Binge drinking is associated with increased risk for cerebrovascular spasm and stroke. Acute exposure to ethanol at concentrations obtained during binge drinking constricts cerebral arteries in several species, including humans, but the mechanisms underlying this action are largely unknown. In a rodent model, we used fluorescence microscopy, patch-clamp electrophysiology, and pharmacological studies in intact cerebral arteries to pinpoint the molecular effectors of ethanol cerebrovascular constriction. Clinically relevant concentrations of ethanol elevated wall intracellular Ca 2؉ concentration and caused a reversible constriction of cerebral arteries (EC50 ‫؍‬ 27 mM; Emax ‫؍‬ 100 mM) that depended on voltage-gated Ca 2؉ entry into myocytes. However, ethanol did not directly increase voltage-dependent Ca 2؉ currents in isolated myocytes. Constriction occurred because of an ethanol reduction in the frequency (؊53%) and amplitude (؊32%) of transient Ca 2؉ -activated K ؉ (BK) currents. Ethanol inhibition of BK transients was caused by a reduction in Ca 2؉ spark frequency (؊49%), a subsarcolemmal Ca 2؉ signal that evokes the BK transients, and a direct inhibition of BK channel steady-state activity (؊44%). In contrast, ethanol failed to modify Ca 2؉ waves, a major vasoconstrictor mechanism. Selective block of BK channels largely prevented ethanol constriction in pressurized arteries. This study pinpoints the Ca 2؉ spark͞BK channel negative-feedback mechanism as the primary effector of ethanol vasoconstriction.M oderate-heavy episodic alcohol intake, such as in binge drinking, remains a major public health problem (1, 2). Moderate-heavy drinking is associated, independently of any other factor, with an increased risk for stroke and deaths from ischemic stroke (3, 4). Binge drinkers are significantly predisposed to brain hemorrhage, cerebrovascular spasm, and stroke (3, 5).Cerebrovascular disease associated with moderate-heavy alcohol intake is independent of beverage type and alcohol metabolism but linked to ethanol (EtOH) itself (6, 7). Strong evidence for a dose-response relationship between EtOH intake and risk for stroke suggests causality (8). EtOH cerebral artery constriction is considered responsible for cerebral vasospasm, ischemia, and stroke in moderate-heavy drinkers (6, 9). Acute EtOH at legally intoxicating (Ն20 mM) blood levels in naive subjects constricts cerebral arteries in several species, including humans (7, 9).Rats are excellent models to study EtOH cerebral artery constriction and stroke (7,10,11). Evidence from this and other species indicates that EtOH constricts cerebral arteries by acting primarily on the smooth muscle (7,11,12). However, the molecular mechanisms mediating EtOH cerebral artery constriction remain largely unidentified.In cerebrovascular smooth muscle, an elevation in global intracellular Ca 2ϩ ([Ca 2ϩ ] ic ) leads to contraction (13). Ca 2ϩ mobilization in response to EtOH may result from direct potentiation of mechanisms leading to Ca 2ϩ influx͞release from internal organel...

The small-world organization has been hypothesized to reflect a balance between local processing and global integration in the human brain. Previous multimodal imaging studies have consistently demonstrated that the topological architecture of the brain network is disrupted in Alzheimer's disease (AD). However, these studies have reported inconsistent results regarding the topological properties of brain alterations in AD. One potential explanation for these inconsistent results lies with the diverse homogeneity and distinct progressive stages of the AD involved in these studies, which are thought to be critical factors that might affect the results. We investigated the topological properties of brain functional networks derived from resting functional magnetic resonance imaging (fMRI) of carefully selected moderate AD patients and normal controls (NCs). Our results showed that the topological properties were found to be disrupted in AD patients, which showing increased local efficiency but decreased global efficiency. We found that the altered brain regions are mainly located in the default mode network, the temporal lobe and certain subcortical regions that are closely associated with the neuropathological changes in AD. Of note, our exploratory study revealed that the ApoE genotype modulates brain network properties, especially in AD patients.

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Abstract-Vasoconstrictors that bind to phospholipase C-coupled receptors elevate inositol-1,4,5-trisphosphate (IP 3 The mechanism by which IP 3 regulates arterial contractility is generally well accepted. 1 Indeed, IP 3 -induced SR Ca 2ϩ release is considered to be the only mechanism by which this second messenger regulates arterial diameter. However, the physiological mechanisms by which IP 3 regulates intracellular Ca 2ϩ signaling and arterial diameter are poorly understood, and few studies have directly tested the accepted view. Arterial contractility regulation by IP 3 has primarily been studied by using vasoconstrictors that activate PLC. Because PLC activation elevates both DAG and IP 3 and reduces PIP 2 , mechanisms by which IP 3 specifically modulates arterial [Ca 2ϩ ] i signaling and diameter require additional study. Here, we investigated IP 3 regulation of ion channel activity, intracellular Ca 2ϩ signaling, and contractility in cerebral artery myocytes and pressurized arteries. We show that IP 3 activates a nonselective cation current (I Cat ) in myocytes and induces vasoconstriction via a mechanism that does not require the release of SR Ca 2ϩ but involves IP 3 R and TRPC3 (canonical transient receptor potential 3) channel activation. IP 3 -induced Na ϩ influx produces membrane depolarization, voltage-dependent Ca 2ϩ channel activation, an [Ca 2ϩ ] i elevation, and vasoconstriction. We also show that TRPC3 channel Original

Abstract-Mitochondria regulate intracellular calcium (Ca 2ϩ ) signals in smooth muscle cells, but mechanisms mediating these effects, and the functional relevance, are poorly understood. Similarly, antihypertensive ATP-sensitive potassium (K ATP ) channel openers (KCOs) activate plasma membrane K ATP channels and depolarize mitochondria in several cell types, but the contribution of each of these mechanisms to vasodilation is unclear. Here, we show that cerebral artery smooth muscle cell mitochondria are most effectively depolarized by diazoxide (Ϫ15%, tetramethylrhodamine [TMRM]), less so by levcromakalim, and not depolarized by pinacidil. KCO-induced mitochondrial depolarization increased the generation of mitochondria-derived reactive oxygen species (ROS) that stimulated Ca 2ϩ sparks and large-conductance Ca 2ϩ -activated potassium (K Ca ) channels, leading to transient K Ca current activation. KCO-induced mitochondrial depolarization and transient K Ca current activation were attenuated by 5-HD and glibenclamide, K ATP channel blockers. MnTMPyP, an antioxidant, and Ca 2ϩ spark and K Ca channel blockers reduced diazoxide-induced vasodilations by Ͼ60%, but did not alter dilations induced by pinacidil, which did not elevate ROS. Data suggest diazoxide drives ROS generation by inducing a small mitochondrial depolarization, because nanomolar CCCP, a protonophore, similarly depolarized mitochondria, elevated ROS, and activated transient K Ca currents. In contrast, micromolar CCCP, or rotenone, an electron transport chain blocker, induced a large mitochondrial depolarization (Ϫ84%, TMRM), reduced ROS, and inhibited transient K Ca currents. In summary, data demonstrate that mitochondriaderived ROS dilate cerebral arteries by activating Ca 2ϩ sparks, that some antihypertensive KCOs dilate by stimulating this pathway, and that small and large mitochondrial depolarizations lead to differential regulation of ROS Here, we demonstrate that a small mitochondrial depolarization, such as that induced by diazoxide, leads to the generation of reactive oxygen species (ROS) that elevate Ca 2ϩ spark frequency and increase the effective coupling of Ca 2ϩ sparks to K Ca channels in arterial smooth muscle cells, resulting in vasodilation. Data also indicate that small and large mitochondrial depolarizations lead to differential regulation of ROS and Ca 2ϩ sparks. This study identifies a novel mechanism by which mitochondria regulate local and global Ca 2ϩ signaling and arterial diameter. Materials and Methods Tissue PreparationAnimal procedures used were approved by the Animal Tetramethylrhodamine, Methyl Ester ImagingExperiments were performed using HEPES-buffered PSS containing (in mM): 134 NaCl, 6 KCl, 2 CaCl 2 , 1 MgCl 2 , 10 HEPES, and 10 glucose (pH 7.4, NaOH). Cells were incubated in HEPES-buffered PSS containing tetramethylrhodamine (TMRM) (100 nM) for 20 minutes, followed by a 15-minute wash. TMRM localization was identified by excitation with 543 nm light, and emission light Ͼ560 nm was captured using a Zeiss LSM5 con...