Mechanism of quercetin improving rat coronary artery myogenic re-sponse under high glucose / 中国病理生理杂志

ABSTRACT

AIM:To investigate the mechanism of quercetin improving rat coronary artery myogenic response under high glucose ( HG) by measuring muscle tension of coronary arterial ring and recording voltage -gated K +channel ( Kv) current of coronary artery smooth muscle cells by whole cell patch clamp .METHODS:The coronary rings from the normal SD rats were acutely isolated , and then divided into 6 groups:(1) control group;(2) HG group;(3) HG+low dose (3 μmol/L) of quercetin group;(4) HG+moderate dose (10 μmol/L) of quercetin group; (5) HG+high dose (30 μmol/L) of quercetin group;(6) HG+C6303 (PKC inhibitor) +high dose of quercetin group.Determinations of coronary artery response to vasoconstrictor (60 mmol/L KCl or 0.1 mmol/L U46619) or vasodilator (Ach at 10 -9 ~10 -5 mol/L) were performed, and the percentage of coronary ring tension was calculated using the contraction as 100%caused by 60 mmol/L KCl.The rat coronary artery smooth muscle cells were acutely isolated for recording the Kv current using whole cell patch clamp .RESULTS:Compared with control group , the contraction amplitudes to 60 mmol/L KCl or 0.1 mmol/L U46619 were significantly increased under HG incubation .Quercetin intervention concentration-dependently re-duced the coronary artery contraction amplitude .Incubation of PKC specific inhibitor C 6303 attenuated the effect of querce-tin.Compared with control group , the diastolic amplitude to Ach decreased significantly in HG group , and quercetin inter-vention concentration-dependently increased the coronary artery diastolic amplitude .Incubation of PKC specific inhibitor C6303 attenuated the effect of quercetin .Compared with control group , HG incubation inhibited Kv current of coronary ar-tery vascular smooth muscle cells significantly , and quercetin intervention attenuated the inhibitory effect of HG on Kv cur-rent intensity .Incubation of PKC specific inhibitor C 6303 attenuated the effect of quercetin .CONCLUSION: Quercetin has a protective effect on myogenic response of coronary artery under HG and the effects is related to the increase in Kv cur -rent and the activation of PKC in vascular smooth muscle cells .