Change in pharmacological effect of endothelin receptor antagonists in rats with pulmonary hypertension: role of ETB-receptor expression levels.
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BACKGROUND AND PURPOSE: The endothelin (ET) system is activated in pulmonary arterial hypertension (PAH). The therapeutic value of pharmacological blockade of ET receptors has been demonstrated in various animal models and led to the current approval and continued development of these drugs for the therapy of human PAH. However, we currently incompletely comprehend what local modifications of this system occur as a consequence of PAH, particularly in small resistance arteries, and how this could affect the pharmacological response to ET receptor antagonists with various selectivities for the receptor subtypes. Therefore, the purposes of this study were to evaluate potential modifications of the pharmacology of the ET system in rat pulmonary resistance arteries from monocrotaline (MCT)-induced pulmonary arterial hypertension. EXPERIMENTAL APPROACH: ET-1 levels were quantified by ELISA. PreproET-1, ETA and ETB receptor mRNA expressions were quantified in pulmonary resistance arteries using Q-PCR, while protein expression was evaluated by Western blots. Reactivity to ET-1 of isolated pulmonary resistance arteries was measured in the presence of ETA (A-147627), ETB (A-192621) and dual ETA/B (bosentan) receptor antagonists. KEY RESULTS: In rats with PAH, plasma ET-1 increased (p < 0.001) while pulmonary levels were reduced(p < 0.05). In PAH arteries, preproET-1 (p < 0.05) and ETB receptor (p < 0.001) gene expressions were reduced, as were ETB receptor protein levels (p < 0.05). ET-1 induced similar vasoconstrictions in both groups. In arteries from sham animals, neither bosentan nor the ETA or the ETB receptor antagonists modified the response. In arteries from PAH rats, however, bosentan and the ETA receptor antagonist potently reduced the maximal contraction, while bosentan also reduced sensitivity (p < 0.01). CONCLUSIONS AND IMPLICATIONS: The effectiveness of both selective ETA and dual ETA/B receptor antagonists is markedly increased in PAH. Down-regulation of pulmonary resistance arteries ETB receptor may contribute to this finding. (+info)
A transgenic mouse model of inducible macrophage depletion: effects of diphtheria toxin-driven lysozyme M-specific cell lineage ablation on wound inflammatory, angiogenic, and contractive processes.
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Early combined treatment with cilostazol and bone marrow-derived endothelial progenitor cells markedly attenuates pulmonary arterial hypertension in rats.
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A rare case of brucine poisoning complicated by rhabdomyolysis and acute renal failure.
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Brucine is the predominant alkaloid present in the bark of the tree Strychnos nux vomica and is a weaker alkaloid when compared to strychnine. However, its toxicological property is akin to strychnine. We report a rare case of brucine poisoning complicated by acute renal failure and rhabdomyolysis. A 24-year-old male presented with a history of consumption of a decoction made from the bark of the Strychnos nux vomica tree. Soon after, he developed widespread muscle spasms and convulsions, which were promptly treated. On the fifth day of admission, he developed features of rhabdomyolysis and acute renal failure. Investigations revealed elevated creatine phosphokinase levels and elevated blood urea and serum creatinine. The patient was managed with hemodialysis and recovered gradually. There are many reports of strychnine poisoning producing rhabdomyolysis and renal failure. In this case report, attention is drawn to the fact that brucine, although a weaker alkaloid, can also produce life threatening complications like rhabdomyolysis and acute renal failure. (+info)
Structural perturbations induced by the alpha-anomer of the aflatoxin B(1) formamidopyrimidine adduct in duplex and single-strand DNA.
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Tadalafil, a long-acting inhibitor of PDE5, improves pulmonary hemodynamics and survival rate of monocrotaline-induced pulmonary artery hypertension in rats.
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The aim of this study was to assess the effect of tadalafil (0.5, 2.5, and 10 mg/kg per day) on the progression of pulmonary arterial hypertension (PAH) in early treatment and on the survival rate in late treatment on the monocrotaline (MCT)-induced PAH rat model. Tadalafil was administered once daily to rats for 3 weeks from the day of MCT-injection or 21 days after the injection. With early treatment, tadalafil at 10 mg/kg per day prevented the development of PAH by maintaining mean pulmonary artery pressure within the normal range and attenuated right ventricular hypertrophy. With late treatment, tadalafil tended to increase the partial pressure of oxygen in arterial blood and dose-dependently improved the survival rate by 55%, 60%, and 70% at 0.5, 2.5, and 10 mg/kg per day, respectively, versus 40% in the MCT-control group. Both early and late treatments with tadalafil were associated with elevated lung cyclic guanosine monophosphate (cGMP). These results suggest that tadalafil relaxes pulmonary arteries by elevating cGMP in lungs and extend survival time by improving pulmonary hemodynamics even when treatment occurs in the late phase of PAH. Thus, it is expected that tadalafil may be an effective, once-daily treatment option in humans with PAH. (+info)