title: Distinct mechanisms underlying cholesterol protection against alcohol-induced BK channel inhibition and resulting vasoconstriction.
abstract: Alcohol (ethanol) at concentrations reached in blood following moderate to heavy drinking (30-80mM) reduces cerebral artery diameter via inhibition of voltage- and calcium-gated potassium channels of large conductance (BK) in cerebral artery smooth muscle. These channels consist of channel-forming α and regulatory β1 subunits. A high-cholesterol diet protects against ethanol-induced constriction via accumulation of cholesterol within the vasculature. The molecular mechanisms of this protection remain unknown. In the present work, we demonstrate that in vitro cholesterol enrichment of rat middle cerebral arteries significantly increased cholesterol within arterial tissues and blunted constriction by 50mM of ethanol. Ethanol-induced BK channel inhibition in inside-out patches excised from freshly isolated cerebral artery myocytes was also abolished by cholesterol enrichment. Enrichment of arteries with enantiomeric cholesterol (ent-cholesterol) also blunted BK channel inhibition and cerebral artery constriction in response to ethanol. The similar protection of cholesterol and ent-cholesterol against ethanol action indicates that this protection does not require protein site(s) that specifically sense natural cholesterol. Cholesterol-driven protection against ethanol-induced BK channel inhibition and vasoconstriction was replicated in myocytes and middle cerebral arteries of C57BL/6 mice. BK β1 subunits are known to regulate vascular diameter and its modification by ethanol. However, blunting of an ethanol effect by in vitro cholesterol enrichment was observed in arteries and myocyte membrane patches from BK β1 (KCNMB1) knockout mice. Thus, BK β1 subunits are not needed for cholesterol protection against ethanol effect on BK channel function and cerebral artery diameter.
authors: Department of Pharmacology, The University of Tennessee Health Science Center, Memphis, TN 38163, USA.
authors: Shivantika
authors: S
authors: Bisen
authors: Department of Pharmacology, The University of Tennessee Health Science Center, Memphis, TN 38163, USA.
authors: Olga
authors: O
authors: Seleverstov
authors: Department of Chemistry, School of Physical Sciences, University of California, Irvine, 3038B FRH, Mail Code: 2025, Irvine, CA 92697, USA.
authors: Jitendra
authors: J
authors: Belani
authors: Department of Chemistry, School of Physical Sciences, University of California, Irvine, 3038B FRH, Mail Code: 2025, Irvine, CA 92697, USA.
authors: Scott
authors: S
authors: Rychnovsky
authors: Department of Pharmacology, The University of Tennessee Health Science Center, Memphis, TN 38163, USA.
authors: Alex M
authors: AM
authors: Dopico
authors: Department of Pharmacology, The University of Tennessee Health Science Center, Memphis, TN 38163, USA. Electronic address: abukiya@uthsc.edu.
authors: Anna N
authors: AN
authors: Bukiya
mesh_terms: D000818:Animals; D002536:Cerebral Arteries / Q000187:drug effects / Q000473:pathology; D002784:Cholesterol / Q000494:pharmacology*; D004032:Diet; D000431:Ethanol / Q000009:adverse effects*; D015640:Ion Channel Gating / Q000187:drug effects; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000037:antagonists & inhibitors* / Q000378:metabolism; D049990:Membrane Transport Modulators / Q000494:pharmacology; D008810:Mice, Inbred C57BL; D032342:Muscle Cells / Q000187:drug effects / Q000378:metabolism; D020011:Protective Agents / Q000494:pharmacology*; D021122:Protein Subunits / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D014661:Vasoconstriction / Q000187:drug effects*
chemical_list: D051036:Large-Conductance Calcium-Activated Potassium Channels; D049990:Membrane Transport Modulators; D020011:Protective Agents; D021122:Protein Subunits; D000431:Ethanol; D002784:Cholesterol
keywords: Cerebral artery; KCNMB1 knockout; Lipid-protein interaction; MaxiK channel; ent-Cholesterol