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Cui YX, Du JB, Jin HF. Baroreflex sensitivity and its implication in neurally mediated syncope in children. World J Pediatr 2023; 19:1023-1029. [PMID: 37014537 DOI: 10.1007/s12519-023-00693-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 01/20/2023] [Indexed: 04/05/2023]
Affiliation(s)
- Ya-Xi Cui
- Department of Pediatrics, Peking University First Hospital, Beijing, 100034, China
| | - Jun-Bao Du
- Department of Pediatrics, Peking University First Hospital, Beijing, 100034, China
- Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, 100191, China
| | - Hong-Fang Jin
- Department of Pediatrics, Peking University First Hospital, Beijing, 100034, China.
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Makowska K, Gonkowski S. Changes Caused by Low Doses of Bisphenol A (BPA) in the Neuro-Chemistry of Nerves Located in the Porcine Heart. Animals (Basel) 2021; 11:ani11030780. [PMID: 33799766 PMCID: PMC7999793 DOI: 10.3390/ani11030780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/07/2021] [Accepted: 03/08/2021] [Indexed: 12/20/2022] Open
Abstract
Simple Summary Bisphenol A (BPA) is a substance commonly used in the plastics industry, which is a part of many everyday items. It may leach from plastics and penetrate food, water, soil and air. It is known that BPA negatively affects living organisms. It impairs the functions of the intestine, neurons, reproductive organs, endocrine glands and immune cells. Previous studies have also reported that BPA negatively influences the cardiovascular system, leading to heart arrhythmia, intensification of atherosclerosis, blood hypertension and increased risk of a heart attack. However, many aspects of the influence of BPA on the heart are still poorly understood. One of these aspects is the BPA impact on heart innervation. Therefore, this article aimed to investigate the influence of low doses of BPA on the number of nerves containing selected active substances taking part in neuronal stimuli conduction located in the porcine heart apex. The results indicate that even relatively low doses of BPA are not neutral to the cardiovascular system, because they affect the neurochemical characterization of nerves in the heart. These changes may underlie the negative effects of BPA on the heart. Abstract Bisphenol A (BPA) contained in plastics used in the production of various everyday objects may leach from these items and contaminate food, water and air. As an endocrine disruptor, BPA negatively affects many internal organs and systems. Exposure to BPA also contributes to heart and cardiovascular system dysfunction, but many aspects connected with this activity remain unknown. Therefore, this study aimed to investigate the impact of BPA in a dose of 0.05 mg/kg body weight/day (in many countries such a dose is regarded as a tolerable daily intake–TDI dose of BPA–completely safe for living organisms) on the neurochemical characterization of nerves located in the heart wall using the immunofluorescence technique. The obtained results indicate that BPA (even in such a relatively low dose) increases the number of nerves immunoreactive to neuropeptide Y, substance P and tyrosine hydroxylase (used here as a marker of sympathetic innervation). However, BPA did not change the number of nerves immunoreactive to vesicular acetylcholine transporter (used here as a marker of cholinergic structures). These observations suggest that changes in the heart innervation may be at the root of BPA-induced circulatory disturbances, as well as arrhythmogenic and/or proinflammatory effects of this endocrine disruptor. Moreover, changes in the neurochemical characterization of nerves in the heart wall may be the first sign of exposure to BPA.
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Affiliation(s)
- Krystyna Makowska
- Department of Clinical Diagnostics, Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn, Oczapowskiego 14, 10-957 Olsztyn, Poland
- Correspondence: ; Tel.: +48-44895234460
| | - Slawomir Gonkowski
- Department of Clinical Physiology, Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn, Oczapowskiego 13, 10-957 Olsztyn, Poland;
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Tan CMJ, Green P, Tapoulal N, Lewandowski AJ, Leeson P, Herring N. The Role of Neuropeptide Y in Cardiovascular Health and Disease. Front Physiol 2018; 9:1281. [PMID: 30283345 PMCID: PMC6157311 DOI: 10.3389/fphys.2018.01281] [Citation(s) in RCA: 115] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 08/24/2018] [Indexed: 12/20/2022] Open
Abstract
Neuropeptide Y (NPY) is an abundant sympathetic co-transmitter, widely found in the central and peripheral nervous systems and with diverse roles in multiple physiological processes. In the cardiovascular system it is found in neurons supplying the vasculature, cardiomyocytes and endocardium, and is involved in physiological processes including vasoconstriction, cardiac remodeling, and angiogenesis. It is increasingly also implicated in cardiovascular disease pathogenesis, including hypertension, atherosclerosis, ischemia/infarction, arrhythmia, and heart failure. This review will focus on the physiological and pathogenic role of NPY in the cardiovascular system. After summarizing the NPY receptors which predominantly mediate cardiovascular actions, along with their signaling pathways, individual disease processes will be considered. A thorough understanding of these roles may allow therapeutic targeting of NPY and its receptors.
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Affiliation(s)
- Cheryl M J Tan
- Oxford Cardiovascular Clinical Research Facility, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Peregrine Green
- Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre, University of Oxford, Oxford, United Kingdom
| | - Nidi Tapoulal
- Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre, University of Oxford, Oxford, United Kingdom
| | - Adam J Lewandowski
- Oxford Cardiovascular Clinical Research Facility, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Paul Leeson
- Oxford Cardiovascular Clinical Research Facility, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Neil Herring
- Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre, University of Oxford, Oxford, United Kingdom
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Liao Y, Xu WR, Li HX, Tang CS, Jin HF, Du JB. Plasma Neuropeptide Y Levels in Vasovagal Syncope in Children. Chin Med J (Engl) 2018; 130:2778-2784. [PMID: 29176136 PMCID: PMC5717855 DOI: 10.4103/0366-6999.219157] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Background: Vasovagal syncope (VVS) is the most common cause of syncope in children. Neuropeptide Y (NPY) plays an important role in the regulation of blood pressure (BP), as well as myocardial contractility. This study aimed to explore the role of plasma NPY in VVS in children. Methods: Fifty-six children who were diagnosed with VVS (VVS group) using head-up tilt test (HUT) and 31 healthy children who were selected as controls (control group) were enrolled. Plasma NPY concentrations were detected. The independent t-test was used to compare the data of the VVS group with those of the control group. The changes in plasma NPY levels in the VVS group during the HUT, as well as hemodynamic parameters, such as heart rate (HR), BP, total peripheral vascular resistance (TPVR), and cardiac output (CO), were evaluated using the paired t-test. Furthermore, the correlations between plasma NPY levels and hemodynamic parameters were analyzed using bivariate correlation analysis. Results: The BP, HR, and plasma NPY (0.34 ± 0.12 pg/ml vs. 0.46 ± 0.13 pg/ml) levels in the supine position were statistically low in the VVS group compared to levels in the control group (all P < 0.05). Plasma NPY levels were positively correlated with the HR (Pearson, R = 0.395, P < 0.001) and diastolic BP (Pearson, R = 0.311, P = 0.003) when patients were in the supine position. When patients in the VVS group were in the supine position, elevated TPVR (4.6 ± 3.7 mmHg·min−1·L−1 vs. 2.5 ± 1.0 mmHg·min−1·L−1, respectively, P < 0.001; 1 mmHg = 0.133 kPa) and reduced CO (1.0 ± 0.7 L/min vs. 2.4 ± 1.3 L/min, respectively, P < 0.001) were observed in the positive-response period compared with baseline values. The plasma NPY levels were positively correlated with TPVR (Spearman, R = 0.294, P = 0.028) but negatively correlated with CO in the positive-response period during HUT (Spearman, R = −0.318, P = 0.017). Conclusions: Plasma NPY may contribute to the pathogenesis of VVS by increasing the TPVR and decreasing the CO during orthostatic regulation.
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Affiliation(s)
- Ying Liao
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Wen-Rui Xu
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Hong-Xia Li
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Chao-Shu Tang
- Department of Physiology and Pathophysiology, Health Sciences Centre, Peking University, Beijing 100083, China
| | - Hong-Fang Jin
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Jun-Bao Du
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
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Cheng C, Xu JM, Yu T. Neutralizing IL-6 reduces heart injury by decreasing nerve growth factor precursor in the heart and hypothalamus during rat cardiopulmonary bypass. Life Sci 2017; 178:61-69. [PMID: 28438640 DOI: 10.1016/j.lfs.2017.04.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Revised: 04/10/2017] [Accepted: 04/11/2017] [Indexed: 01/09/2023]
Abstract
AIMS To investigate whether the expression of nerve growth factor precursor (proNGF) changes during cardiopulmonary bypass (CPB) and whether neutralizing interleukin-6 (IL-6) during CPB has cardiac benefits. MAIN METHODS Thirty patients undergoing CPB were recruited and their serum proNGF and troponin-I (TNI) were detected. In addition, rats were divided into three groups: CPB group, CPB with cardiac ischemia-reperfusion (IR) group, and a control group. The pre-CPB standard deviation of N-N intervals (SDNN) and post-CPB SDNN were compared. At the end of CPB, nerve peptide Y (NPY), acetylcholinesterase, cell apoptosis, and proNGF protein expression were measured in the heart and hypothalamus. Another rat cohort undergoing CPB was divided into two groups: an anti-IL-6 group with IL-6 antibody and a control group with phosphate buffer solution. At the end of CPB, serum hs-troponin-T and cardiac caspases 3 and 9 were detected. NPY and proNGF in the heart and hypothalamus were detected. KEY FINDINGS In patients, serum proNGF increased during CPB, and the concentration was positively correlated with TNI. In rats, cardiac autonomic nervous function was disturbed during CPB. More apoptotic cells and higher levels of proNGF were found in the heart and hypothalamus in the CPB groups than in the control groups. Neutralizing IL-6 was beneficial to lower cardiac injury by decreasing proNGF and apoptosis. SIGNIFICANCE CPB induced changes in proNGF in the heart and hypothalamus. Suppressing inflammation attenuated myocardial apoptosis and autonomic nerve function disturbance in CPB rats, likely due in part to regulation of proNGF in the heart and hypothalamus.
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Affiliation(s)
- Chi Cheng
- Department of Anesthesiology, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China
| | - Jun-Mei Xu
- Department of Anesthesiology, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China.
| | - Tian Yu
- Department of Anesthesiology, Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical College, Zunyi, Guizhou 563000, China
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Hallberg M. Neuropeptides: metabolism to bioactive fragments and the pharmacology of their receptors. Med Res Rev 2015; 35:464-519. [PMID: 24894913 DOI: 10.1002/med.21323] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
The proteolytic processing of neuropeptides has an important regulatory function and the peptide fragments resulting from the enzymatic degradation often exert essential physiological roles. The proteolytic processing generates, not only biologically inactive fragments, but also bioactive fragments that modulate or even counteract the response of their parent peptides. Frequently, these peptide fragments interact with receptors that are not recognized by the parent peptides. This review discusses tachykinins, opioid peptides, angiotensins, bradykinins, and neuropeptide Y that are present in the central nervous system and their processing to bioactive degradation products. These well-known neuropeptide systems have been selected since they provide illustrative examples that proteolytic degradation of parent peptides can lead to bioactive metabolites with different biological activities as compared to their parent peptides. For example, substance P, dynorphin A, angiotensin I and II, bradykinin, and neuropeptide Y are all degraded to bioactive fragments with pharmacological profiles that differ considerably from those of the parent peptides. The review discusses a selection of the large number of drug-like molecules that act as agonists or antagonists at receptors of neuropeptides. It focuses in particular on the efforts to identify selective drug-like agonists and antagonists mimicking the effects of the endogenous peptide fragments formed. As exemplified in this review, many common neuropeptides are degraded to a variety of smaller fragments but many of the fragments generated have not yet been examined in detail with regard to their potential biological activities. Since these bioactive fragments contain a small number of amino acid residues, they provide an ideal starting point for the development of drug-like substances with ability to mimic the effects of the degradation products. Thus, these substances could provide a rich source of new pharmaceuticals. However, as discussed herein relatively few examples have so far been disclosed of successful attempts to create bioavailable, drug-like agonists or antagonists, starting from the structure of endogenous peptide fragments and applying procedures relying on stepwise manipulations and simplifications of the peptide structures.
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Affiliation(s)
- Mathias Hallberg
- Beijer Laboratory, Department of Pharmaceutical Biosciences, Division of Biological Research on Drug Dependence, Uppsala University, Biomedical Center, Uppsala, Sweden
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Effects of low-level autonomic stimulation on prevention of atrial fibrillation induced by acute electrical remodeling. ScientificWorldJournal 2013; 2013:781084. [PMID: 23864832 PMCID: PMC3705940 DOI: 10.1155/2013/781084] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Accepted: 06/02/2013] [Indexed: 11/18/2022] Open
Abstract
Background. Rapid atrial pacing (RAP) can induce electrical and autonomic remodeling and facilitate atrial fibrillation (AF). Recent reports showed that low-level vagosympathetic nerve stimulation (LLVNS) can suppress AF, as an antiarrhythmic effect. We hypothesized that LLVNS can reverse substrate heterogeneity induced by RAP. Methods and Results. Mongrel dogs were divided into (LLVNS+RAP) and RAP groups. Electrode catheters were sutured to multiple atrial sites, and LLVNS was applied to cervical vagosympathetic trunks with voltage 50% below the threshold slowing sinus rate by ⩽30 msec. RAP induced a significant decrease in effective refractory period (ERP) and increase in the window of vulnerability at all sites, characterized by descending and elevated gradient differences towards the ganglionic plexi (GP) sites, respectively. The ERP dispersion was obviously enlarged by RAP and more significant when the ERP of GP-related sites was considered. Recovery time from AF was also prolonged significantly as a result of RAP. LLVNS could reverse all these changes induced by RAP and recover the heterogeneous substrate to baseline. Conclusions. LLVNS can reverse the electrical and autonomic remodeling and abolish the GP-central gradient differences induced by RAP, and thus it can recover the homogeneous substrate, which may be the underlying mechanism of its antiarrhythmic effect.
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Yu L, Scherlag BJ, Sha Y, Li S, Sharma T, Nakagawa H, Jackman WM, Lazzara R, Jiang H, Po SS. Interactions between atrial electrical remodeling and autonomic remodeling: how to break the vicious cycle. Heart Rhythm 2011; 9:804-9. [PMID: 22214613 DOI: 10.1016/j.hrthm.2011.12.023] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Indexed: 11/29/2022]
Abstract
BACKGROUND The mechanism(s) underlying the maintenance of atrial fibrillation (AF) during the first few hours after AF was initiated remains poorly understood. OBJECTIVE To investigate the roles of the intrinsic cardiac autonomic nervous system in the maintenance of AF at the early stage. METHODS In 10 anesthetized dogs, we attached multielectrode catheters on atria and pulmonary veins. Microelectrodes inserted into the anterior right ganglionated plexi recorded neural activity. At baseline, programmed stimulation determined the effective refractory period (ERP) and window of vulnerability (WOV), a measure of AF inducibility. For the next 6 hours, AF was simulated by rapid atrial pacing (RAP) and the same parameters were measured hourly during sinus rhythm. A circular catheter was positioned in the superior vena cava for high-frequency stimulation (20 Hz) of the adjacent vagal preganglionics. During 4-6 hours of RAP, we delivered low-level vagal stimulation in the superior vena cava (LL-SVCS), 50% below that which induced slowing of the sinus rate. RESULTS During the 6-hour RAP, there was a progressive decrease in the ERP and an increase in ERP dispersion, WOV, and neural activity. With LL-SVCS during 4-6-hour RAP, ERP, WOV, and neural activity returned toward baseline levels (all P <.05, compared with the third-hour RAP values). CONCLUSIONS RAP not only induces atrial electrical remodeling but also promotes autonomic remodeling. These 2 remodeling processes may form a vicious cycle and each may perpetuate the other. These findings may help to explain how AF maintains itself in its very early stage. LL-SVCS both reversed remodeling processes and can potentially break the vicious cycle of "AF begets AF" in the first few hours of AF.
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Affiliation(s)
- Lilei Yu
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China
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The cardiac sympathetic co-transmitter galanin reduces acetylcholine release and vagal bradycardia: implications for neural control of cardiac excitability. J Mol Cell Cardiol 2011; 52:667-76. [PMID: 22172449 PMCID: PMC3314977 DOI: 10.1016/j.yjmcc.2011.11.016] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Revised: 11/06/2011] [Accepted: 11/28/2011] [Indexed: 02/06/2023]
Abstract
The autonomic phenotype of congestive cardiac failure is characterised by high sympathetic drive and impaired vagal tone, which are independent predictors of mortality. We hypothesize that impaired bradycardia to peripheral vagal stimulation following high-level sympathetic drive is due to sympatho-vagal crosstalk by the adrenergic co-transmitters galanin and neuropeptide-Y (NPY). Moreover we hypothesize that galanin acts similarly to NPY by reducing vagal acetylcholine release via a receptor mediated, protein kinase-dependent pathway. Prolonged right stellate ganglion stimulation (10 Hz, 2 min, in the presence of 10 μM metoprolol) in an isolated guinea pig atrial preparation with dual autonomic innervation leads to a significant (p < 0.05) reduction in the magnitude of vagal bradycardia (5 Hz) maintained over the subsequent 20 min (n = 6). Immunohistochemistry demonstrated the presence of galanin in a small number of tyrosine hydroxylase positive neurons from freshly dissected stellate ganglion tissue sections. Following 3 days of tissue culture however, most stellate neurons expressed galanin. Stellate stimulation caused the release of low levels of galanin and significantly higher levels of NPY into the surrounding perfusate (n = 6, using ELISA). The reduction in vagal bradycardia post sympathetic stimulation was partially reversed by the galanin receptor antagonist M40 after 10 min (1 μM, n = 5), and completely reversed with the NPY Y2 receptor antagonist BIIE 0246 at all time points (1 μM, n = 6). Exogenous galanin (n = 6, 50–500 nM) also reduced the heart rate response to vagal stimulation but had no effect on the response to carbamylcholine that produced similar degrees of bradycardia (n = 6). Galanin (500 nM) also significantly attenuated the release of 3H-acetylcholine from isolated atria during field stimulation (5 Hz, n = 5). The effect of galanin on vagal bradycardia could be abolished by the galanin receptor antagonist M40 (n = 5). Importantly the GalR1 receptor was immunofluorescently co-localised with choline acetyl-transferase containing neurons at the sinoatrial node. The protein kinase C inhibitor calphostin (100 nM, n = 6) abolished the effect of galanin on vagal bradycardia whilst the protein kinase A inhibitor H89 (500 nM, n = 6) had no effect. These results demonstrate that prolonged sympathetic activation releases the slowly diffusing adrenergic co-transmitter galanin in addition to NPY, and that this contributes to the attenuation in vagal bradycardia via a reduction in acetylcholine release. This effect is mediated by GalR1 receptors on vagal neurons coupled to protein kinase C dependent signalling pathways. The role of galanin may become more important following an acute injury response where galanin expression is increased.
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SHA YONG, SCHERLAG BENJAMINJ, YU LILEI, SHENG XIA, JACKMAN WARRENM, LAZZARA RALPH, PO SUNNYS. Low-Level Right Vagal Stimulation: Anticholinergic and Antiadrenergic Effects. J Cardiovasc Electrophysiol 2011; 22:1147-53. [DOI: 10.1111/j.1540-8167.2011.02070.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Protas L, Robinson RB. Dissecting the NPY signaling cascade between cardiac sympathetic and parasympathetic nerves. J Mol Cell Cardiol 2008; 44:470-2. [PMID: 18272171 DOI: 10.1016/j.yjmcc.2008.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2007] [Accepted: 01/02/2008] [Indexed: 01/08/2023]
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Herring N, Lokale MN, Danson EJ, Heaton DA, Paterson DJ. Neuropeptide Y reduces acetylcholine release and vagal bradycardia via a Y2 receptor-mediated, protein kinase C-dependent pathway. J Mol Cell Cardiol 2007; 44:477-85. [PMID: 17996892 DOI: 10.1016/j.yjmcc.2007.10.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Revised: 09/30/2007] [Accepted: 10/01/2007] [Indexed: 12/16/2022]
Abstract
The co-transmitter neuropeptide Y (NPY), released during prolonged cardiac sympathetic nerve stimulation, can attenuate vagal-induced bradycardia. We tested the hypothesis that NPY reduces acetylcholine release, at similar concentrations to which it attenuates vagal bradycardia, via pre-synaptic Y2 receptors modulating a pathway that is dependent on protein kinase A (PKA) or protein kinase C (PKC). The Y2 receptor was immunofluorescently colocalized with choline acetyl-transferase containing neurons at the guinea pig sinoatrial node. The effect of NPY in the presence of various enzyme inhibitors was then tested on the heart rate response to vagal nerve stimulation in isolated guinea pig sinoatrial node/right vagal nerve preparations and also on (3)H-acetylcholine release from right atria during field stimulation. NPY reduced the heart rate response to vagal stimulation at 1, 3 and 5 Hz (significant at 100 nM and reaching a plateau at 250 nM NPY, p<0.05, n=6) but not to the stable analogue of acetylcholine, carbamylcholine (30, 60 or 90 nM, n=6) which produced similar degrees of bradycardia. The reduced vagal response was abolished by the Y2 receptor antagonist BIIE 0246 (1 microM, n=4). NPY also significantly attenuated the release of (3)H-acetylcholine during field stimulation (250 nM, n=6). The effect of NPY (250 nM) on vagal bradycardia was abolished by the PKC inhibitors calphostin C (0.1 microM, n=5) and chelerythrine chloride (25 microM, n=6) but not the PKA inhibitor H89 (0.5 microM, n=6). Conversely, the PKC activator Phorbol-12-myristate-13-acetate (0.5 microM, n=7) mimicked the effect of NPY and significantly reduced (3)H-acetylcholine release during field stimulation. These results show that NPY attenuates vagal bradycardia via a pre-synaptic decrease in acetylcholine release that appears to be mediated by a Y2 receptor pathway involving modulation of PKC.
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Affiliation(s)
- Neil Herring
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Parks Road, Oxford University OX1 3PT, UK
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Ilebekk A, Eriksen M, Sevre K, Aspelin T, Björkman JA, Lyberg T, Nordlander M. Ventricular fibrillation induced by ischemia-reperfusion is not prevented by the NPY Y2 receptor antagonist BIIE0246. J Cardiovasc Pharmacol Ther 2007; 11:177-83. [PMID: 17056830 DOI: 10.1177/1074248406292709] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Neuropeptide Y is released together with norepinephrine from sympathetic nerve terminals during conditions of increased sympathetic activity. Neuropeptide Y is known to inhibit vagal activity, and accordingly, it might increase the risk for ventricular fibrillation during myocardial ischemia-reperfusion, with concomitant sympathetic stimulation. Counteracting the inhibiting effect of neuropeptide Y by the specific neuropeptide Y2 antagonist, BIIE0246, we expected occurrence of ventricular fibrillation in association with repeated periods of myocardial ischemia-reperfusion to decrease. The midleft anterior descending coronary artery was repeatedly occluded in 16 open-chest pigs. Eight pigs received BIIE0246, and the controls received the vehicle only. Ventricular fibrillation developed in 2 animals of the control group, but in 4 pigs receiving BIIE0246. Occurrence of ventricular fibrillation and ventricular tachycardia did not differ significantly between the 2 groups, and in association with repeated periods of regional myocardial ischemia, did not decline in pigs treated by the specific neuropeptide Y2-receptor antagonist BIIE0246.
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Affiliation(s)
- Arnfinn Ilebekk
- Institute for Experimental Medical Research, University of Oslo, Oslo, Norway.
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