Relationship between 2,4,5-trichlorophenoxyacetate and the renal organic base transport system

Koschier, Francis J.; Berndt, William O.

doi:10.1016/0006-2952(77)90149-6

Cited by 14 publications

(4 citation statements)

References 13 publications

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“…The fact that NMN efflux was signif icantly greater than that for TEA was consis tent with the observation of poor net accu mulation of the nicotinamide derivative, and similar to observations in other species (8). However, because no net accumulation oc curred with NMN it is not clear what these runout data mean.…”

Section: Discussionmentioning

confidence: 52%

“…Based on interactions of TEA transport with 2,4,5-T. a similar renal handling ofTEA was proposed for the rat (8). The absence of selectivity in cation binding by rat cytosol is not consistent with this hypothesis, however.…”

Section: Discussionmentioning

confidence: 55%

“…For example, most workers suggest that anion and cation trans port are quite separate in the kidney (2,7). Nonetheless, despite the apparent selectivity, significant interactions between organic ca tions and organ anions have been re ported (8).…”

Section: Introductionmentioning

confidence: 99%

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Organic Base Transport: a Comparative Study

Berndt¹

1981

Pharmacology

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Many studies have been reported in which the renal transport of the organic cations, tetraethylammonium (TEA) and N’-methylnicotinamide (NMN) have been studied. This study was designed to examine the renal handling of these two organic cations by two species, the rat and the rabbit. As reported by others, the renal slice accumulation of NMN by rabbit tissue was poor, with slice/medium (S/M) ratios never exceeding 1. In rat tissue, both cations were accumulated with S/M ratios varying from 4 to 15. Kinetic data support earlier proposals for a dual uptake process for TEA, whereas a single uptake component appeared from NMN in rabbit tissue. NMN uptake by rabbit renal cortex slices was not altered significantly by alterations in bathing solution potassium (0–80 mM), sodium (15–150 mM), or calcium concentrations. TEA uptake in rabbit tissue also was unaffected by alterations in electrolyte concentrations of the bathing solution, with S/M ratios near 10 at all electrolyte concentrations. Significant binding of both cations to renal cortical cytosol was observed. TEA binding to rabbit renal cortical cytosol was reduced with increasing concentrations of TEA. NMN binding to rabbit cytosol increased with increasing cation concentrations in the bathing solution. With rat cytosol, both cations were bound from 6 to 10%, and the binding was unaffected by alterations in cation concentrations. In subcellular fractionation studies in both species, TEA showed a higher binding in the initial low-speed fraction and a lower binding in the final supernatant than did NMN. The extent of TEA binding in the low-speed fractions was reduced significantly by incubation of the homogenates with 10^-3Af 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). 2,4,5-T had no effect on the subcellular distribution of NMN in either rat or rabbit tissue. Unidirectional runout studies indicated that NMN efflux from preloaded rabbit renal cortex slices was faster than that for TEA. The NMN runout rate constants were similar to those reported earlier for rat tissue. The relatively slow efflux of TEA from rabbit renal cortical tissue was unaffected by phenoxybenzamine, cyanine No. 863, NMN, or alterations in bathing solution potassium concentration. On the other hand, effects on NMN efflux were observed.

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Section: Discussionmentioning

confidence: 52%

Section: Discussionmentioning

confidence: 55%

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Organic Base Transport: a Comparative Study

Berndt¹

1981

Pharmacology

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“…Under acute conditions, it is possible that the effect on P AH transport is a competitive one, since citrinin is an organic anion and shows clearance values consistent with renal tubular secretion (Phillips et al, 1980b). However, a competitive effect of citrinin on TEA (tetraethylammonium) transport is considerably less likely, although an interaction of organic anion and organic cation transport has been reported for some substances (Koschier and Berndt, 1977). After pretreatment, virtually all of the administered citrinin had disappeared by 48 hr (see below; Phillips et al, 1979) and yet the effects of citrinin on P AH and TEA transport still persisted.…”

Section: Effects Of Citrinin On Renal Transport Mechanismsmentioning

confidence: 94%