1
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Bardsley EN, Paterson DJ. Neurocardiac regulation: from cardiac mechanisms to novel therapeutic approaches. J Physiol 2020; 598:2957-2976. [PMID: 30307615 PMCID: PMC7496613 DOI: 10.1113/jp276962] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 10/02/2018] [Indexed: 12/15/2022] Open
Abstract
Cardiac sympathetic overactivity is a well-established contributor to the progression of neurogenic hypertension and heart failure, yet the underlying pathophysiology remains unclear. Recent studies have highlighted the importance of acutely regulated cyclic nucleotides and their effectors in the control of intracellular calcium and exocytosis. Emerging evidence now suggests that a significant component of sympathetic overactivity and enhanced transmission may arise from impaired cyclic nucleotide signalling, resulting from compromised phosphodiesterase activity, as well as alterations in receptor-coupled G-protein activation. In this review, we address some of the key cellular and molecular pathways that contribute to sympathetic overactivity in hypertension and discuss their potential for therapeutic targeting.
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Affiliation(s)
- E. N. Bardsley
- Wellcome Trust OXION Initiative in Ion Channels and DiseaseOxfordUK
- Burdon Sanderson Cardiac Science Centre, Department of PhysiologyAnatomy and Genetics, University of OxfordOxfordOX1 3PTUK
| | - D. J. Paterson
- Wellcome Trust OXION Initiative in Ion Channels and DiseaseOxfordUK
- Burdon Sanderson Cardiac Science Centre, Department of PhysiologyAnatomy and Genetics, University of OxfordOxfordOX1 3PTUK
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2
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Shanks J, de Morais SDB, Gao L, Zucker IH, Wang HJ. TRPV1 (Transient Receptor Potential Vanilloid 1) Cardiac Spinal Afferents Contribute to Hypertension in Spontaneous Hypertensive Rat. Hypertension 2019; 74:910-920. [PMID: 31422690 DOI: 10.1161/hypertensionaha.119.13285] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hypertension is associated with increased sympathetic activity. A component of this sympathoexcitation may be driven by increased signaling from sensory endings from the heart to the autonomic control areas in the brain. This pathway mediates the so-called cardiac sympathetic afferent reflex, which is also activated by coronary ischemia or other nociceptive stimuli in the heart. The cardiac sympathetic afferent reflex has been shown to be enhanced in the heart failure state and in renal hypertension. However, little is known about its role in the development or progression of hypertension or the phenotype of the sensory endings involved. To investigate this, we used the selective afferent neurotoxin, resiniferatoxin (RTX) to chronically abolish the cardiac sympathetic afferent reflex in 2 models of hypertension; the spontaneous hypertensive rats (SHRs) and AngII (angiotensin II) infusion (240 ng/kg per min). Blood pressure (BP) was measured in conscious animals for 2 to 8 weeks post-RTX. Epidural application of RTX to the T1-T4 spinal segments prevented the further BP increase in 8-week-old SHR and lowered BP in 16-week-old SHR. RTX did not affect BP in Wistar-Kyoto normotensive rats nor in AngII-infused rats. Epicardial application of RTX (50 µg/mL) in 4-week-old SHR prevented the BP increase whereas this treatment does not lower BP in 16-week-old SHR. When RTX was administered into the L2-L5 spinal segments of 16-week-old SHR, no change in BP was observed. These findings indicate that signaling via thoracic afferent nerve fibers may contribute to the hypertension phenotype in the SHR but not in the Ang II infusion model of hypertension.
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Affiliation(s)
- Julia Shanks
- From the Department of Cellular and Integrative Physiology (J.S., S.D.B.d., L.G., I.H.Z., H.-J.W.), University of Nebraska Medical Center, Omaha, NE
| | - Sharon D B de Morais
- From the Department of Cellular and Integrative Physiology (J.S., S.D.B.d., L.G., I.H.Z., H.-J.W.), University of Nebraska Medical Center, Omaha, NE
| | - Lie Gao
- From the Department of Cellular and Integrative Physiology (J.S., S.D.B.d., L.G., I.H.Z., H.-J.W.), University of Nebraska Medical Center, Omaha, NE
| | - Irving H Zucker
- From the Department of Cellular and Integrative Physiology (J.S., S.D.B.d., L.G., I.H.Z., H.-J.W.), University of Nebraska Medical Center, Omaha, NE
| | - Han-Jun Wang
- From the Department of Cellular and Integrative Physiology (J.S., S.D.B.d., L.G., I.H.Z., H.-J.W.), University of Nebraska Medical Center, Omaha, NE.,Department of Anesthesiology (H.-J.W.), University of Nebraska Medical Center, Omaha, NE
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3
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Multiscale model of dynamic neuromodulation integrating neuropeptide-induced signaling pathway activity with membrane electrophysiology. Biophys J 2015; 108:211-23. [PMID: 25564868 DOI: 10.1016/j.bpj.2014.11.1851] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 10/21/2014] [Accepted: 11/11/2014] [Indexed: 02/07/2023] Open
Abstract
We developed a multiscale model to bridge neuropeptide receptor-activated signaling pathway activity with membrane electrophysiology. Typically, the neuromodulation of biochemical signaling and biophysics have been investigated separately in modeling studies. We studied the effects of Angiotensin II (AngII) on neuronal excitability changes mediated by signaling dynamics and downstream phosphorylation of ion channels. Experiments have shown that AngII binding to the AngII receptor type-1 elicits baseline-dependent regulation of cytosolic Ca(2+) signaling. Our model simulations revealed a baseline Ca(2+)-dependent response to AngII receptor type-1 activation by AngII. Consistent with experimental observations, AngII evoked a rise in Ca(2+) when starting at a low baseline Ca(2+) level, and a decrease in Ca(2+) when starting at a higher baseline. Our analysis predicted that the kinetics of Ca(2+) transport into the endoplasmic reticulum play a critical role in shaping the Ca(2+) response. The Ca(2+) baseline also influenced the AngII-induced excitability changes such that lower Ca(2+) levels were associated with a larger firing rate increase. We examined the relative contributions of signaling kinases protein kinase C and Ca(2+)/Calmodulin-dependent protein kinase II to AngII-mediated excitability changes by simulating activity blockade individually and in combination. We found that protein kinase C selectively controlled firing rate adaptation whereas Ca(2+)/Calmodulin-dependent protein kinase II induced a delayed effect on the firing rate increase. We tested whether signaling kinetics were necessary for the dynamic effects of AngII on excitability by simulating three scenarios of AngII-mediated KDR channel phosphorylation: (1), an increased steady state; (2), a step-change increase; and (3), dynamic modulation. Our results revealed that the kinetics emerging from neuromodulatory activation of the signaling network were required to account for the dynamical changes in excitability. In summary, our integrated multiscale model provides, to our knowledge, a new approach for quantitative investigation of neuromodulatory effects on signaling and electrophysiology.
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4
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Zion AS, Izzo JL. Combination therapy with aliskiren and amlodipine in hypertension: treatment rationale and clinical results. Expert Rev Cardiovasc Ther 2014; 9:421-7. [DOI: 10.1586/erc.11.23] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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5
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Wang G, Sarkar P, Peterson JR, Anrather J, Pierce JP, Moore JM, Feng J, Zhou P, Milner TA, Pickel VM, Iadecola C, Davisson RL. COX-1-derived PGE2 and PGE2 type 1 receptors are vital for angiotensin II-induced formation of reactive oxygen species and Ca(2+) influx in the subfornical organ. Am J Physiol Heart Circ Physiol 2013; 305:H1451-61. [PMID: 24014678 DOI: 10.1152/ajpheart.00238.2013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Regulation of blood pressure by angiotensin II (ANG II) is a process that involves the reactive oxygen species (ROS) and calcium. We have shown that ANG-II type 1 receptor (AT1R) and prostaglandin E2 (PGE2) type 1 receptors (EP1R) are required in the subfornical organ (SFO) for ROS-mediated hypertension induced by slow-pressor ANG-II infusion. However, the signaling pathway associated with this process remains unclear. We sought to determine mechanisms underlying the ANG II-induced ROS and calcium influx in mouse SFO cells. Ultrastructural studies showed that cyclooxygenase 1 (COX-1) codistributes with AT1R in the SFO, indicating spatial proximity. Functional studies using SFO cells revealed that ANG II potentiated PGE2 release, an effect dependent on AT1R, phospholipase A2 (PLA2) and COX-1. Furthermore, both ANG II and PGE2 increased ROS formation. While the increase in ROS initiated by ANG II, but not PGE2, required the activation of the AT1R/PLA2/COX-1 pathway, both ANG II and PGE2 were dependent on EP1R and Nox2 as downstream effectors. Finally, ANG II potentiated voltage-gated L-type Ca(2+) currents in SFO neurons via the same signaling pathway required for PGE2 production. Blockade of EP1R and Nox2-derived ROS inhibited ANG II and PGE2-mediated Ca(2+) currents. We propose a mechanism whereby ANG II increases COX-1-derived PGE2 through the AT1R/PLA2 pathway, which promotes ROS production by EP1R/Nox2 signaling in the SFO. ANG II-induced ROS are coupled with Ca(2+) influx in SFO neurons, which may influence SFO-mediated sympathoexcitation. Our findings provide the first evidence of a spatial and functional framework that underlies ANG-II signaling in the SFO and reveal novel targets for antihypertensive therapies.
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Affiliation(s)
- Gang Wang
- The Brain and Mind Research Institute, Weill Cornell Medical College, New York, New York
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6
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Sharma NM, Zheng H, Li YF, Patel KP. Nitric oxide inhibits the expression of AT1 receptors in neurons. Am J Physiol Cell Physiol 2012; 302:C1162-73. [PMID: 22218225 DOI: 10.1152/ajpcell.00258.2011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have previously observed an increased of angiotensin II (ANG II) type 1 receptor (AT(1)R) with enhanced AT(1)R-mediated sympathetic outflow and concomitant downregulation of neuronal nitric oxide (NO) synthase (nNOS) with reduced NO-mediated inhibition from the paraventricular nucleus (PVN) in rats with heart failure. To test the hypothesis that NO exerts an inhibitory effect on AT(1)R expression in the PVN, we used primary cultured hypothalamic cells of neonatal rats and neuronal cell line NG108-15 as in vitro models. In hypothalamic primary culture, NO donor sodium nitroprusside (SNP) induced dose-dependent decreases in mRNA and protein of AT(1)R (10(-5) M SNP, AT(1)R protein was 10 ± 2% of control level) while NOS inhibitor N(G)-monomethyl-l-arginine (l-NMMA) induced dose-dependent increases in mRNA and protein levels of AT(1)R (10(-5) M l-NMMA, AT(1)R protein was 148 ± 8% of control level). Similar effects of SNP and l-NMMA on AT(1)R expression were also observed in NG108-15 cell line (10(-6) M SNP, AT(1)R protein was 30 ± 4% of control level while at the dose of 10(-6) M l-NMMA, AT(1)R protein was 171 ± 15% of the control level). Specific inhibition of nNOS, using antisense, caused an increase in AT(1)R expression while overexpression of nNOS, using adenoviral gene transfer (Ad.nNOS), caused an inhibition of AT(1)R expression in NG108 cells. Antisense nNOS transfection augmented the increase while Ad.nNOS infection blunted the increase in intracellular calcium concentration in response to ANG II treatment in NG108 cells. In addition, downregulation of AT(1)R mRNA as well as protein level in neuronal cell line in response to S-nitroso-N-acetyl pencillamine (SNAP) treatment was blocked by protein kinase G (PKG) inhibitor, while the peroxynitrite scavenger deforxamine had no effect. These results suggest that NO acts as an inhibitory regulator of AT(1)R expression and the activation of PKG is the required step in the regulation of AT(1)R gene expression via cGMP-dependent signaling pathway.
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Affiliation(s)
- Neeru M Sharma
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, 68198-5850, USA
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7
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Izzo JL, Zion AS. Combined aliskiren-amlodipine treatment for hypertension in African Americans: clinical science and management issues. Ther Adv Cardiovasc Dis 2011; 5:169-78. [PMID: 21606125 DOI: 10.1177/1753944711409615] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
While it may seem at first that antihypertensive drug combinations run counter to the desire to 'personalize' the management of hypertension, the best combinations have predictable efficacy in different individuals and subpopulations. Race is probably not a valid surrogate for clinically meaningful genetic variation or guide to therapy. Most guidelines suggest similar blood pressure goals for different races but drug treatment recommendations have diverged. In the United States, race is not considered to be a major factor in drug choice, but in England and other countries, initial therapy with renin-angiotensin system blocking drugs is not recommended in Blacks. In this review we: (1) examine new trends in race-based research; (2) emphasize the weaknesses of race-based treatment recommendations; and (3) explore the effects of a new combination, renin inhibition (aliskiren) and amlodipine, in African Americans.
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Affiliation(s)
- Joseph L Izzo
- Department of Medicine, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, 462 Grider Street, Buffalo, NY 14215, USA.
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8
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Teschemacher AG, Wang S, Raizada MK, Paton JFR, Kasparov S. Area-specific differences in transmitter release in central catecholaminergic neurons of spontaneously hypertensive rats. Hypertension 2008; 52:351-8. [PMID: 18606900 DOI: 10.1161/hypertensionaha.108.114371] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The link among blood pressure, sympathetic output, and brain neurons producing catecholamines is well documented. Nevertheless, their intrinsic properties and any alterations in signaling characteristics between normotensive and hypertensive phenotypes remain unknown. Here, we directly compared neurophysiological properties of catecholamine release of C1 and A2 neurons of the spontaneously hypertensive rat and Wistar rat in organotypic slices. C1 and A2 areas were studied because both are widely implicated in the pathophysiology of hypertension. Catecholaminergic neurons were visualized using viral vectors to express green fluorescent protein. Microamperometry revealed that C1 axonal varicosities of spontaneously hypertensive but not normotensive Wistar rats release a transmitter predominantly (approximately 86%) in very large quanta, comparable in catecholamine load to adrenal chromaffin granules. Because quantal size affects the spread of transmitter in the extracellular space, this may enhance the impact of C1 varicosities on their downstream targets and increase sympathetic drive in the hypertensive rat. Electrophysiological properties and Ca2+ handling were studied using patch clamp and confocal imaging. Although overall electrophysiological characteristics of C1 and A2 neurons were comparable between strains, the characteristic angiotensin-II-induced Ca2+ mobilization was reduced in A2 neurons of the spontaneously hypertensive rat. Because A2 neurons are a part of a homeostatic antihypertensive circuit, this could reduce their restraining influence on blood pressure. Thus, we have revealed an increased quantal size in C1 varicosities and a reduced responsiveness of A2 neurons of the spontaneously hypertensive rat to angiotensin II. Both effects could contribute to elevated sympathetic activity and blood pressure in the spontaneously hypertensive rat.
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Affiliation(s)
- Anja G Teschemacher
- Department of Physiology and Pharmacology, University of Bristol, School of Medical Sciences, University Walk, Bristol BS81TD, United Kingdom
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9
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Shim CY, Ha JW, Park S, Choi EY, Choi D, Rim SJ, Chung N. Exaggerated Blood Pressure Response to Exercise Is Associated With Augmented Rise of Angiotensin II During Exercise. J Am Coll Cardiol 2008; 52:287-92. [DOI: 10.1016/j.jacc.2008.03.052] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Revised: 03/10/2008] [Accepted: 03/10/2008] [Indexed: 10/21/2022]
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10
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Wang S, Teschemacher AG, Paton JFR, Kasparov S. Mechanism of nitric oxide action on inhibitory GABAergic signaling within the nucleus tractus solitarii. FASEB J 2006; 20:1537-9. [PMID: 16720728 DOI: 10.1096/fj.05-5547fje] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The cellular mechanisms mediating nitric oxide (NO) modulation of the inhibitory transmission in the nucleus tractus solitarii (NTS) remain unclear, even though this could be extremely important for various physiological and pathological processes. Specifically, in the NTS NO-evoked glutamate and gamma-aminobutyric acid (GABA) release might contribute to pathological hypertension. In cultured rat brainstem slices, NTS GABAergic neurons were targeted using an adenoviral vector to express enhanced green fluorescent protein and studied with a combination of patch clamp and confocal microscopy. Low nanomolar concentrations of NO increased intracellular Ca2+ concentration ([Ca2+]i) in somata, dendrites, and putative axons of GABAergic neurons, with axons being the most sensitive compartment. This effect was cGMP mediated and not related to depolarization or indirect presynaptic effects on glutamatergic transmission. Blockade of the cyclic adenosine diphosphate ribose (cADPR)/ryanodine-sensitive stores but not the inositol triphosphate-sensitive stores, inhibited NO effect. Since cADPR/ryanodine-sensitive stores are implicated in the Ca2+-induced Ca2+ release, NO can be expected to potentiate GABA release. In support of this notion, a cADPR antagonist abolished the NO-induced potentiation of GABAergic inhibitory postsynaptic potentials in the NTS. Thus, the NO-cGMP-cADPR-Ca2+ pathway, previously described in sea urchin eggs, also operates in mammalian GABAergic neurons. Potentiation of GABA release by NO may have implications for numerous brain functions.
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Affiliation(s)
- Sheng Wang
- Department of Physiology, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK
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11
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Krum H, Mohacsi P, Katus HA, Tendera M, Rouleau JL, Fowler MB, Coats AJ, Roecker EB, Packer M. Are beta-blockers needed in patients receiving spironolactone for severe chronic heart failure? An analysis of the COPERNICUS study. Am Heart J 2006; 151:55-61. [PMID: 16368292 DOI: 10.1016/j.ahj.2005.03.054] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2004] [Accepted: 03/01/2005] [Indexed: 12/31/2022]
Abstract
BACKGROUND The beneficial effects of beta-blockers and aldosterone receptor antagonists are now well established in patients with severe systolic chronic heart failure (CHF). However, it is unclear whether beta-blockers are able to provide additional benefit in patients already receiving aldosterone antagonists. We therefore examined this question in the COPERNICUS study of 2289 patients with severe CHF receiving the beta1-beta2/alpha1 blocker carvedilol compared with placebo. METHODS Patients were divided post hoc into subgroups according to whether they were receiving spironolactone (n = 445) or not (n = 1844) at baseline. Consistency of the effect of carvedilol versus placebo was examined for these subgroups with respect to the predefined end points of all-cause mortality, death or CHF-related hospitalizations, death or cardiovascular hospitalizations, and death or all-cause hospitalizations. RESULTS The beneficial effect of carvedilol was similar among patients who were or were not receiving spironolactone for each of the 4 efficacy measures. For all-cause mortality, the Cox model hazard ratio for carvedilol compared with placebo was 0.65 (95% CI 0.36-1.15) in patients receiving spironolactone and 0.65 (0.51-0.83) in patients not receiving spironolactone. Hazard ratios for death or all-cause hospitalization were 0.76 (0.55-1.05) versus 0.76 (0.66-0.88); for death or cardiovascular hospitalization, 0.61 (0.42-0.89) versus 0.75 (0.64-0.88); and for death or CHF hospitalization, 0.63 (0.43-0.94) versus 0.70 (0.59-0.84), in patients receiving and not receiving spironolactone, respectively. The safety and tolerability of treatment with carvedilol were also similar, regardless of background spironolactone. CONCLUSION Carvedilol remained clinically efficacious in the COPERNICUS study of patients with severe CHF when added to background spironolactone in patients who were practically all receiving angiotensin-converting enzyme inhibitor (or angiotensin II antagonist) therapy. Therefore, the use of spironolactone in patients with severe CHF does not obviate the necessity of additional treatment that interferes with the adverse effects of sympathetic activation, specifically beta-blockade.
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Affiliation(s)
- Henry Krum
- Monash University, Melbourne, Australia.
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12
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Kimura S, Abe Y. [Cardiac oxidative stress: interaction between angiotensin and adrenaline receptors]. Nihon Yakurigaku Zasshi 2005; 126:251-5. [PMID: 16327205 DOI: 10.1254/fpj.126.251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
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13
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Sakic B, Kirkham DL, Ballok DA, Mwanjewe J, Fearon IM, Macri J, Yu G, Sidor MM, Denburg JA, Szechtman H, Lau J, Ball AK, Doering LC. Proliferating brain cells are a target of neurotoxic CSF in systemic autoimmune disease. J Neuroimmunol 2005; 169:68-85. [PMID: 16198428 PMCID: PMC1634761 DOI: 10.1016/j.jneuroim.2005.08.010] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2005] [Accepted: 08/01/2005] [Indexed: 12/31/2022]
Abstract
Brain atrophy, neurologic and psychiatric (NP) manifestations are common complications in the systemic autoimmune disease, lupus erythematosus (SLE). Here we show that the cerebrospinal fluid (CSF) from autoimmune MRL-lpr mice and a deceased NP-SLE patient reduce the viability of brain cells which proliferate in vitro. This detrimental effect was accompanied by periventricular neurodegeneration in the brains of autoimmune mice and profound in vivo neurotoxicity when their CSF was administered to the CNS of a rat. Multiple ionic responses with microfluorometry and protein peaks on electropherograms suggest more than one mechanism of cellular demise. Similar to the CSF from diseased MRL-lpr mice, the CSF from a deceased SLE patient with a history of psychosis, memory impairment, and seizures, reduced viability of the C17.2 neural stem cell line. Proposed mechanisms of cytotoxicity involve binding of intrathecally synthesized IgG autoantibodies to target(s) common to different mammalian species and neuronal populations. More importantly, these results indicate that the viability of proliferative neural cells can be compromised in systemic autoimmune disease. Antibody-mediated lesions of germinal layers may impair the regenerative capacity of the brain in NP-SLE and possibly, brain development and function in some forms of CNS disorders in which autoimmune phenomena have been documented.
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Affiliation(s)
- Boris Sakic
- Department of Psychiatry and Behavioural Neurosciences, HSC Rm 4N81, McMaster University, 1200 Main St. West, Hamilton, Ontario, Canada L8N 3Z5
- * Corresponding author. Tel.: +1 905 525 9140x22617, 22850; fax: +1 905 522 8804. E-mail addresses: (B. Sakic), (D.L. Kirkham), (D.A. Ballok), (J. Mwanjewe), (I.M. Fearon), (J. Macri), (G. Yu), (M.M. Sidor), (J.A. Denburg), (H. Szechtman), (J. Lau), (A.K. Ball), (L.C. Doering)
| | - David L. Kirkham
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Canada
| | - David A. Ballok
- Department of Psychiatry and Behavioural Neurosciences, HSC Rm 4N81, McMaster University, 1200 Main St. West, Hamilton, Ontario, Canada L8N 3Z5
| | - James Mwanjewe
- Department of Medicine, McMaster University, Hamilton, Canada
| | - Ian M. Fearon
- Department of Biology, McMaster University, Hamilton, Canada
| | - Joseph Macri
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Canada
| | - Guanhua Yu
- Department of Psychiatry and Behavioural Neurosciences, HSC Rm 4N81, McMaster University, 1200 Main St. West, Hamilton, Ontario, Canada L8N 3Z5
| | - Michelle M. Sidor
- Department of Psychiatry and Behavioural Neurosciences, HSC Rm 4N81, McMaster University, 1200 Main St. West, Hamilton, Ontario, Canada L8N 3Z5
| | | | - Henry Szechtman
- Department of Psychiatry and Behavioural Neurosciences, HSC Rm 4N81, McMaster University, 1200 Main St. West, Hamilton, Ontario, Canada L8N 3Z5
| | - Jonathan Lau
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Canada
| | - Alexander K. Ball
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Canada
| | - Laurie C. Doering
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Canada
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14
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Fernandez SF, Huang MH, Davidson BA, Knight PR, Izzo JL. Mechanisms of Angiotensin II–Mediated Decreases in Intraneuronal Ca
2+
in Calcium-Loaded Stellate Ganglion Neurons. Hypertension 2005; 45:276-82. [PMID: 15642775 DOI: 10.1161/01.hyp.0000153320.13842.43] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Our laboratory has reported previously that angiotensin II, type-1 (AT
1
) receptor stimulation in isolated stellate ganglion neurons decreases intraneuronal calcium concentration ([Ca
2+
]i) acutely if baseline [Ca
2+
]i is high and increases [Ca
2+
]i if baseline [Ca
2+
]i is low. Part of the angiotensin II (Ang II) effect in high Ca
2+
neurons is mediated through stimulation of Na
+
–Ca
2+
exchange. Current experiments were conducted to identify additional steps in the signaling pathways. In Ca
2+
-loaded neurons, Ang II–induced decreases in [Ca
2+
]i were attenuated by phospholipase C inhibition (U73122) or nitric oxide (NO) synthase inhibition (
l
-NMMA) and were mimicked by the cGMP analogue 8-Br-cGMP. Protein kinase C (PKC) inhibition (bisindolylmaleimide I or Go6976) and protein kinase G (PKG) inhibition (KT5823) partially blocked Ang II–mediated decreases in [Ca
2+
]i, but complete blockade of Ang II effects was obtained with combined PKC and PKG inhibition. Modulation of inositol triphosphate (IP
3
)-inducible ER Ca
2+
release by [Ca
2+
]i was investigated using furaptra, an ER-retaining dye. IP
3
-mediated ER Ca
2+
release in β-escin–permeabilized neurons was measured after clamping of [Ca
2+
]i from 50 nM to 800 nM. Maximal ER Ca
2+
release was observed at ≈200 nM [Ca
2+
]i, with noted blunting of release at higher [Ca
2+
]i. Steady-state mRNA transcript and protein levels revealed that the principal IP
3
R isoform expressed was IP
3
R-II. These results suggest that Ca
2+
loading in stellate ganglion neurons promotes Ang II-mediated decreases in [Ca
2+
]i via PKC and NO/cGMP/PKG pathways and inhibits IP
3
R-II–mediated ER Ca
2+
release.
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Affiliation(s)
- Stanley F Fernandez
- Department of Pharmacology, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, USA
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15
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Kimura S, Zhang GX, Nagai Y, Miyata K, Nishiyama A, Shokoji T, Yao L, Fan YY, Rahman M, Fujisawa Y, Miyatake A, Abe Y. Time-dependent transition of tempol-sensitive reduction of blood pressure in angiotensin II-induced hypertension. J Hypertens 2004; 22:2161-8. [PMID: 15480101 DOI: 10.1097/00004872-200411000-00019] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE Reactive oxygen species (ROS) participate in the intracellular signalling of angiotensin II. However, the mechanisms of the interaction of ROS with hypertension and mitogen-activated protein kinase (MAPK) in vivo have remained unclear. Angiotensin II infusion provokes sustained hypertension accompanied with enhancement of ROS production; initially hypertension is non-sensitive to ROS, but thereafter becomes sensitive. We examined the time-dependent transition of ROS-sensitive vasoconstriction during angiotensin II infusion and also ROS sensitivity to cardiovascular MAPK activation in acutely and chronically angiotensin II-infused rats. METHODS AND RESULTS During infusion of a pressor dose of angiotensin II to conscious Sprague-Dawley rats, tempol, a superoxide dismutase mimetic, was administered at 10 min, some 1, 3, 6, 12 and 24 h after the start of infusion. The magnitude of the reduction in blood pressure by tempol was initially negligible, but gradually enlarged, and reached a maximum of 96% of delta increase by angiotensin II at 12 h. However, even after sensitization to tempol, superimposed angiotensin II enabled an increase of blood pressure under tempol treatment. In chronically angiotensin II-infused rats, superimposed angiotensin II exhibited tempol quenchable MAPK activation. CONCLUSIONS These results indicate that the mechanisms of angiotensin II-induced vasoconstriction may shift from being non-sensitive to ROS to sensitive within 12 h; nevertheless, both ROS non-sensitive vasoconstriction and ROS-sensitive MAPK activation by angiotensin II, which are both seen in the acute phase of infusion, are restored in the late maintaining phase of prolonged angiotensin II infusion.
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Affiliation(s)
- Shoji Kimura
- Department of Pharmacology, Research Equipment Center and Radioisotope Research Center, Kagawa University Medical School, Kagawa, Japan
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