Cigarette smoking is the single most important risk factor for the development of cardiovascular and pulmonary diseases (CVPD). Although cigarette smoking has been in constant decline since the 1950's, the introduction of e-cigarettes or electronic nicotine delivery systems 10 years ago has attracted former smokers as well as a new generation of consumers. Nicotine is a highly addictive substance, and it is currently unclear whether e-cigarettes are "safer" than regular cigarettes or whether they have the potential to reverse the health benefits, notably on the cardiopulmonary system, acquired with the decline of tobacco smoking. Of great concern, nicotine inhalation devices are becoming popular among young adults and youths, emphasizing the need for awareness and further study of the potential cardiopulmonary risks of nicotine and associated products. This review focuses on the interaction between nicotine and the renin-angiotensin system (RAS), one of the most important regulatory systems on autonomic, cardiovascular and pulmonary functions in both health and disease. The literature presented in this review strongly suggests that nicotine alters the homeostasis of the RAS by up-regulating the detrimental angiotensin converting enzyme (ACE)/Angiotensin (Ang)-II/Ang-II type 1 receptor (ATR) axis and down-regulating the compensatory ACE2/Ang-(1-7)/Mas receptor axis, contributing to the development of CVPD.
Mice with a knock-in mutation (Y524S) in the type I ryanodine receptor (RyR1) die when exposed to short periods of temperature elevation (≥ 37 °C). We demonstrate that treatment with 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) prevents heat-induced sudden death in Y524S mice. The AICAR protection is independent of AMPK activation and results from a newly identified action on the mutant RyR1 to reduce Ca2+ leak, preventing Ca2+ dependent increases in both reactive oxygen and reactive nitrogen species that act to further increase resting Ca2+ concentrations. If unchecked, the temperature driven increases in resting Ca2+ and ROS/RNS create an amplifying cycle that ultimately triggers sustained muscle contractions, rhabdomyolysis and death. Although antioxidants are effective in reducing this cycle in vitro, only AICAR prevents the heat induced death in vivo. Our findings suggest that AICAR is likely to be effective in prophylactic treatment of humans with enhanced susceptibility to exercise/heat-induced sudden death associated with RyR1 mutations.
Cigarette smoking is the single most important risk factor for the development of cardiovascular and pulmonary diseases; however, the role of nicotine in the pathogenesis of these diseases is incompletely understood. The purpose of this study was to examine the effects of chronic nicotine inhalation on the development of cardiovascular and pulmonary disease with a focus on blood pressure and cardiac remodeling. Male C57BL6/J mice were exposed to air (control) or nicotine vapor (daily, 12 hour on/12 hour off) for 8 weeks. Systemic blood pressure was recorded weekly by radio-telemetry, and cardiac remodeling was monitored by echocardiography. At the end of the 8 weeks, mice were subjected to right heart catheterization to measure right ventricular systolic pressure. Nicotine-exposed mice exhibited elevated systemic blood pressure from weeks 1 to 3, which then returned to baseline from weeks 4 to 8, indicating development of tolerance to nicotine. At 8 weeks, significantly increased right ventricular systolic pressure was detected in nicotine-exposed mice compared with the air controls. Echocardiography showed that 8-week nicotine inhalation resulted in right ventricular (RV) hypertrophy with increased RV free wall thickness and a trend of increase in RV internal diameter. In contrast, there were no significant structural or functional changes in the left ventricle following nicotine exposure. Mechanistically, we observed increased expression of angiotensin-converting enzyme and enhanced activation of mitogen-activated protein kinase pathways in the RV but not in the left ventricle. We conclude that chronic nicotine inhalation alters both systemic and pulmonary blood pressure with the latter accompanied by RV remodeling, possibly leading to progressive and persistent pulmonary hypertension.
Background:Rapamycin is a known inhibitor of protein synthesis but also modulates the activity of RyR1. Results: FKBP12 deficiency and low doses of either rapamycin or SLF increase, rather than decrease, protein synthesis and improve muscle function. Conclusion: In skeletal muscle, FKBP12 regulates Ca 2ϩ influx, Ca 2ϩ store refilling, and protein synthesis. Significance: This study lays the groundwork for the development of interventions to slow muscle fatigue.
The global targeted disruption of the natriuretic peptide receptor-A (NPRA) gene (Npr1) in mice provokes hypertension and cardiovascular dysfunction. The objective of this study was to determine the mechanisms regulating the development of cardiac fibrosis and dysfunction in Npr1 mutant mice. Npr1 knockout (Npr1−/−, 0-copy), heterozygous (Npr1+/−, 1-copy), and wild-type (Npr1+/+, 2-copy) mice were treated with the transforming growth factor (TGF)-β1 receptor (TGF-β1R) antagonist GW788388 (2 µg/g body weight/day; ip) for 28 days. Hearts were isolated and used for real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR), Western blot, and immunohistochemical analyses. The Npr1−/− (0-copy) mice showed a 6-fold induction of cardiac fibrosis and dysfunction with markedly induced expressions of collagen-1α (3.8-fold), monocyte chemoattractant protein (3.7-fold), connective tissue growth factor (CTGF, 5.3-fold), α-smooth muscle actin (α-SMA, 6.1-fold), TGF-βRI (4.3-fold), TGF-βRII (4.7-fold), and phosphorylated small mothers against decapentaplegic (pSMAD) proteins, including pSMAD-2 (3.2-fold) and pSMAD-3 (3.7-fold), compared with wild-type mice. The expressions of phosphorylated extracellular-regulated kinase ERK1/2 (pERK1/2), matrix metalloproteinases-2, -9, (MMP-2, -9), and proliferating cell nuclear antigen (PCNA) were also significantly upregulated in Npr1 0-copy mice. The treatment of mutant mice with GW788388 significantly blocked the expression of fibrotic markers, SMAD proteins, MMPs, and PCNA compared with the vehicle-treated control mice. The treatment with GW788388 significantly prevented cardiac dysfunctions in a sex-dependent manner in Npr1 0-copy and 1-copy mutant mice. The results suggest that the development of cardiac fibrosis and dysfunction in mutant mice is predominantly regulated through the TGF-β1-mediated SMAD-dependent pathway.
Nicotine is the addictive chemical in tobacco‐related products, such as cigarettes, water pipes, e‐cigs, and chewing tobacco. While the effects of smoke from cigarettes and cigars are well known, the rise in popularity of smokeless electronic cigarettes (e‐cigs) brings new questions about the effects of nicotine itself on the development of cardiovascular disease. These “smoke‐less” products have grown in popularity due to reduced costs, increased social acceptance, and a belief that e‐cigs are a less dangerous alternative to smoking, but very little is known about the cardiac effects of chronically inhaled nicotine.Thus the goal of our study is to investigate the effects of chronic nicotine exposure on cardiac function.C57BL/6 female mice aged 20 weeks were used in this study. Mice were exposed to nicotine vapors using a nicotine exposure chamber, in which home cages are placed in sealed chamber that provide control of air flow, chronicity, and nicotine vapor dose. Mice are exposed for 12 hours/day corresponding with the dark cycle during which they are active. Female mice exposed to nicotine vapor for five weeks showed a significant increased mean arterial blood pressure from baseline, (94.3 ± 1.1 mm Hg at baseline vs. 102.4 ± .1.8 mm Hg at five weeks; p<0.001). In addition, after five weeks nicotine exposure females were found to have decreased cardiac output (18.41 ± 2.23 ml/min for air exposed mice vs. 16.17 ± 2.08 ml/min for nicotine exposed mice; p<0.05) as well as thinner posterior walls at diastole (0.71 ± 0.1 mm for air exposed mice vs. 0.64 ± 0.1 mm for nicotine exposed mice; p<0.05).These findings suggest that nicotine inhalation alters cardiovascular function, leading to increased mean arterial blood pressure, reduced cardiac output, and thinned cardiac walls. This data indicates that nicotine may play a role in cardiac functional and structural decline. Potential future directions include investigating modulators of blood pressure, such as the renin‐angiotensin system, and measuring expression levels of pathways known to adversely regulate cardiomyocyte size, such as Atrogin‐1 and MuRF‐1, following nicotine exposure.Support or Funding InformationNIH NHLBI R01 HL135635This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
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