Hypoxic pulmonary hypertension(HPH) is a syndrome characterized by the increase of pulmonary vascular tone and the structural remodeling of peripheral pulmonary arteries.The aim of specific therapies for hypoxic pulmo...Hypoxic pulmonary hypertension(HPH) is a syndrome characterized by the increase of pulmonary vascular tone and the structural remodeling of peripheral pulmonary arteries.The aim of specific therapies for hypoxic pulmonary hypertension is to reduce pulmonary vascular resistance,reverse pulmonary vascular remodeling,and thereby improving right ventricular function.Iptakalim,a lipophilic para-amino compound with a low molecular weight,has been demonstrated to be a new selective ATP-sensitive potassium(K ATP) channel opener via pharmacological,electrophysiological,biochemical studies,and receptor binding tests.In hypoxia-induced animal models,iptakalim decreases the elevated mean pressure in pulmonary arteries,and attenuates remodeling in the right ventricle,pulmonary arteries and airways.Furthermore,iptakalim has selective antihypertensive effects,selective vasorelaxation effects on smaller arteries,and protective effects on endothelial cells,but no effects on the central nervous,respiratory,digestive or endocrine systems at therapeutic dose.Our previous studies demonstrated that iptakalim inhibited the effects of endothelin-1,reduced the intracellular calcium concentration and inhibited the proliferation of pulmonary artery smooth muscle cells.Since iptakalim has been shown safe and effective in both experimental animal models and phase I clinical trials,it can be a potential candidate of HPH in the future.展开更多
Increasing evidence, including from our laboratory, has revealed that opening of ATP sensitive potassium channels(K-ATP channels) plays the neuronal protective roles both in vivo and in vitro. Thus K-ATP channel opene...Increasing evidence, including from our laboratory, has revealed that opening of ATP sensitive potassium channels(K-ATP channels) plays the neuronal protective roles both in vivo and in vitro. Thus K-ATP channel openers(KCOs) have been proposed as potential neuroprotectants. Our previous studies demonstrated that K-ATP channels could regulate glutamate uptake activity in PC12 cells as well as in synaptosomes of rats. Since glutamate transporters(GluTs) of astrocytes play crucial roles in glutamate uptake and KATP channels are also expressed in astrocytes, the present study showed whether and how KATP channels regulated the function of GluTs in primary cultured astrocytes. The results showed that nonselective KCO pinacidil, selective mitochondrial KCO diazoxide, novel, and blood-brain barrier permeable KCO iptakalim could enhance glutamate uptake, except for the sarcolemmal KCO P1075. Moreover pinacidil, diazoxide, and iptakalim reversed the inhibition of glutamate uptake induced by 1-methyl-4-phenylpyridinium(MPP+). These potentiated effects were completely abolished by mitochondrial K-ATP blocker 5-hydroxydecanoate. Furthermore, either diazoxide or iptakalim could inhibit MPP+-induced elevation of reactive oxygen species (ROS) and phosphorylation of protein kinases C(PKC). These findings are the first to demonstrate that activation of K-ATP channel, especially mitochondrial K-ATP channel, improves the function of GluTs in astrocytes due to reducing ROS production and downregulating PKC phosphorylation. Therefore, the present study not only reveals a novel pharmacological profile of KCOs as regulators of GluTs, but also provides a new strategy for neuroprotection.展开更多
Cumulative evidence suggests that renal vascular endothelial injury play an important role in initiating and extending tubular epithelial injury and contribute to the development of ischemic acute renal failure.Our pr...Cumulative evidence suggests that renal vascular endothelial injury play an important role in initiating and extending tubular epithelial injury and contribute to the development of ischemic acute renal failure.Our previous studies have demonstrated that iptakalim's endothelium protection is related to activation of SUR2B/Kir6.1 subtype of ATP sensitive potassium channel(K ATP) in the endothelium.It has been reported that SUR2B/Kir6.1 channels are widely distributed in the tubular epithelium,glomerular mesangium,and the endothelium and the smooth muscle of blood vessels.Herein,we hypothesized that activating renal K ATP channels with iptakalim might have directly neroprotective effects.In this study,glomerular endothelial,mesangial and tubular epithelial cells which are the main cell types to form nephron were exposed to oleic acid(OA) at various concentrations for 24 h.0.25 μl/ml OA could cause cellular damage of glomerular endothelium and mesangium,while 1.25μl/ml OA could lead to the injury of three types of renal cells.It was observed that pretreatment with iptakalim at concentrations of 0.1,1,10 or 100 μmol/L prevented cellular damage of glomerular endothelium and tubular epithelium,whereas iptakalim from 1 to 100 μmol/L prevented the injury of mesangial cells.Our data showed iptakalim significantly increased survived cell rates in a concentration-dependent manner,significantly antagonized by glibenclamide,a K ATP blocker.Iptakalim played a protective role in the main cell types of kidney,which was consistent with natakalim,a highly selective SUR2B/Kir6.1 channel opener.Iptakalim exerted protective effects through activating SUR2B/Kir6.1 channels,suggesting a new strategy for renal injury by its endothelial and renal cell protection.展开更多
基金supported by National Major Scientific and Technological Special Project for"Significant New Drugs Development"(2011ZX09302-003-02)
文摘Hypoxic pulmonary hypertension(HPH) is a syndrome characterized by the increase of pulmonary vascular tone and the structural remodeling of peripheral pulmonary arteries.The aim of specific therapies for hypoxic pulmonary hypertension is to reduce pulmonary vascular resistance,reverse pulmonary vascular remodeling,and thereby improving right ventricular function.Iptakalim,a lipophilic para-amino compound with a low molecular weight,has been demonstrated to be a new selective ATP-sensitive potassium(K ATP) channel opener via pharmacological,electrophysiological,biochemical studies,and receptor binding tests.In hypoxia-induced animal models,iptakalim decreases the elevated mean pressure in pulmonary arteries,and attenuates remodeling in the right ventricle,pulmonary arteries and airways.Furthermore,iptakalim has selective antihypertensive effects,selective vasorelaxation effects on smaller arteries,and protective effects on endothelial cells,but no effects on the central nervous,respiratory,digestive or endocrine systems at therapeutic dose.Our previous studies demonstrated that iptakalim inhibited the effects of endothelin-1,reduced the intracellular calcium concentration and inhibited the proliferation of pulmonary artery smooth muscle cells.Since iptakalim has been shown safe and effective in both experimental animal models and phase I clinical trials,it can be a potential candidate of HPH in the future.
文摘Increasing evidence, including from our laboratory, has revealed that opening of ATP sensitive potassium channels(K-ATP channels) plays the neuronal protective roles both in vivo and in vitro. Thus K-ATP channel openers(KCOs) have been proposed as potential neuroprotectants. Our previous studies demonstrated that K-ATP channels could regulate glutamate uptake activity in PC12 cells as well as in synaptosomes of rats. Since glutamate transporters(GluTs) of astrocytes play crucial roles in glutamate uptake and KATP channels are also expressed in astrocytes, the present study showed whether and how KATP channels regulated the function of GluTs in primary cultured astrocytes. The results showed that nonselective KCO pinacidil, selective mitochondrial KCO diazoxide, novel, and blood-brain barrier permeable KCO iptakalim could enhance glutamate uptake, except for the sarcolemmal KCO P1075. Moreover pinacidil, diazoxide, and iptakalim reversed the inhibition of glutamate uptake induced by 1-methyl-4-phenylpyridinium(MPP+). These potentiated effects were completely abolished by mitochondrial K-ATP blocker 5-hydroxydecanoate. Furthermore, either diazoxide or iptakalim could inhibit MPP+-induced elevation of reactive oxygen species (ROS) and phosphorylation of protein kinases C(PKC). These findings are the first to demonstrate that activation of K-ATP channel, especially mitochondrial K-ATP channel, improves the function of GluTs in astrocytes due to reducing ROS production and downregulating PKC phosphorylation. Therefore, the present study not only reveals a novel pharmacological profile of KCOs as regulators of GluTs, but also provides a new strategy for neuroprotection.
基金supported by grants from National New Drug Research and Development of Key Project(2010ZX09401-307,2008ZX09101-006,2008ZXJ09004-018 and 2009ZX09301-002)
文摘Cumulative evidence suggests that renal vascular endothelial injury play an important role in initiating and extending tubular epithelial injury and contribute to the development of ischemic acute renal failure.Our previous studies have demonstrated that iptakalim's endothelium protection is related to activation of SUR2B/Kir6.1 subtype of ATP sensitive potassium channel(K ATP) in the endothelium.It has been reported that SUR2B/Kir6.1 channels are widely distributed in the tubular epithelium,glomerular mesangium,and the endothelium and the smooth muscle of blood vessels.Herein,we hypothesized that activating renal K ATP channels with iptakalim might have directly neroprotective effects.In this study,glomerular endothelial,mesangial and tubular epithelial cells which are the main cell types to form nephron were exposed to oleic acid(OA) at various concentrations for 24 h.0.25 μl/ml OA could cause cellular damage of glomerular endothelium and mesangium,while 1.25μl/ml OA could lead to the injury of three types of renal cells.It was observed that pretreatment with iptakalim at concentrations of 0.1,1,10 or 100 μmol/L prevented cellular damage of glomerular endothelium and tubular epithelium,whereas iptakalim from 1 to 100 μmol/L prevented the injury of mesangial cells.Our data showed iptakalim significantly increased survived cell rates in a concentration-dependent manner,significantly antagonized by glibenclamide,a K ATP blocker.Iptakalim played a protective role in the main cell types of kidney,which was consistent with natakalim,a highly selective SUR2B/Kir6.1 channel opener.Iptakalim exerted protective effects through activating SUR2B/Kir6.1 channels,suggesting a new strategy for renal injury by its endothelial and renal cell protection.
