IC50 of approximately 1.0 and 0.85 mM, respectively. The efflux rate constant pf PAH was not altered by the presence of 1 mM t-BHP, indicating that the inhibitory effect of t-BHP on the steady-state accumulation of PAH is due primary to the reduction in the influx of PAH across the basolateral membrane. The kinetic analysis showed that 1mM t-BHP caused a significant reduction in the maximum rate of PAH influx(Vmax) from 1.54 +/- 0.74 to 0.72 +/- 0.54 umol/g/10 min without an effect on Km, indicating that t-BHP depressed PAH influx across the basolateral membrane by reducing the number or turnover rate of active carrier for PAH transport, but not by altering substrate affinity of the carrier. Ouabain-sensitive and -insensitive oxygen consumption was not different between the control and t-BHP-treated slices. t-BHP caused an increase in LDH release and lipid peroxidation in a dose-dependent manner, which were highly correlated with changes in PAH uptake.

Conclusion: These results suggest that t-BHP inhibition of PAH uptake is attributed to renal tubular cell damage and lipid peroxidation plays an important role in the inhibitory effect of t-BHP on PAH transport in rabbit proximl tubules.

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Inhibitory effect of various concentrations of t-BHP on PAH and TEA uptake in rabbit renal cortical slices. Each point represents the mean±SE of four experiments. **p < 0.01 compared to the control value.
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f1-kjim-9-2-105-9: Inhibitory effect of various concentrations of t-BHP on PAH and TEA uptake in rabbit renal cortical slices. Each point represents the mean±SE of four experiments. **p < 0.01 compared to the control value.

Mentions: PAH and TEA uptake in cortical slices was measured in the presence of various concentrations of t-BHP in the incubation medium. The results are depicted in Fig. 1. t-BHP inhibited PAH and TEA uptake in a dose-dependent manner over the concentrations of 0.5–2.0mM, showing 50% inhibition at 1.0 and 0.85mM, respectively.


Effect of t-butylhydroperoxide on p-aminohippurat uptake in rabbit renal cortical slices.

Choi SS, Huh KD, Woo JS, Kim YK - Korean J. Intern. Med. (1994)

Inhibitory effect of various concentrations of t-BHP on PAH and TEA uptake in rabbit renal cortical slices. Each point represents the mean±SE of four experiments. **p < 0.01 compared to the control value.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4532070&req=5

f1-kjim-9-2-105-9: Inhibitory effect of various concentrations of t-BHP on PAH and TEA uptake in rabbit renal cortical slices. Each point represents the mean±SE of four experiments. **p < 0.01 compared to the control value.
Mentions: PAH and TEA uptake in cortical slices was measured in the presence of various concentrations of t-BHP in the incubation medium. The results are depicted in Fig. 1. t-BHP inhibited PAH and TEA uptake in a dose-dependent manner over the concentrations of 0.5–2.0mM, showing 50% inhibition at 1.0 and 0.85mM, respectively.

Bottom Line: The efflux rate constant pf PAH was not altered by the presence of 1 mM t-BHP, indicating that the inhibitory effect of t-BHP on the steady-state accumulation of PAH is due primary to the reduction in the influx of PAH across the basolateral membrane.The kinetic analysis showed that 1mM t-BHP caused a significant reduction in the maximum rate of PAH influx(Vmax) from 1.54 +/- 0.74 to 0.72 +/- 0.54 umol/g/10 min without an effect on Km, indicating that t-BHP depressed PAH influx across the basolateral membrane by reducing the number or turnover rate of active carrier for PAH transport, but not by altering substrate affinity of the carrier.These results suggest that t-BHP inhibition of PAH uptake is attributed to renal tubular cell damage and lipid peroxidation plays an important role in the inhibitory effect of t-BHP on PAH transport in rabbit proximl tubules.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal Medicine, St. Benedict Hospital, Pusan, Korea.

ABSTRACT

Objectives: Oxygen free radical (superoxide radical, hydrogen peroxide, and hydroxyl radicals) have been considered to be responsible for the pathogenesis of ischemia reperfusion injury and toxic chemical injury in a variety of organs including myocardium, brain, intestine and kidneys. In in vitro models using a suspension of rat proximal tubule segments, t-butylhydroperoxide(t-BHP), a potent oxidant, induces the severity of tubular dysfunction as reflected by decreases in tubular respiration which is associated with a progressive increase in lipid peroxidation. The precise mechanism of t-BHP-induced cell injury remains to be determine. The study was carried out to determine the effect of oxygen free radicals on organic anion transport in renal proximal tubule.

Methods: By renal cortical slices, we studied accumulation of organic ions, PAH efflux oxygen consumption, lactate dehydrogenase (LDH), lipid peroxidation. The data are expressed as the mean +/- SE and evaluated for significance using Student's t-test. A probability level of 0.05 was used to establish significance.

Results: Effect of t-butylhydroperioxide(t-BHP), a potent oxidant, on organic anion p-amminohippurate(PAH) uptake was studied in rabbit renal cortical slices. t-BHP inhibited irreversibly PAH and organic cation tetraethylammonium(TEA) uptake in a dose dependent manner with IC50 of approximately 1.0 and 0.85 mM, respectively. The efflux rate constant pf PAH was not altered by the presence of 1 mM t-BHP, indicating that the inhibitory effect of t-BHP on the steady-state accumulation of PAH is due primary to the reduction in the influx of PAH across the basolateral membrane. The kinetic analysis showed that 1mM t-BHP caused a significant reduction in the maximum rate of PAH influx(Vmax) from 1.54 +/- 0.74 to 0.72 +/- 0.54 umol/g/10 min without an effect on Km, indicating that t-BHP depressed PAH influx across the basolateral membrane by reducing the number or turnover rate of active carrier for PAH transport, but not by altering substrate affinity of the carrier. Ouabain-sensitive and -insensitive oxygen consumption was not different between the control and t-BHP-treated slices. t-BHP caused an increase in LDH release and lipid peroxidation in a dose-dependent manner, which were highly correlated with changes in PAH uptake.

Conclusion: These results suggest that t-BHP inhibition of PAH uptake is attributed to renal tubular cell damage and lipid peroxidation plays an important role in the inhibitory effect of t-BHP on PAH transport in rabbit proximl tubules.

Show MeSH
Related in: MedlinePlus