Hemodynamically significant left main coronary artery stenosis(LMCA) is found in around 4% of diagnostic coronary angiograms and is known as unprotected LMCA stenosis if the left coronary artery and left cir-cumflex a...Hemodynamically significant left main coronary artery stenosis(LMCA) is found in around 4% of diagnostic coronary angiograms and is known as unprotected LMCA stenosis if the left coronary artery and left cir-cumflex artery has no previous patent grafts.Previous randomized studies have demonstrated a significant re-duction in mortality when revascularization by coronary artery bypass graft(CABG) surgery was undertaken compared with medical treatment.Therefore,current practice guidelines do not recommend percutaneous coronary intervention(PCI) for such a lesion because of the proven benefit of surgery and high rates of reste-nosis with the use of bare metal stents.However,with the advent of drug-eluting stents(DES),the long term outcomes of PCI with DES to treat unprotected LMCA stenoses have been acceptable.Therefore,apart from the current guidelines,PCI for treatment of unprotected LMCA stenosis is often undertaken in individuals who are at a very high risk of CABG or refuse to undergo a sternotomy.Future randomized studies comparing CABG vs PCI using DES for treatment of unprotected LMCA stenosis would be a great advance in clinical knowledge for the adoption of appropriate treatment.展开更多
AIM:The present study was designed to investigate the contribution of membrane hyperpolarization to endothelium-dependent relaxations induced by serotonin in the porcine coronary artery.METHODS:Rings with and without ...AIM:The present study was designed to investigate the contribution of membrane hyperpolarization to endothelium-dependent relaxations induced by serotonin in the porcine coronary artery.METHODS:Rings with and without endothelium of porcine coronary arteries were suspended in conventional organ chambers for the measurement of isometric force.The cell membrane potential of the vascular smooth muscle cells was measured using glass microelectrodes,in the presence of indometacin,ketanserin,and/or N^(ω)-nitro-L-arginine.RESULTS:Serotonin induced a transient endothelium-,and concentration-dependent relaxation in rings contracted with prostaglandin F_(2α)in the presence of N^(ω)-nitro-L-arginine(maximal relaxation;19%).The N^(ω)-nitro-L-arginine resistant relaxation was abolished by high K^(+)and tetrabutylammonium chloride.Serotonin also caused an endothelium-,concentration-dependent membrane hyperpolarizations with a maximal amplitude of-8.8mV.The nitro-L-arginine resistant relaxations and hyperpolarizations were abolished by methiothepin,but not by glibenclamide.The time course of the endothelium-dependent relaxations and hyperpolarizations was similar.CONCLUSION:These results suggest a contribution of cell membrane hyperpolarization to theendothelium-dependent relaxations induced by serotonin in the porcine coronary artery.展开更多
AIM: To determine the role of endothelium-derivedcontracting factor (EDCF) in the response toendothelin-1 in arteries with regenerated endothelium.METHODS: Rings of porcine coronary arteries, withand without endotheli...AIM: To determine the role of endothelium-derivedcontracting factor (EDCF) in the response toendothelin-1 in arteries with regenerated endothelium.METHODS: Rings of porcine coronary arteries, withand without endothelium of previously deendothelializedleft anterior descending coronary arteries and native leftcircumflex coronary arteries, were suspended inconventional organ chambers for the measurement ofisometric force. RESULTS: In quiescent rings of thepreviously deendothelialized left anterior展开更多
文摘Hemodynamically significant left main coronary artery stenosis(LMCA) is found in around 4% of diagnostic coronary angiograms and is known as unprotected LMCA stenosis if the left coronary artery and left cir-cumflex artery has no previous patent grafts.Previous randomized studies have demonstrated a significant re-duction in mortality when revascularization by coronary artery bypass graft(CABG) surgery was undertaken compared with medical treatment.Therefore,current practice guidelines do not recommend percutaneous coronary intervention(PCI) for such a lesion because of the proven benefit of surgery and high rates of reste-nosis with the use of bare metal stents.However,with the advent of drug-eluting stents(DES),the long term outcomes of PCI with DES to treat unprotected LMCA stenoses have been acceptable.Therefore,apart from the current guidelines,PCI for treatment of unprotected LMCA stenosis is often undertaken in individuals who are at a very high risk of CABG or refuse to undergo a sternotomy.Future randomized studies comparing CABG vs PCI using DES for treatment of unprotected LMCA stenosis would be a great advance in clinical knowledge for the adoption of appropriate treatment.
文摘AIM:The present study was designed to investigate the contribution of membrane hyperpolarization to endothelium-dependent relaxations induced by serotonin in the porcine coronary artery.METHODS:Rings with and without endothelium of porcine coronary arteries were suspended in conventional organ chambers for the measurement of isometric force.The cell membrane potential of the vascular smooth muscle cells was measured using glass microelectrodes,in the presence of indometacin,ketanserin,and/or N^(ω)-nitro-L-arginine.RESULTS:Serotonin induced a transient endothelium-,and concentration-dependent relaxation in rings contracted with prostaglandin F_(2α)in the presence of N^(ω)-nitro-L-arginine(maximal relaxation;19%).The N^(ω)-nitro-L-arginine resistant relaxation was abolished by high K^(+)and tetrabutylammonium chloride.Serotonin also caused an endothelium-,concentration-dependent membrane hyperpolarizations with a maximal amplitude of-8.8mV.The nitro-L-arginine resistant relaxations and hyperpolarizations were abolished by methiothepin,but not by glibenclamide.The time course of the endothelium-dependent relaxations and hyperpolarizations was similar.CONCLUSION:These results suggest a contribution of cell membrane hyperpolarization to theendothelium-dependent relaxations induced by serotonin in the porcine coronary artery.
基金Project supported in part by NIH grant HL 31547.
文摘AIM: To determine the role of endothelium-derivedcontracting factor (EDCF) in the response toendothelin-1 in arteries with regenerated endothelium.METHODS: Rings of porcine coronary arteries, withand without endothelium of previously deendothelializedleft anterior descending coronary arteries and native leftcircumflex coronary arteries, were suspended inconventional organ chambers for the measurement ofisometric force. RESULTS: In quiescent rings of thepreviously deendothelialized left anterior
