TY - JOUR
T1 - Kv7 channels critically determine coronary artery reactivity: left-right differences and down-regulation by hyperglycaemia
AU - Morales-Cano, Daniel
AU - Moreno, Laura
AU - Barreira, Bianca
AU - Pandolfi, Rachele
AU - Chamorro, Virginia
AU - Jimenez, Rosario
AU - Villamor, Eduardo
AU - Duarte, Juan
AU - Perez-Vizcaino, Francisco
AU - Cogolludo, Angel
PY - 2015/4/1
Y1 - 2015/4/1
N2 - Aims Voltage-gated potassium channels encoded by KCNQ genes (Kv7 channels) are emerging as important regulators of vascular tone. In this study, we analysed the contribution of Kv7 channels to the vasodilation induced by hypoxia and the cyclic AMP pathway in the coronary circulation. We also assessed their regional distribution and possible impairment by diabetes. Methods and results We examined the effects of Kv7 channel modulators on K+ currents and vascular reactivity in rat left and right coronary arteries (LCAs and RCAs, respectively). Currents from LCA were more sensitive to Kv7 channel inhibitors (XE991, linopirdine) and activators (flupirtine, retigabine) than those from RCA. Accordingly, LCAs were more sensitive than RCAs to the relaxation induced by Kv7 channel enhancers. Likewise, relaxation induced by the adenylyl cyclase activator forskolin and hypoxia, which were mediated through Kv7 channel activation, were greater in LCA than in RCA. KCNQ1 and KCNQ5 expression was markedly higher in LCA than in RCA. After incubation with high glucose (HG, 30 mmol/L), myocytes from LCA, but not from RCA, were more depolarized and showed reduced Kv7 currents. In HG-incubated LCA, the effects of Kv7 channel modulators and forskolin were diminished, and the expression of KCNQ1 and KCNQ5 was reduced. Finally, vascular responses induced by Kv7 channel modulators were impaired in LCA, but not in RCA, from type 1 diabetic rats. Conclusion Our results reveal that the high expression and function of Kv7 channels in the LCA and their down-regulation by diabetes critically determine the sensitivity to key regulators of coronary tone.
AB - Aims Voltage-gated potassium channels encoded by KCNQ genes (Kv7 channels) are emerging as important regulators of vascular tone. In this study, we analysed the contribution of Kv7 channels to the vasodilation induced by hypoxia and the cyclic AMP pathway in the coronary circulation. We also assessed their regional distribution and possible impairment by diabetes. Methods and results We examined the effects of Kv7 channel modulators on K+ currents and vascular reactivity in rat left and right coronary arteries (LCAs and RCAs, respectively). Currents from LCA were more sensitive to Kv7 channel inhibitors (XE991, linopirdine) and activators (flupirtine, retigabine) than those from RCA. Accordingly, LCAs were more sensitive than RCAs to the relaxation induced by Kv7 channel enhancers. Likewise, relaxation induced by the adenylyl cyclase activator forskolin and hypoxia, which were mediated through Kv7 channel activation, were greater in LCA than in RCA. KCNQ1 and KCNQ5 expression was markedly higher in LCA than in RCA. After incubation with high glucose (HG, 30 mmol/L), myocytes from LCA, but not from RCA, were more depolarized and showed reduced Kv7 currents. In HG-incubated LCA, the effects of Kv7 channel modulators and forskolin were diminished, and the expression of KCNQ1 and KCNQ5 was reduced. Finally, vascular responses induced by Kv7 channel modulators were impaired in LCA, but not in RCA, from type 1 diabetic rats. Conclusion Our results reveal that the high expression and function of Kv7 channels in the LCA and their down-regulation by diabetes critically determine the sensitivity to key regulators of coronary tone.
KW - Ion channels
KW - Potassium channels
KW - Vascular
KW - Hypoxia
KW - Diabetes mellitus
U2 - 10.1093/cvr/cvv020
DO - 10.1093/cvr/cvv020
M3 - Article
C2 - 25616413
SN - 0008-6363
VL - 106
SP - 98
EP - 108
JO - Cardiovascular Research
JF - Cardiovascular Research
IS - 1
ER -