Environmentally persistent free radicals (EPFRs) in combustiongenerated particulate matter (PM) are capable of inducing pulmonary pathologies and contributing to the development of environmental asthma. In vivo exposure of infant rats to EPFRs demonstrates their ability to induce airway hyperresponsiveness to methacholine, a hallmark of asthma. However, the mechanisms by which combustionderived EPFRs elicit in vivo responses remain elusive. In this study, we used a chemically defined EPFR consisting of approximately 0.2 mm amorphrous silica containing 3% cupric oxide with the organic pollutant 1,2-dichlorobenzene (DCB-230). DCB-230 possesses similar radical content to urban-collected EPFRs but offers several advantages, including lack of contaminants and chemical uniformity. DCB-230 was readily taken up by BEAS-2B and at high doses (200 mg/cm 2 ) caused substantial necrosis. At low doses (20 mg/cm 2 ), DCB-230 particles caused lysosomal membrane permeabilization, oxidative stress, and lipid peroxidation within 24 hours of exposure. During this period, BEAS-2B underwent epithelial-to-mesenchymal transition (EMT), including loss of epithelial cell morphology, decreased E-cadherin expression, and increased a-smooth muscle actin (a-SMA) and collagen I production. Similar results were observed in neonatal air-liquid interface culture (i.e., disruption of epithelial integrity and EMT). Acute exposure of infant mice to DCB-230 resulted in EMT, as confirmed by lineage tracing studies and evidenced by coexpression of epithelial E-cadherin and mesenchymal a-SMA proteins in airway cells and increased SNAI1 expression in the lungs. EMT in neonatal mouse lungs after EPFR exposure may provide an explanation for epidemiological evidence supporting PM exposure and increased risk of asthma.Keywords: particulate matter; epithelial-mesenchymal transition; environmental asthma; pediatric Combustion-generated particulate matter (PM) from industrial processes and burning of biomass and fossil fuels has been linked with adverse pulmonary health effects (1). Environmental PM, both fine and ultrafine, is capable of airway deposition, alveolar penetration, respiratory distress, and exacerbation of preexisting pulmonary conditions. Previous studies highlight the potential roles of PM exposure in predisposing to asthma and pulmonary fibrosis (2-4). Additionally, PM has adjuvant effects when combined with innocuous antigen (5-7) and induces cellular damage, stimulating fibrotic remodeling in adult rodent exposure models (2). The developing pulmonary and immune systems are particularly vulnerable (8). We have developed a model for studying particulate exposures in neonatal rodents (, 7 d of age) (9), which we apply here to understand the effects of combustiongenerated environmentally persistent free radicals (EPFRs) on pulmonary airway remodeling.Delineation of the influences of particulate burden from the reactive chemical species complexed with the particulate has proven difficult. The nature of the chemical species drastically influences ...

Exposure to airborne particles is associated with increased cardiovascular morbidity and mortality. During the combustion of chlorine-containing hazardous materials and fuels, chlorinated hydrocarbons chemisorb to the surface of transition metal-oxide-containing particles, reduce the metal, and form an organic free radical. These radical-particle systems can survive in the environment for days and are called environmentally persistent free radicals (EPFRs). This study determined whether EPFRs could decrease left ventricular function before and after ischemia and reperfusion (I/R) in vivo. Male Brown Norway rats were dosed (8 mg/kg, i.t.) 24 hr prior to testing with particles containing the EPFR of 1, 2-dichlorobenzene (DCB230). DCB230 treatment decreased systolic and diastolic function. DCB230 also produced pulmonary and cardiac inflammation. After ischemia, systolic, but not diastolic function was significantly decreased in DCB230-treated rats. Ventricular function was not affected by I/R in control rats. There was greater oxidative stress in the heart and increased 8-isoprostane (biomarker of oxidative stress) in the plasma of treated vs control rats after I/R. These data demonstrate for the first time that DCB230 can produce inflammation and significantly decrease cardiac function at baseline and after I/R in vivo. Furthermore, these data suggest that EPFRs may be a risk factor for cardiac toxicity in healthy individuals and individuals with ischemic heart disease. Potential mechanisms involving cytokines/chemokines and/or oxidative stress are discussed.

Rationale Exceedingly little experimental research exists on the popular recreational drug mephedrone (4-methylmethcathinone) despite clinical reports concerning its behavioral and cardiovascular toxicity. Objective To characterize mephedrone preclinically by examining its capacity to: 1) serve as a discriminative stimulus, 2) disrupt the acquisition of response sequences, and 3) disrupt mean arterial pressure (MAP) and heart rate (HR). Methods and Results In one group of subjects that reliably discriminated 3.2 mg/kg of mephedrone from saline (n=9), substitution tests indicated that stimulants (cocaine, MDMA and methamphetamine) more closely approximated the mephedrone discriminative stimulus than non-stimulants (fenfluramine, morphine, and phencyclidine), although none fully substituted. In a second group (n=6), mephedrone (0.56–10 mg/kg, i.p.) dose-dependently decreased response rate and increased errors in both components of a procedure in which subjects either acquired a new response sequence each session (repeated acquisition) or completed the same response sequence each session (performance). Finally, in a third group (n=12), radio telemetry probes were used to measure the changes in MAP and HR elicited by mephedrone and then compared them to a known stimulant, methamphetamine. In these studies, mephedrone (0.01–9 mg/kg, i.v.) elicited increases in MAP and HR that were very similar to those elicited by methamphetamine (0.01–9 mg/kg, i.v.). The tachycardia and pressor responses to mephedrone (3 mg/kg) were blocked by the β-blocker atenolol (1 mg/kg, i.v.) and the α1, α2-blocker phentolamine (3 mg/kg, i.v.), respectively. Conclusions Mephedrone produces behavioral and cardiovascular responses that are similar to other stimulants; however, differences from the classical stimulants were also apparent.

Epidemiological studies have consistently linked inhalation of particulate matter (PM) to increased cardiac morbidity and mortality, especially in at risk populations. However, few studies have examined the effect of PM on baseline cardiac function in otherwise healthy individuals. In addition, airborne PM contain environmentally persistent free radicals (EPFR) capable of redox cycling in biological systems. The purpose of this study was to determine whether nose-only inhalation of EPFRs (20 min/day for 7 days) could decrease baseline left ventricular function in healthy male Sprague-Dawley rats. The model EPFR tested was 1,2-dichlorobenzene chemisorbed to 0.2-μm-diameter silica/CuO particles at 230°C (DCB230). Inhalation of vehicle or silica particles served as controls. Twenty-four hours after the last exposure, rats were anesthetized (isoflurane) and ventilated (3 l/min), and left ventricular function was assessed using pressure-volume catheters. Compared with controls, inhalation of DCB230 significantly decreased baseline stroke volume, cardiac output, and stroke work. End-diastolic volume and end-diastolic pressure were also significantly reduced; however, ventricular contractility and relaxation were not changed. DCB230 also significantly increased pulmonary arterial pressure and produced hyperplasia in small pulmonary arteries. Plasma levels of C-reactive protein were significantly increased by exposure to DCB230, as were levels of heme oxygenase-1 and SOD2 in the left ventricle. Together, these data show that inhalation of EPFRs, but not silica particles, decreases baseline cardiac function in healthy rats by decreasing cardiac filling, secondary to increased pulmonary resistance. These EPFRs also produced systemic inflammation and increased oxidative stress markers in the left ventricle.

We have previously reported that in salt-resistant rat phenotypes brain, Gαi 2 (guanine nucleotide–binding protein alpha inhibiting activity polypeptide 2) proteins are required to maintain blood pressure and sodium balance. However, the impact of hypothalamic paraventricular nucleus (PVN) Gαi 2 proteins on the salt sensitivity of blood pressure is unknown. Here, by the bilateral PVN administration of a targeted Gαi 2 oligodeoxynucleotide, we show that PVN-specific Gαi 2 proteins are required to facilitate the full natriuretic response to an acute volume expansion (peak natriuresis [μeq/min] scrambled (SCR) oligodeoxynucleotide 41±3 versus Gαi 2 oligodeoxynucleotide 18±4; P <0.05) via a renal nerve-dependent mechanism. Furthermore, in response to chronically elevated dietary sodium intake, PVN-specific Gαi 2 proteins are essential to counter renal nerve-dependent salt-sensitive hypertension (mean arterial pressure [mm Hg] 8% NaCl; SCR oligodeoxynucleotide 128±2 versus Gαi 2 oligodeoxynucleotide 147±3; P <0.05). This protective pathway involves activation of PVN Gαi 2 signaling pathways, which mediate sympathoinhibition to the blood vessels and kidneys (renal norepinephrine [pg/mg] 8% NaCl; SCR oligodeoxynucleotide 375±39 versus Gαi 2 oligodeoxynucleotide 850±27; P <0.05) and suppression of the activity of the sodium chloride cotransporter assessed as peak natriuresis to hydrochlorothiazide. Additionally, central oligodeoxynucleotide-mediated Gαi 2 protein downregulation prevented PVN parvocellular neuron activation, assessed by FosB immunohistochemistry, in response to increased dietary salt intake. In our analysis of the UK BioBank data set, it was observed that 2 GNAI2 single nucleotide polymorphism (SNP) (rs2298952, P =0.041; rs4547694, P =0.017) significantly correlate with essential hypertension. Collectively, our data suggest that selective targeting and activation of PVN Gαi 2 proteins is a novel therapeutic approach for the treatment of salt-sensitive hypertension.