title: Endothelial AMP-activated protein kinase regulates blood pressure and coronary flow responses through hyperpolarization mechanism in mice.
abstract: OBJECTIVE
  Vascular endothelium plays an important role to maintain cardiovascular homeostasis through several mechanisms, including endothelium-dependent hyperpolarization (EDH). We have recently demonstrated that EDH is involved in endothelial metabolic regulation in mice. However, it remains to be examined whether AMP-activated protein kinase (AMPK), an important metabolic regulator, is involved in EDH and if so, whether endothelial AMPK (eAMPK) plays a role for circulatory regulation.
  
  
  RESULTS
  We examined the role of eAMPK in EDH, using mice with endothelium-specific deficiency of α-catalytic subunit of AMPK, either α1 (eAMPKα1 (-/-)α2 (+/+)) or α2 (eAMPKα1 (+/+)α2 (-/-)) alone or both of them (eAMPKα1 (-/-)α2 (-/-)). We performed telemetry, organ chamber, electrophysiological, and Langendorff experiments to examine blood pressure, vascular responses, hyperpolarization of membrane potential, and coronary flow responses, respectively. Hypertension was noted throughout the day in eAMPKα1 (-/-)α2 (-/-) and eAMPKα1 (-/-)α2 (+/+) but not in eAMPKα1 (+/+)α2 (-/-) mice when compared with respective control. Importantly, endothelium-dependent relaxations, EDH, and coronary flow increase were all significantly reduced in eAMPKα1 (-/-)α2 (-/-) and eAMPKα1 (-/-)α2 (+/+) but not in eAMPKα1 (+/+)α2 (-/-) mice. In contrast, endothelium-independent relaxations to sodium nitroprusside (a NO donor), NS-1619 (a Ca(2+)-activated K(+) channel opener), and exogenous H2O2 were almost comparable among the groups. In eAMPKα1 (-/-)α2 (-/-) mice, antihypertensive treatment with hydralazine or long-term treatment with metformin (a stimulator of AMPK) failed to restore EDH-mediated responses.
  
  
  CONCLUSIONS
  These results provide the first direct evidence that α1 subunit of eAMPK substantially mediates EDH responses of microvessels and regulates blood pressure and coronary flow responses in mice in vivo, demonstrating the novel role of eAMPK in cardiovascular homeostasis.
authors.affiliation: From the Department of Cardiovascular Medicine, Tohoku University, Sendai, Japan.
authors.forename: Budbazar
authors.initials: B
authors.lastname: Enkhjargal
authors.affiliation: From the Department of Cardiovascular Medicine, Tohoku University, Sendai, Japan.
authors.forename: Shigeo
authors.initials: S
authors.lastname: Godo
authors.affiliation: From the Department of Cardiovascular Medicine, Tohoku University, Sendai, Japan.
authors.forename: Ayuko
authors.initials: A
authors.lastname: Sawada
authors.affiliation: From the Department of Cardiovascular Medicine, Tohoku University, Sendai, Japan.
authors.forename: Nergui
authors.initials: N
authors.lastname: Suvd
authors.affiliation: From the Department of Cardiovascular Medicine, Tohoku University, Sendai, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Saito
authors.affiliation: From the Department of Cardiovascular Medicine, Tohoku University, Sendai, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Noda
authors.affiliation: From the Department of Cardiovascular Medicine, Tohoku University, Sendai, Japan.
authors.forename: Kimio
authors.initials: K
authors.lastname: Satoh
authors.affiliation: From the Department of Cardiovascular Medicine, Tohoku University, Sendai, Japan. shimo@cardio.med.tohoku.ac.jp.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Shimokawa
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D006332:Cardiomegaly / Q000201:enzymology / Q000235:genetics / Q000503:physiopathology; D003326:Coronary Circulation / Q000187:drug effects; D003331:Coronary Vessels / Q000187:drug effects / Q000201:enzymology* / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology* / Q000503:physiopathology; D006973:Hypertension / Q000201:enzymology / Q000235:genetics / Q000503:physiopathology; D008297:Male; D008564:Membrane Potentials; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D015398:Signal Transduction; D013997:Time Factors; D014655:Vascular Resistance; D014664:Vasodilation; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D000959:Antihypertensive Agents; D014665:Vasodilator Agents; C548179:Prkaa1 protein, mouse; C534978:Prkaa2 protein, mouse; D055372:AMP-Activated Protein Kinases
keywords: AMP-activated protein kinases; blood pressure; endothelial cells; endothelium-dependent hyperpolarization factor