B Washington

Tennessee State University, Nashville, TN, United States

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Publications (6)9.37 Total impact

  • J B Shaw, Q Cai, C Mtshali, E L Myles, B Washington
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    ABSTRACT: Specific binding of [3H]-N-alpha-methylhistamine to homogenates from cerebral cortex tissue was analyzed in aged Wistar Kyoto (WKY) and Spontaneously Hypertensive rats (SHR). Scatchard plot analysis of [3H]-N-alpha-methylhistamine binding of the H3 receptor in the cerebral cortex from aged (6, 9, 12, and 16 week) SHR animals indicated that Bmax increased, respectively, 38.05 +/- 1.58, 59.63 +/- 2.48, 79.17 +/- 5.02, and 84.41 +/- 3.72 fmol/mg of protein. Binding studies using tissue from WKY rats indicated that maximal binding (Bmax) of the ligand to the receptor was not significantly altered. The analyses also yielded Kd values of 5, 7.2, 6.3 and 3.8 nM in SHR tissue respectively. Primers based on the sequence of the third intracellular loop of the H3 receptor were amplified at 35 cycles yielding several amplicons. These amplicons expressed sizes 875, 485, and 280 bp in 6 and 9 week cortical tissue from WKY animals where as in cortical tissue from 6 and 9 week SHR animals only two amplicons were expressed, 485 and 280 bp, respectively. Differences in gene expression for 12 and 16 week WKY and SHR rats were also compared using identical primers. Five amplicons were expressed in cortical tissue from 12 and 16 week WKY rats with 1000, 900, 821, 485, and 430 bp where as in 12 and 16 week SHR animals only one amplicon was expressed at 485 bp. The present results imply (1) that H3 receptor density in cortical tissue of SHR animals increases with age where as the number of the expressed amplicons of the detected H3 receptor decreases; and (2) even though a decrease in number of expressed amplicons of the H3 receptor were observed, an increase in expression of the larger amplicon (~500 bp) is evident.
    Cellular and molecular biology (Noisy-le-Grand, France) 02/2007; 53(4):45-50. · 1.46 Impact Factor
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    ABSTRACT: Histamine (HA) is one of many neurotransmitters that have been implicated in cardiovascular functioning. Alterations in vascular smooth muscle due to the effects of histamine have been suggested. We investigated the modulatory effect of HA on mitogen activated protein kinase (MAPK) expression, specifically extracellular regulating kinase (ERK) 1 & 2 in vascular smooth muscle cells (VSMCs) from both spontaneously hypertensive (SHR) and control Wistar Kyoto (WKY) rats. Cross-talking between calcium (Ca2+) and HA during HA-induced modulatory effect on MAPK expression in SHR VSMCs was also investigated. A stimulatory increase in expression of ERK 1 & 2 was observed to be dose and time dependent with maximum expression occurring within 5 min in both SHR and WKY VSMCs. The stimulatory increase in expression is persistent for 60 min in SHR VSMCs, whereas, in WKY cells the stimulatory effect persists for only 20 min. Mepyramine, the H1 receptor antagonist, reduced the HA-induced increase in ERK 1 & 2 significantly in SHR VSMCs. A reduction in the HA stimulated increase in ERK 1 & 2 expression was observed at 20 min of exposing cells to diltiazem, the calcium channel blocker, whereas, the calcium chelator, BAPTA effect on ERK 1 & 2 expression was observed within 5 min in SHR VSMCs. The data demonstrates that cross-talking occurs between HA stimulation and Ca2+ induction during HA-induced activation of ERK 1 & 2 in VSMCs of both cell types. Although both intracellular calcium ([Ca2+]i) and extracellular Ca2+ maybe involved in the activation of ERK 1 & 2 by HA, the dependence on [Ca2+]i is more dramatic than the dependence on extracellular Ca2+ in hypertensive cells, which may contribute to the role of HA as a risk factor of hypertension in VSMCs of the aorta.
    Cellular and molecular biology (Noisy-le-Grand, France) 01/2007; 53(4):61-6. · 1.46 Impact Factor
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    ABSTRACT: Protein Kinase C (PKC) exists as one of twelve serine/threonine isoforms and has been found to mediate ethanol-induced activation of the Mitogen-Activated Protein Kinase (MAPK) pathway. The aim of this study was to determine the PKC isoform(s) that are mediators of ethanol-induced MAPK activity (ERK 1 and 2) and to verify the necessity of calcium in this activation process using cell culture in the presence and absence of ethanol, and other agents that modulate PKC expression. Western blotting analysis was used to assess the effect of ethanol on activating classical (alpha/ssII), novel (delta) and atypical (zeta/lambda) PKC isoforms in vascular smooth muscle cells (VSMCs). The results indicate that ethanol treated VSMCs express the classical PKC-alpha/ssII, novel PKC-delta, and atypical PKC-zeta/lambda isoforms. The expression of PKC-alpha/ssII was inhibited within the first two min of stimulation, followed by activation with maximum expression at 10 min. Similarly, PKC-delta and zeta expressions were suppressed during the first two min of ethanol stimulation with maximum increase in expressions at 10 min. The PKC inhibitor GF109203X and the calcium chelating agent BAPTA, enhanced ethanol-induced PKC expression, whereas, diltiazem reduced expression of PKC by 10% of control. On the other hand, BAPTA in the presence of GF10203X inhibited expression of ERK 1 & 2 downstream from the PKC pathway, whereas, BAPTA alone enhanced expression. These results demonstrate also that classical, novel, and atypical PKCs respond to ethanol during the initial phase of activation of ERK 1 & 2.
    Cellular and molecular biology (Noisy-le-Grand, France) 01/2007; 53(4):38-44. · 1.46 Impact Factor
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    ABSTRACT: Cadmium (Cd) is frequently used in various industrial applications and is a ubiquitous environmental toxicant, also present in tobacco smoke. An important route of exposure is the circulatory system whereas blood vessels are considered to be main stream organs of Cd toxicity. Our previous results indicate that cadmium chloride (CdCl2) affects mean arterial blood pressure in hypertensive rats. We hypothesized that Cd alters the intracellular calcium transient mechanism, by cadmium-induced stimulation of MAPKs (ERK 1 & 2) which is mediated partially through calcium-dependent PKC mechanism. To investigate this hypothesis, we exposed primary cultures of vascular smooth muscle cells (VSMCs) from wistar kyoto (WKY) and spontaneously hypertensive rats (SHR) to increased concentrations of CdCl2 on cell viability, expression of mitogen-activated protein kinases (MAPKs/ERK 1 & 2), and protein kinase C (PKC) which are activated by Cd in several cell types. The results from these studies indicate that CdCl2 decreased cell viability of both SHR and WKY VSMCs in a concentration dependent-manner. Viability of both cell types decreased 33+/-5.3 (SHR) and 39+/-2.3% (WKY) when exposed to 1 microM CdCl2, whereas, 8 and 16 microM reduced viability by 66+/-3.1 and 62+/-4.5% in SHR cells. CdCl2 increased ERK 1 & 2 in a biphasic manner with maximum increase occurring when cells are exposed to 1 and 4 muM in SHR VSMCs, whereas, a reduction in ERK 1 and 2 is observed when WKY cells are treated with 2 microM. The results also indicate that CdCl2 increased PKC a/Beta in both SHR and WKY VSMCs with a greater increase in expression in SHR VSMCs. In addition, the [Ca2+]i chelator, BAPTA, suppressed the CdCl2 effect, whereas, the PKC inhibitor, GF109203X, reduced the CdCl2 induced-effect on PKC expression. The present studies support the hypothesis that Cd can be a risk factor of hypertension through dysfunction of vascular smooth muscle cells under certain conditions.
    International journal of environmental research and public health 12/2006; 3(4):323-8. · 1.61 Impact Factor
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    ABSTRACT: The aim of this study was to determine the pathway(s) by which ethanol activates mitogen-activated protein kinase (MAPK) signaling and to determine the role of Ca2+ in the signaling process. MAPK signaling was determined by assessing MAPK activity, measuring phosphorylated extracellular signaling-regulated kinase (pp 44 ERK-1 and pp 42 ERK-2) expression and ERK activity by measuring ERK-2-dependent phosphorylation of a synthetic peptide as a MAPK substrate in rat vascular smooth muscle cells. Ethanol activated extracellular signal-regulated kinase expression (ERK 1 and 2) could be observed when vascular smooth muscle cells (VSMCs) were stimulated for 5 min or less, but was inhibited when cells are treated for 10 min or more with 1-16 mM of ethanol. Maximum ethanol-induced MAPK activity was observed within 5 min with 4 or 8 mM. Ethanol stimulated MAPK activity was blocked by the protein kinase C (PKC) inhibitor (GF109203X) and epidermal growth factor (EGF) receptor antagonist (PD153035) by 41 +/- 24 and 34 +/- 12.3%, respectively. The calcium channel blocker, diltiazem and the chelating agent, BAPTA, reduced the activation of MAPK activity by ethanol, significantly. The data demonstrate that ethanol-stimulated MAPK expression is mediated partially through both the EGF-receptor and PKC intermediates and that activation through the PKC intermediate is calcium-dependent.
    Cellular and molecular biology 01/2004; 49(8):1351-6. · 0.81 Impact Factor
  • B Washington, J B Shaw, J Li, B Fisher, J Gwathmey
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    ABSTRACT: The in vivo mechanisms underlying the actions of modulating Na(+)- and Ca(2+)-sensitive channels and its effect on basal histamine release in the cerebral cortex of freely-moving unanesthetized rats was investigated. Basal histamine release in the cerebral cortex was determined by in vivo microdialysis coupled with high-performance liquid chromatography (HPLC) fluorometry detection. Basal levels of histamine were 0.67+/-0.02 pmol/10 microl of dialysate. Diltiazem, a Ca(2+) channel antagonist, produced a dose-dependent decrease in dialysate basal histamine concentration. Elevated K(+) (100 mM) in the perfusion medium increased basal histamine to a maximum of 223% of the baseline value. Similarly, diltiazem (60 mM) reduced the K(+), veratridine (100 microg/ml) and ouabain (100 microM)-evoked increase in dialysate histamine. Basal histamine decreased by 48% when the perfusate contained 3 microM of voltage dependent Na(+) antagonist tetrodotoxin. The results of these studies indicate that the release of histamine in rat cerebral cortex can be induced by modulating Na(+) and Ca(2+) channels and that the L-type voltage-dependent sensitive Ca(2+) channels are involved in this release process.
    European Journal of Pharmacology 11/2000; 407(1-2):117-22. · 2.59 Impact Factor