Age-associated differences in transporter gene expression in kidneys of male rats.

Kidney transporters are involved in the secretion and reabsorption of endogenous and exogenous molecules. Numerous factors may influence their expression and affect drug disposition, efficacy and toxicity. The present study aimed to examine the development­ and age­associated variations in primary renal transporters in rats, including 6 uptake transporters: Organic anion transporter (OAT) 1 and 3, organic cation transporter (OCT) 1, 2 and 3 and organic anion­transporting polypeptide (OATP) 4C1, and 6 efflux transporters: Multidrug resistance protein 1 (MDR1), breast cancer resistance protein (BCRP), multidrug resistance­associated protein (MRP) 2 and 4, and multidrug and toxin extrusion protein (MATE) 1 and 2­K. Kidneys from male Sprague Dawley rats during development (­2, 1, 7, 14 and 21 days), maturation (28, 35 and 60 days) and aging (180, 540 and 850 days) were collected and total RNA was extracted, purified and subjected to reverse transcription­quantitative polymerase chain reaction analysis. Total proteins were extracted for western blot analysis. OAT1 and 3, OCT1, BCRP, MRP2 and 4 and MATE2­K expression levels were low in fetal kidneys, increased gradually following birth and markedly increased on maturation and adulthood. High levels were maintained until 850 days. OCT2, OATP4C1, Mdr1b and MATE1 expression levels were low in fetal kidneys, increased gradually following birth, and increased markedly on weaning, maturation and adulthood; however, levels were decreased on aging. OCT3 mRNA expression levels were low in fetal and newborn kidneys, and had two peaks at 35 and 850 days. The selected OAT1 and 3 and MDR1 protein expression levels revealed a similar expression pattern. Thus, kidney transporter expression is affected by ontogeny and aging, which may impact drug and toxicant disposition in children and the elderly.

1-Chloro-2-(4-phenyl-piperazin-1-yl)ethanone.

The title compound, C(12)H(15)ClN(2)O, is a piperazine derivative with the potential for use as a starting material for pharmaceutial and agrochemical applications. The structure is stabilized by C-H⋯O hydrogen bonds, C-H⋯π inter-actions and π-π stacking inter-actions [centroid-centroid distance = is 4.760 (2) Å].

Control of spermidine and spermine levels in rat tissues by trans-4-methylcyclohexylamine, a spermidine-synthase inhibitor.

In rat tissues, a decrease in spermidine, accompanied by an increase in spermine was induced by the oral administration (once daily for either 1 week or 1 month) of trans-4-methylcyclohexylamine (4MCHA), a spermidine synthase inhibitor. This is similar to the changes observed in polyamine content when cell growth is arrested. The body-weight gain of the rats tended to decrease with increasing doses of 4MCHA. A decrease in spermidine, combined with a moderate increase in spermine, was observed dose-dependently in all of the tissues tested, with a relatively fast clearance of 4MCHA. Manipulating the polyamine content of tissues, by daily administration of 100 mumol 4MCHA for 1 week, made it possible to estimate the effects of simultaneously added spermidine or spermine on endogenous polyamine contents. The altered polyamine levels, obtained after daily administration for 1 week, were maintained during the extended 1-month period, with growth-dependent alteration. The results show it is possible to produce experimental rats with a higher spermine:spermidine ratio than control rats to investigate the physiological significance of spermidine downregulation and spermine upregulation in vivo.

Fate of orally administered 15N-labeled polyamines in rats bearing solid tumors.

We studied absorption, distribution, metabolism, and excretion of polyamines (putrescine, spermidine, and spermine) in the gastrointestinal tract using (15)N-labeled polyamines as tracers and ionspray ionization mass spectrometry (IS-MS). The relatively simple protocol using rats bearing solid tumors provided useful information. Three (15)N-labeled polyamines that were simultaneously administered were absorbed equally from gastrointestinal tract, and distributed within tissues at various concentrations. The uptake of (15)N-spermidine seemed preferential to that of (15)N-spermine since the concentrations of (15)N-spermidine in the liver and tumors were higher, whereas those of (15)N-spermine were higher in the kidney, probably due to the excretion of excess extracellular spermine. Most of the absorbed (15)N-putrescine seemed to be lost, suggesting blood and tissue diamine oxidase degradation. Concentrations of (15)N-spermidine and (15)N-spermine in the tumor were low. We also describe the findings from two rats that were administered with (15)N-spermine. The tissue concentrations of (15)N-spermine were unusually high, and significant levels of (15)N-spermidine were derived from (15)N-spermine in these animals.

Simultaneous determination of endogenous and orally administered (15)N-labeled polyamines in rat organs.

A method for the simultaneous determination of polyamines (putrescine, spermidine, and spermine) by ionspray ionization-mass spectrometry was modified to determine (15)N-labeled polyamines together with unlabeled polyamines using (13)C,(15)N double-labeled polyamines as internal standards. This technique permitted the use of (15)N-labeled polyamines as tracer compounds to follow polyamine biosynthesis, interconversion, and absorption. The method was used to examine the organ distribution of orally administered (15)N-labeled polyamines in rats. Each (15)N-labeled polyamine was taken up by the three organs tested: the small intestine, liver, and kidney. The uptake of (15)N-labeled spermidine was greater than that of (15)N-labeled spermine and putrescine. Administration of a mixture of (15)N-labeled polyamines was useful for determining the disposition of each (15)N-polyamine absorbed from the intestinal tract.