1
|
Guevara A, Smith CER, Caldwell JL, Ngo L, Mott LR, Lee IJ, Tapa S, Wang Z, Wang L, Woodward WR, Ng GA, Habecker BA, Ripplinger CM. Chronic nicotine exposure is associated with electrophysiological and sympathetic remodeling in the intact rabbit heart. Am J Physiol Heart Circ Physiol 2024; 326:H1337-H1349. [PMID: 38551482 DOI: 10.1152/ajpheart.00749.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 03/27/2024] [Accepted: 03/27/2024] [Indexed: 04/09/2024]
Abstract
Nicotine is the primary addictive component of tobacco products. Through its actions on the heart and autonomic nervous system, nicotine exposure is associated with electrophysiological changes and increased arrhythmia susceptibility. To assess the underlying mechanisms, we treated rabbits with transdermal nicotine (NIC, 21 mg/day) or control (CT) patches for 28 days before performing dual optical mapping of transmembrane potential (RH237) and intracellular Ca2+ (Rhod-2 AM) in isolated hearts with intact sympathetic innervation. Sympathetic nerve stimulation (SNS) was performed at the first to third thoracic vertebrae, and β-adrenergic responsiveness was additionally evaluated following norepinephrine (NE) perfusion. Baseline ex vivo heart rate (HR) and SNS stimulation threshold were higher in NIC versus CT (P = 0.004 and P = 0.003, respectively). Action potential duration alternans emerged at longer pacing cycle lengths (PCL) in NIC versus CT at baseline (P = 0.002) and during SNS (P = 0.0003), with similar results obtained for Ca2+ transient alternans. SNS shortened the PCL at which alternans emerged in CT but not in NIC hearts. NIC-exposed hearts tended to have slower and reduced HR responses to NE perfusion, but ventricular responses to NE were comparable between groups. Although fibrosis was unaltered, NIC hearts had lower sympathetic nerve density (P = 0.03) but no difference in NE content versus CT. These results suggest both sympathetic hypoinnervation of the myocardium and regional differences in β-adrenergic responsiveness with NIC. This autonomic remodeling may contribute to the increased risk of arrhythmias associated with nicotine exposure, which may be further exacerbated with long-term use.NEW & NOTEWORTHY Here, we show that chronic nicotine exposure was associated with increased heart rate, increased susceptibility to alternans, and reduced sympathetic electrophysiological responses in the intact rabbit heart. We suggest that this was due to sympathetic hypoinnervation of the myocardium and diminished β-adrenergic responsiveness of the sinoatrial node following nicotine treatment. Though these differences did not result in increased arrhythmia propensity in our study, we hypothesize that prolonged nicotine exposure may exacerbate this proarrhythmic remodeling.
Collapse
Affiliation(s)
- Amanda Guevara
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Charlotte E R Smith
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Jessica L Caldwell
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Lena Ngo
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Lilian R Mott
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - I-Ju Lee
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Srinivas Tapa
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Zhen Wang
- Department of Pharmacology, University of California Davis, Davis, California, United States
- Shantou University Medical College, Shantou, People's Republic of China
| | - Lianguo Wang
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - William R Woodward
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, Oregon, United States
| | - G Andre Ng
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- National Institute for Health and Care Research, Leicester Biomedical Research Centre, Leicester, United Kingdom
- Glenfield Hospital, Leicester, United Kingdom
| | - Beth A Habecker
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, Oregon, United States
- Department of Medicine and Knight Cardiovascular Institute, Oregon Health and Science University, Portland, Oregon, United States
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California Davis, Davis, California, United States
| |
Collapse
|
2
|
Guevara A, Smith CER, Caldwell JL, Ngo L, Mott LR, Lee IJ, Tapa I, Wang Z, Wang L, Woodward WR, Ng GA, Habecker BA, Ripplinger CM. Chronic nicotine exposure is associated with electrophysiological and sympathetic remodeling in the intact rabbit heart. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.23.567754. [PMID: 38045290 PMCID: PMC10690259 DOI: 10.1101/2023.11.23.567754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Nicotine is the primary addictive component in tobacco products. Through its actions on the heart and autonomic nervous system, nicotine exposure is associated with electrophysiological changes and increased arrhythmia susceptibility. However, the underlying mechanisms are unclear. To address this, we treated rabbits with transdermal nicotine (NIC, 21 mg/day) or control (CT) patches for 28 days prior to performing dual optical mapping of transmembrane potential (RH237) and intracellular Ca 2+ (Rhod-2 AM) in isolated hearts with intact sympathetic innervation. Sympathetic nerve stimulation (SNS) was performed at the 1 st - 3 rd thoracic vertebrae, and β-adrenergic responsiveness was additionally evaluated as changes in heart rate (HR) following norepinephrine (NE) perfusion. Baseline ex vivo HR and SNS stimulation threshold were increased in NIC vs. CT ( P = 0.004 and P = 0.003 respectively). Action potential duration alternans emerged at longer pacing cycle lengths (PCL) in NIC vs. CT at baseline ( P = 0.002) and during SNS ( P = 0.0003), with similar results obtained for Ca 2+ transient alternans. SNS reduced the PCL at which alternans emerged in CT but not NIC hearts. NIC exposed hearts also tended to have slower and reduced HR responses to NE perfusion. While fibrosis was unaltered, NIC hearts had lower sympathetic nerve density ( P = 0.03) but no difference in NE content vs. CT. These results suggest both sympathetic hypo-innervation of the myocardium and diminished β-adrenergic responsiveness with NIC. This autonomic remodeling may underlie the increased risk of arrhythmias associated with nicotine exposure, which may be further exacerbated with continued long-term usage. NEW & NOTEWORTHY Here we show that chronic nicotine exposure was associated with increased heart rate, lower threshold for alternans and reduced sympathetic electrophysiological responses in the intact rabbit heart. We suggest that this was due to the sympathetic hypo-innervation of the myocardium and diminished β- adrenergic responsiveness observed following nicotine treatment. Though these differences did not result in increased arrhythmia propensity in our study, we hypothesize that prolonged nicotine exposure may exacerbate this pro-arrhythmic remodeling.
Collapse
|
3
|
Lee SH, Kim BJ, Kang J, Seo DC, Lee SJ. Association of Self-Reported and Cotinine-Verified Smoking Status with Atrial Arrhythmia. J Korean Med Sci 2020; 35:e296. [PMID: 32864907 PMCID: PMC7458848 DOI: 10.3346/jkms.2020.35.e296] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 07/12/2020] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND The relationship between self-reported and urinary cotinine-verified smoking status and atrial arrhythmia (AA) is unclear. The aim of this study was to evaluate the association of self-reported and urine cotinine-verified smoking status with AA. METHOD A total of 201,788 participants (106,375 men, mean age 37 years) who had both a urinary cotinine measurement and electrocardiogram were included. Cotinine-verified current smoking was defined as a urinary cotinine level above 50 ng/mL. Individuals were divided into three groups based on self-reported smoking and two groups based on cotinine-verified smoking status. RESULTS Among overall subjects, 505 had documented AA (0.3%) and 135 had atrial fibrillation (AF) (0.1%). Self-reported current smoking was associated with an increased risk of AA (odds ratio [OR], 1.42; 95% confidence interval [CI], 1.06-1.91; P = 0.019) and AF (OR, 2.20; 95% CI, 1.24-3.90; P = 0.007), whereas self-reported former smoking had no significant association with AA (OR, 1.30; 95% CI, 0.97-1.73; P = 0.078) and AF (OR, 1.74; 95% CI, 1.00-3.04; P = 0.051). Cotinine-verified current smoking showed no significant association with AA (OR, 1.24; 95% CI, 0.98-1.58; P = 0.080) and AF (OR, 1.20; 95% CI, 0.79-1.83; P = 0.391). CONCLUSION Self-reported current smoking was associated with AA and AF, while self-reported former smoking and cotinine-verified current smoking showed no significant association with AA and AF.
Collapse
Affiliation(s)
- Sung Ho Lee
- Division of Cardiology, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Byung Jin Kim
- Division of Cardiology, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
| | - Jeonggyu Kang
- Center for Cohort Studies, Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Dae Chul Seo
- Division of Cardiology, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Seung Jae Lee
- Division of Cardiology, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| |
Collapse
|
4
|
Jalili C, Salahshoor MR, Moradi MT, Ahookhash M, Taghadosi M, Sohrabi M. Expression Changes of Apoptotic Genes in Tissues from Mice Exposed to Nicotine. Asian Pac J Cancer Prev 2017; 18:239-244. [PMID: 28240526 PMCID: PMC5563107 DOI: 10.22034/apjcp.2017.18.1.239] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Objective: Smoking is the leading preventable cause of various diseases such as lung cancer, chronic obstructive pulmonary disease and cardiovascular disease. Nicotine, one of the major toxic components of tobacco, contributes to the pathogenesis of different diseases. Methods: Given the controversy about nicotine toxicity, the present study was conducted to determine apoptotic effects of nicotine on the heart, kidney, lung and liver of male mice. Real-time PCR was performed to identify mRNA expression changes in apoptotic-related genes between nicotine treated and control mice. Result: In the heart and lung, nicotine caused significant decrease in P53, Bax and Caspase-3 mRNA expression levels compared to the control group. However, in the kidney and liver, the result was significant increase in Bax, Caspase-2, Caspase-3 and a significant decrease in P53 mRNA expression (p<0.01). DNA fragmentation assays indicated no fragmentation in the heart and lung, but in the kidney and liver of nicotine treated mice, isolated DNA was fragmented. Conclusion: Our study provided insight into the molecular mechanisms of nicotine anti-apoptotic effects on the heart and lung as well as pro-apoptotic effects on kidney and liver via a P53-independent pathway.
Collapse
Affiliation(s)
- Cyrus Jalili
- Fertility and Infertility Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran.
| | | | | | | | | | | |
Collapse
|
5
|
Joukar S, Sheibani V, Koushesh F, Ghasemipoor Afshar E, Ghorbani Shahrbabaki S. Arrhythmogenic Risk Assessment Following Four-Week Pretreatment With Nicotine and Black Tea in Rat. Res Cardiovasc Med 2015; 4:e27088. [PMID: 26436072 PMCID: PMC4588709 DOI: 10.5812/cardiovascmed.27088v2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2015] [Revised: 03/10/2015] [Accepted: 03/16/2015] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND There is the controversy concerning the main component of tobacco, which is responsible for its arrhythmogenesis. In addition, there is the lack of adequate information about the influence of combination of black tea and nicotine on heart rhythm. OBJECTIVES This study aimed to examine whether pretreatment with black tea and nicotine could modulate the susceptibility to lethal ventricular arrhythmias. MATERIALS AND METHODS Animals were randomized to control, black tea, nicotine, and black tea plus nicotine groups. Test groups were treated with black tea brewed (orally) and nicotine (2 mg/kg, subcutaneous), alone and in combination for four weeks. On day 29, aconitine was infused intravenously for induction of cardiac arrhythmia. RESULTS In comparison with the control group, each of tea and nicotine significantly decreased the duration of the ventricular tachycardia (VT) plus ventricular fibrillation (VF) and the score of arrhythmia severity (P < 0.05 and P < 0.01, respectively,). The latency for the first VT event was significantly longer in the all test groups, but VF latency was significant only in tea and nicotine groups compared with control group (P < 0.05 and P < 0.01, respectively).Threshold dose of aconitine for inducing VT and VF increased in all test groups, but only VT showed a significant difference in comparison to the control group (P < 0.001). CONCLUSIONS The findings suggest that sub-chronic consumption of nicotine or black tea alone with appropriate doses could potentially be antiarrhythmic and its combination regimen does not increase the risk of fatal ventricular arrhythmias during four-week consumption period in rats.
Collapse
Affiliation(s)
- Siyavash Joukar
- Physiology Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, IR Iran
- Neuroscience Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, IR Iran
- Department of Physiology and Pharmacology, Kerman University of Medical Sciences, Kerman, IR Iran
- Corresponding author: Siyavash Joukar, Department of Physiology, Physiology Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, IR Iran. Tel/Fax: +98-3413220081, E-mail:
| | - Vahid Sheibani
- Neuroscience Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, IR Iran
- Department of Physiology and Pharmacology, Kerman University of Medical Sciences, Kerman, IR Iran
| | - Faramarz Koushesh
- School of Allied Medical Sciences, Bushehr University of Medical Sciences, Bushehr, IR Iran
| | - Elham Ghasemipoor Afshar
- Physiology Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, IR Iran
- Department of Physiology and Pharmacology, Kerman University of Medical Sciences, Kerman, IR Iran
| | - Soodabe Ghorbani Shahrbabaki
- Physiology Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, IR Iran
| |
Collapse
|
6
|
Hu N, Ren J. Nicotine, cigarette smoking and cardiac function: an update. Toxicol Res (Camb) 2014. [DOI: 10.1039/c3tx50044f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
|
7
|
Wang L, Li X, Zhou Y, Shi H, Xu C, He H, Wang S, Xiong X, Zhang Y, Du Z, Zhang R, Lu Y, Yang B, Shan H. Downregulation of miR-133 via MAPK/ERK signaling pathway involved in nicotine-induced cardiomyocyte apoptosis. Naunyn Schmiedebergs Arch Pharmacol 2013; 387:197-206. [PMID: 24190542 DOI: 10.1007/s00210-013-0929-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2013] [Accepted: 10/09/2013] [Indexed: 12/30/2022]
Abstract
Tobacco smoking is a risk factor for many diseases, and nicotine is a major component of tobacco. Our previous work revealed that nicotine can induce myocardial fibrosis. This study aimed to investigate whether nicotine can induce cardiomyocyte apoptosis and to explore the mechanisms involved. Cardiomyocytes were exposed to different nicotine concentrations for 48 h. MTT assay showed that the viability of cardiomyocytes was significantly inhibited by nicotine in a dose- and time-dependent manner. Loss of mitochondrial membrane potential, nuclear and DNA defragmentation determined by TUNEL and ELISA assays, and morphological alterations all revealed the pro-apoptotic property of nicotine. Meanwhile, miR-133, a muscle-specific microRNA, was markedly downregulated by nicotine. Consistently, caspase-9, a target gene for miR-133, was significantly upregulated, leading to an increase in caspase-3, in nicotine-treated cardiomyocytes compared to non-treated cells. Furthermore, ERK1/2 protein levels were considerably downregulated, along with reduction of serum response factor (SRF), which is a downstream target protein of ERK1/2 and an upstream transactivator of miR-133 as well. Our findings therefore revealed that inhibition of the ERK1/2-SRF-miR-133 signaling pathway to increase caspases-9 and -3 is a novel mechanism for nicotine to induce cardiomyocyte apoptosis and these tobacco smokers.
Collapse
Affiliation(s)
- Lu Wang
- Department of Pharmacology (the State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), Harbin Medical University, No.157 Baojian Road, Harbin, Heilongjiang Province, 150081, People's Republic of China
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Visweswaran R, McIntyre SD, Ramkrishnan K, Zhao X, Tolkacheva EG. Spatiotemporal evolution and prediction of [Ca(2+) ]i and APD alternans in isolated rabbit hearts. J Cardiovasc Electrophysiol 2013; 24:1287-95. [PMID: 23845004 DOI: 10.1111/jce.12200] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 05/17/2013] [Accepted: 05/28/2013] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Action potential duration (APD) alternans can be accompanied by alternans in intracellular calcium transients ([Ca(2+) ]i ), leading to electromechanical alternans. Electromechanical alternans is considered a substrate for ventricular fibrillation. Although some techniques have been developed to predict APD alternans, the onset of [Ca(2+) ]i alternans has never been predicted. METHODS AND RESULTS Simultaneous mapping of voltage and calcium was performed in 8 Langendorff-perfused rabbit hearts. APD, [Ca(2+) ]i amplitude (CaA) and duration (CaD) alternans were induced using a perturbed downsweep protocol. Local onset of alternans (B(onset) ) was defined as the cycle length (BCL) at which at least 10% of the RV exhibited alternans. We observed that the local onset of CaA alternans always occurred first, followed by APD and then CaD alternans. We constructed APD, CaD, and CaA restitution portraits for 2 regions of the heart defined at B(onset) : the 1:1alt region, which developed alternans, and the 1:1 region, which did not. Our results also show that the slopes S12 Max and SDyn were higher in 1:1alt region (SDyn = 0.99 ± 0.04 vs 0.73 ± 0.06; S12 Max = 0.95 ± 0.13 vs 0.65 ± 0.1, P < 0.05) prior to onset of CaD alternans, while S12 and S12 Max were significantly higher in the 1:1alt region (S12 = 0.59 ± 0.19 vs 0.19 ± 0.02; S12 Max = 1.09 ± 0.1 vs 0.61 ± 0.08, P < 0.05) prior to onset of CaA alternans. CONCLUSION We successfully applied the restitution portrait technique to the prediction of [Ca(2+) ]i (both CaA and CaD) alternans. The slopes of the APD/CaD/CaA restitution portrait are definitive indicators of APD, CaD, and CaA alternans.
Collapse
|
9
|
D'Alessandro A, Boeckelmann I, Hammwhöner M, Goette A. Nicotine, cigarette smoking and cardiac arrhythmia: an overview. Eur J Prev Cardiol 2012; 19:297-305. [PMID: 22779085 DOI: 10.1177/1741826711411738] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Tobacco smoke is the single most important modifiable risk factor for coronary diseases and the leading preventable cause of death in the US. While the effect of cigarette smoking on the progression of atherosclerotic diseases is established and well studied, the role of cigarette smoking on cardiac arrhythmia is less clearly defined. In fact the pathophysiological mechanism of cigarette smoking-induced cardiac arrhythmia is very likely a complex one where the pro-fibrotic effect of nicotine on myocardial tissue with consequent increased susceptibility to catecholamine might play a role. Moreover, other constituents of cigarette smoking, such as carbon monoxide and oxidative stress, are likely to contribute to the generation of arrhythmias. Finally, cigarette smoking may induce coronary artery disease and chronic obstructive pulmonary disease, which also might cause arrhythmia independently. The objective of this paper is to summarize the published studies relating to cardiac arrhythmia induced by cigarette smoking, and to identify a pathophysiological mechanism by which cigarette smoking might induce cardiac arrhythmia.
Collapse
Affiliation(s)
- Alessandra D'Alessandro
- Section of Occupational Medicine,Otto von Guericke University of Magdeburg, Leipziger Strasse 44, Magdeburg, Germany.
| | | | | | | |
Collapse
|
10
|
Akturk E, Yağmur J, Açıkgöz N, Ermiş N, Cansel M, Karakuş Y, Taşolar H, Eyupkoca F, Pekdemir H. Assessment of atrial conduction time by tissue Doppler echocardiography and P-wave dispersion in smokers. J Interv Card Electrophysiol 2012; 34:247-53. [PMID: 22391961 DOI: 10.1007/s10840-011-9658-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Accepted: 12/28/2011] [Indexed: 12/01/2022]
Abstract
INTRODUCTION The aim of this study was to evaluate the relationship between cigarette smoking and atrial rhythm disorders with the use of noninvasive methods. METHODS The study population consisted of 50 healthy volunteer smokers and 40 healthy volunteer non-smokers who had normal echocardiographic parameters and similar sex and age profiles. P-wave dispersion (PWD) was calculated from the 12-lead surface ECG. Left ventricle (LV) end-systolic and end-diastolic diameters, LV ejection fraction, and interatrial and intraatrial electromechanical delay were measured by tissue Doppler imaging and conventional echocardiography. RESULTS Isovolumetric relaxation time and deceleration time were significantly higher (91.5 ± 11 vs. 82.35 ± 8.6, p < 0.0001; 215.7 ± 37.1 vs. 175.3 ± 17.7, p < 0.0001, respectively), and HDL cholesterol was significantly lower in smokers (39.34 ± 7.5 vs.44.3 ± 8.07, p = 0.003). There were no significant differences between the groups with respect to Sm and Em values, Am value, and E/A and E/Em ratios. However, the Em/Am ratio was significantly lower in smokers (1.28 ± 0.21 vs. 1.44 ± 0.33, p < 0.006). Inter- and intraatrial electromechanical delay were significantly higher in smokers when compared with non-smokers (51.11 ± 1.54 vs. 27.30 ± 3.36, p < 0.0001, and 30.63 ± 3.2 vs. 12.24 ± 3.26, p < 0.0001, respectively). The amount of smoking was strongly correlated with interatrial electromechanical delay (r = 0.567, p < 0.0001), and a significant correlation was detected between PWD and interatrial electromechanical delay (r = 0.653, p = 0.001). CONCLUSION We have demonstrated the relationship between inter- and intraatrial electromechanical delay and PWD. These parameters may be useful predictive markers for the development of AF in the asymptomatic period before cardiac rhythm disturbances occur. This finding may indicate that smokers have an increased risk of developing atrial rhythm disturbances.
Collapse
Affiliation(s)
- Erdal Akturk
- Cardiology Department, Adıyaman University, Adiyaman, Turkey.
| | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Gaffin RD, Chowdhury SAK, Alves MSL, Dias FAL, Ribeiro CTD, Fogaca RTH, Wieczorek DF, Wolska BM. Effects of nicotine administration in a mouse model of familial hypertrophic cardiomyopathy, α-tropomyosin D175N. Am J Physiol Heart Circ Physiol 2011; 301:H1646-55. [PMID: 21743000 DOI: 10.1152/ajpheart.00277.2010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The effects of nicotine (NIC) on normal hearts are fairly well established, yet its effects on hearts displaying familial hypertrophic cardiomyopathy have not been tested. We studied both the acute and chronic effects of NIC on a transgenic (TG) mouse model of FHC caused by a mutation in α-tropomyosin (Tm; i.e., α-Tm D175N TG, or Tm175). For acute effects, intravenously injected NIC increased heart rate, left ventricular (LV) pressure, and the maximal rate of LV pressure increase (+dP/dt) in non-TG (NTG) and Tm175 mice; however, Tm175 showed a significantly smaller increase in the maximal rate of LV pressure decrease (-dP/dt) compared with NTGs. Western blots revealed phosphorylation of phospholamban Ser16 and Thr17 residue increased in NTG mice following NIC injection but not in Tm175 mice. In contrast, phosphorylation of troponin I at serine residues 23 and 24 increased equally in both NTG and Tm175. Thus the attenuated increase in relaxation in Tm175 mice following acute NIC appears to result primarily from attenuated phospholamban phosphorylation. Chronic NIC administration (equivalent to smoking 2 packs of cigarettes/day for 4 mo) also increased +dP/dt in NTG and Tm175 mice compared with chronic saline. However, chronic NIC had little effect on heart rate, LV pressure, -dP/dt, LV wall and chamber dimensions, or collagen content for either group of mice.
Collapse
Affiliation(s)
- Robert D Gaffin
- Department of Physiology and Biophysics, Section of Cardiology, Center for Cardiovascular Research, University of Illinois at Chicago, Chicago, Illinois 60612, USA
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Morita N, Lee JH, Bapat A, Fishbein MC, Mandel WJ, Chen PS, Weiss JN, Karagueuzian HS. Glycolytic inhibition causes spontaneous ventricular fibrillation in aged hearts. Am J Physiol Heart Circ Physiol 2011; 301:H180-91. [PMID: 21478408 DOI: 10.1152/ajpheart.00128.2011] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Selective glycolytic inhibition (GI) promotes electromechanical alternans and triggered beats in isolated cardiac myocytes. We sought to determine whether GI promotes triggered activity by early afterdepolarization (EAD) or delayed afterdepolarizations in intact hearts isolated from adult and aged rats. Dual voltage and intracellular calcium ion (Ca(i)(2+)) fluorescent optical maps and single cell glass microelectrode recordings were made from the left ventricular (LV) epicardium of isolated Langendorff-perfused adult (∼4 mo) and aged (∼24 mo) rat hearts. GI was induced by replacing glucose with 10 mM pyruvate in oxygenated Tyrode's. Within 20 min, GI slowed Ca(i)(2+) transient decline rate and shortened action potential duration in both groups. These changes were associated with ventricular fibrillation (VF) in the aged hearts (64 out of 66) but not in adult hearts (0 out of 18; P < 0.001). VF was preceded by a transient period of focal ventricular tachycardia caused by EAD-mediated triggered activity leading to VF within seconds. The VF was suppressed by the ATP-sensitive K (K(ATP)) channel blocker glibenclamide (1 μM) but not (0 out of 7) by mitochondrial K(ATP) block. The Ca-calmodulin-dependent protein kinase II (CaMKII) blocker KN-93 (1 μM) prevented GI-mediated VF (P < 0.05). Block of Na-Ca exchanger (NCX) by SEA0400 (2 μM) prevented GI-mediated VF (3 out of 6), provided significant bradycardia did not occur. Aged hearts had significantly greater LV fibrosis and reduced connexin 43 than adult hearts (P < 0.05). We conclude that in aged fibrotic unlike in adult rat hearts, GI promotes EADs, triggered activity, and VF by activation of K(ATP) channels CaMKII and NCX.
Collapse
Affiliation(s)
- Norishige Morita
- Translational Arrhythmia Research Section, Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, 675 Charles E. Young Dr. South, MRL 3645 Mail Code: 176022, Los Angeles, CA 90095, USA
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Cardiac-specific overexpression of metallothionein rescues nicotine-induced cardiac contractile dysfunction and interstitial fibrosis. Toxicol Lett 2011; 202:8-14. [PMID: 21238558 DOI: 10.1016/j.toxlet.2011.01.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Revised: 01/07/2011] [Accepted: 01/07/2011] [Indexed: 11/22/2022]
Abstract
Cigarette smoking is a devastating risk factor for cardiovascular diseases and nicotine is believed the main toxin component responsible for the toxic myocardial effects of smoking. Nonetheless, neither the precise mechanism of nicotine-induced cardiac dysfunction nor effective treatment is elucidated. The aim of this study was to evaluate the impact of cardiac-specific overexpression of heavy metal scavenger metallothionein on myocardial geometry and mechanical function following nicotine exposure. Adult male friend virus B (FVB) wild-type and metallothionein mice were injected with nicotine (2 mg/kg/d) intraperitoneally for 10 days. Mechanical and intracellular Ca²+ properties were examined. Myocardial histology (cross-sectional area and fibrosis) was evaluated by hematoxylin and eosin (H&E) and Masson trichrome staining, respectively. Oxidative stress and apoptosis were measured by fluoroprobe 5-(6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate (CM-H₂DCFDA) fluorescence and caspase-3 activity, respectively. Nicotine exposure failed to affect the protein abundance of metallothionein. Our data revealed reduced echocardiographic contractile capacity (fractional shortening), altered cardiomyocyte contractile and intracellular Ca²+ properties including depressed peak shortening amplitude, maximal velocity of shortening/relengthening, resting and electrically-stimulated rise in intracellular Ca²+, as well as prolonged duration of relengthening and intracellular Ca²+ clearance in hearts from nicotine-treated FVB mice, the effect of which was ameliorated by metallothionein. Biochemical and histological findings depicted overt accumulation of reactive oxygen species (ROS), apoptosis and myocardial fibrosis without any change in myocardial cross-sectional area following nicotine treatment, which was mitigated by metallothionein. Taken together, our findings suggest the antioxidant metallothionein may reconcile short-term nicotine exposure-induced myocardial contractile dysfunction and fibrosis possibly through inhibition of ROS accumulation and apoptosis.
Collapse
|
14
|
Abstract
Interstitial and perivascular fibrosis is a hallmark of adverse cardiac remodeling in response to stress such as hypertension, valve disease, or myocardial infarction. The cross talk between fibroblasts and cardiomyocytes seems to be a major determinant of the hypertrophic response, and fibroblasts may prove to be essential regulators of cardiac remodeling. The present review summarizes current knowledge on the modulation of myocardial fibrosis by microRNAs (miRNAs), single-stranded molecules consisting of approximately 22 noncoding nucleotides that regulate a variety of target genes involved in cardiovascular (patho)physiology. Dissection of miRNA-mediated mechanisms on myocardial and cellular and subcellular levels will provide insights into the impact of miRNAs for cardiac structural changes induced by different stressors and also expand our understanding of the interdependence of different cell types in the heart with regard to extracellular matrix formation during healing and remodeling after myocardial infarction or in response to pressure overload. The first successful treatment of fibrosis and failure in a murine pressure overload model by application of miRNA antagonists such as antagomirs in vivo raises the hope that manipulating miRNAs may emerge as a novel treatment strategy for fibrotic changes not only in the heart but also in other organs.
Collapse
Affiliation(s)
- Johann Bauersachs
- Medizinische Klinik und Poliklinik I, Universitätsklinikum, Julius-Maximilians-Universität, Würzburg, Germany.
| |
Collapse
|
15
|
Morita N, Sovari AA, Xie Y, Fishbein MC, Mandel WJ, Garfinkel A, Lin SF, Chen PS, Xie LH, Chen F, Qu Z, Weiss JN, Karagueuzian HS. Increased susceptibility of aged hearts to ventricular fibrillation during oxidative stress. Am J Physiol Heart Circ Physiol 2009; 297:H1594-605. [PMID: 19767530 DOI: 10.1152/ajpheart.00579.2009] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Oxidative stress with hydrogen peroxide (H(2)O(2)) readily promotes early afterdepolarizations (EADs) and triggered activity (TA) in isolated rat and rabbit ventricular myocytes. Here we examined the effects of H(2)O(2) on arrhythmias in intact Langendorff rat and rabbit hearts using dual-membrane voltage and intracellular calcium optical mapping and glass microelectrode recordings. Young adult rat (3-5 mo, N = 25) and rabbit (3-5 mo, N = 6) hearts exhibited no arrhythmias when perfused with H(2)O(2) (0.1-2 mM) for up to 3 h. However, in 33 out of 35 (94%) aged (24-26 mo) rat hearts, 0.1 mM H(2)O(2) caused EAD-mediated TA, leading to ventricular tachycardia (VT) and fibrillation (VF). Aged rabbits (life span, 8-12 yr) were not available, but 4 of 10 middle-aged rabbits (3-5 yr) developed EADs, TA, VT, and VF. These arrhythmias were suppressed by the reducing agent N-acetylcysteine (2 mM) and CaMKII inhibitor KN-93 (1 microM) but not by its inactive form (KN-92, 1 microM). There were no significant differences between action potential duration (APD) or APD restitution slope before or after H(2)O(2) in aged or young adult rat hearts. In histological sections, however, trichrome staining revealed that aged rat hearts exhibited extensive fibrosis, ranging from 10-90%; middle-aged rabbit hearts had less fibrosis (5-35%), whereas young adult rat and rabbit hearts had <4% fibrosis. In aged rat hearts, EADs and TA arose most frequently (70%) from the left ventricular base where fibrosis was intermediate ( approximately 30%). Computer simulations in two-dimensional tissue incorporating variable degrees of fibrosis showed that intermediate (but not mild or severe) fibrosis promoted EADs and TA. We conclude that in aged ventricles exposed to oxidative stress, fibrosis facilitates the ability of cellular EADs to emerge and generate TA, VT, and VF at the tissue level.
Collapse
Affiliation(s)
- Norishige Morita
- Translational Arrhythmia Research Laboratory and Cardiovascular Research Laboratory, Division of Cardiology, Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Shan H, Zhang Y, Lu Y, Zhang Y, Pan Z, Cai B, Wang N, Li X, Feng T, Hong Y, Yang B. Downregulation of miR-133 and miR-590 contributes to nicotine-induced atrial remodelling in canines. Cardiovasc Res 2009; 83:465-72. [PMID: 19398468 DOI: 10.1093/cvr/cvp130] [Citation(s) in RCA: 263] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
AIMS The present study was designed to decipher molecular mechanisms underlying nicotine's promoting atrial fibrillation (AF) by inducing atrial structural remodelling. METHODS AND RESULTS The canine model of AF was successfully established by nicotine administration and rapid pacing. The atrial fibroblasts isolated from healthy dogs were treated with nicotine. The role of microRNAs (miRNAs) on the expression and regulation of transforming growth factor-beta1 (TGF-beta1), TGF-beta receptor type II (TGF-betaRII), and collagen production was evaluated in vivo and in vitro. Administration of nicotine for 30 days increased AF vulnerability by approximately eight- to 15-fold in dogs. Nicotine stimulated remarkable collagen production and atrial fibrosis both in vitro in cultured canine atrial fibroblasts and in vivo in atrial tissues. Nicotine produced significant upregulation of expression of TGF-beta1 and TGF-betaRII at the protein level, and a 60-70% decrease in the levels of miRNAs miR-133 and miR-590. This downregulation of miR-133 and miR-590 partly accounts for the upregulation of TGF-beta1 and TGF-betaRII, because our data established TGF-beta1 and TGF-betaRII as targets for miR-133 and miR-590 repression. Transfection of miR-133 or miR-590 into cultured atrial fibroblasts decreased TGF-beta1 and TGF-betaRII levels and collagen content. These effects were abolished by the antisense oligonucleotides against miR-133 or miR-590. The effects of nicotine were prevented by an alpha7 nicotinic acetylcholine receptor antagonist. CONCLUSION We conclude that the profibrotic response to nicotine in canine atrium is critically dependent upon downregulation of miR-133 and miR-590.
Collapse
Affiliation(s)
- Hongli Shan
- Department of Pharmacology, State-Province Key Laboratories of Biomedicine and Pharmaceutics, Harbin, Heilongjiang 150081, PR China
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
TUAN TACHUAN, CHANG SHIHLIN, TAI CHINGTAI, LIN YENNJIANG, HU YUFENG, LO LIWEI, WONGCHAROEN WANWARANG, UDYAVAR AMEYAR, CHIANG SHUOJU, CHEN YIJEN, TSAO HSUANMING, UENG KWOCHANG, CHEN SHIHANN. Impairment of the Atrial Substrates by Chronic Cigarette Smoking in Patients with Atrial Fibrillation. J Cardiovasc Electrophysiol 2008; 19:259-65. [DOI: 10.1111/j.1540-8167.2007.01057.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|