Olsalazine Sodium Increases Renal Urate Excretion by Modulating Urate Transporters in Hyperuricemic Animals.

Hyperuricemia is mainly the result of relative underexcretion of urate. Urate is mainly eliminated by kidney and several important transporters expressed on the membrane of renal tubular cells involved in urate excretion. Olsalazine sodium was screened from 3167 authorized small compounds/drugs, targeting xanthine oxidoreductase. In previous study, we reported that olsalazine sodium significantly reduced the serum urate levels, and the anti-hyperuricemic activity linked with inhibiting urate formation by reducing the activity of xanthine oxidoreductase. The current research aimed to assess olsalazine sodium renal urate excretion and likely molecular mechanism. The results showed that administration of olsalazine sodium 5.0 mg/kg decreased the levels of serum urate in hyperuricemic rats, and noticeably improved the fractional excretion of urate and urate clearance, exhibiting an uricosuric action. Moreover, olsalazine sodium (2.5, 5.0, 10.0 mg/kg) reduced the level of blood urea nitrogen in rats. Further study showed that olsalazine sodium reduced the mRNA expression of urate reabsorptive transporter glucose transporter 9 (GLUT9), increased the mRNA expression of urate secretory transporters, organic anion transporter 1 (OAT1), OAT3 and type 1 sodium-dependent phosphate transporter (NPT1) as well as the protein expression of OAT3 in the kidney in hyperuricemic mice. In conclusion, olsalazine sodium exhibited a promotion of urate excretion in kidney by increasing the expression of OAT3.

Atorvastatin induces bile acid-synthetic enzyme Cyp7a1 by suppressing FXR signaling in both liver and intestine in mice.

Statins are effective cholesterol-lowering drugs to treat CVDs. Bile acids (BAs), the end products of cholesterol metabolism in the liver, are important nutrient and energy regulators. The present study aims to investigate how statins affect BA homeostasis in the enterohepatic circulation. Male C57BL/6 mice were treated with atorvastatin (100 mg/kg/day po) for 1 week, followed by BA profiling by ultra-performance LC-MS/MS. Atorvastatin decreased BA pool size, mainly due to less BA in the intestine. Surprisingly, atorvastatin did not alter total BAs in the serum or liver. Atorvastatin increased the ratio of 12α-OH/non12α-OH BAs. Atorvastatin increased the mRNAs of the BA-synthetic enzymes cholesterol 7α-hydroxylase (Cyp7a1) (over 10-fold) and cytochrome P450 27a1, the BA uptake transporters Na⁺/taurocholate cotransporting polypeptide and organic anion transporting polypeptide 1b2, and the efflux transporter multidrug resistance-associated protein 2 in the liver. Noticeably, atorvastatin suppressed the expression of BA nuclear receptor farnesoid X receptor (FXR) target genes, namely small heterodimer partner (liver) and fibroblast growth factor 15 (ileum). Furthermore, atorvastatin increased the mRNAs of the organic cation uptake transporter 1 and cholesterol efflux transporters Abcg5 and Abcg8 in the liver. The increased expression of BA-synthetic enzymes and BA transporters appear to be a compensatory response to maintain BA homeostasis after atorvastatin treatment. The Cyp7a1 induction by atorvastatin appears to be due to suppressed FXR signaling in both the liver and intestine.

Inhibitory and facilitory actions of isocyanine derivatives at human and rat organic cation transporters 1, 2 and 3: a comparison to human alpha 1- and alpha 2-adrenoceptor subtypes.

Organic cation transporters (OCTs), comprising OCT1, OCT2 and OCT3 subtypes, control absorption and elimination of xenobiotics and endogenous compounds in kidney, liver and placenta. In addition, they ensure "uptake2", low-affinity catecholamine clearance in sympathetically-innervated tissue and the CNS. The prototypical OCT ligand, disprocynium24 (D24), recognises OCT3, but its actions at OCT1 and OCT2 remain unknown. Herein, together with two other isocyanine derivatives (AAC291 and AAC301) and chemically-related adrenergic agents, we evaluated actions of D24 at OCTs, monoamine transporters and alpha(1)- and alpha(2)-adrenoceptors. D24 concentration-dependently suppressed [3H]-1-methyl-4-phenylpyridinium (MPP+) transport at human (h) and rat (r) OCT1, OCT2 and OCT3 in stably transfected HEK293 cells. Interestingly, low concentrations of D24 enhanced transport by h/rOCT2, a substrate-dependent effect suppressed by inhibition of protein kinase C. AAC291 and AAC301 likewise inhibited transport by all classes of h/r OCT and at low concentrations induced even more marked increases in transport by h/rOCT2. Further, by analogy to D24, they displayed antagonist properties at halpha(1A/B/D)-adrenoceptors (Ca2+-flux) and halpha(2A/B/C)-adrenoceptors ([35S]GTPgammaS binding). They were, however, less potent than D24 at serotonin transporters ([3H]citalopram binding) and AAC291 did not bind to dopamine and norepinephrine transporters. The preferential alpha(1B)-adrenoceptor antagonist, AH11110A, the alpha2-adrenoceptor agonist, RWJ52353, and the adrenergic neurotoxin DSP-4 likewise affected [3H]MPP+ transport, in an OCT-subtype and species-dependent manner. In conclusion, D24, other isocyanine congeners and chemically-related adrenergic agents inhibit OCT-mediated [3H]MPP+ transport, and all drugs display significant activity at alpha1- and alpha2-adrenoceptor subtypes, expanding previous reports of promiscuity between pharmacophores recognising alpha-adrenoceptors and OCTs.