bluuebunny/crossref_metadata_2025 huggingface dataset:
Calcium-dependent arrhythmias in transgenic mice with heart failure
Authors: London Barry , Baker Linda C. , Lee Joon S. , Shusterman Vladimir , Choi Bum-Rak , Kubota Toru , McTiernan Charles F. , Feldman Arthur M. , Salama Guy
Published: March 2015

Transgenic mice overexpressing the inflammatory cytokine tumor necrosis factor (TNF)-α (TNF-α mice) in the heart develop a progressive heart failure syndrome characterized by biventricular dilatation, decreased ejection fraction, atrial and ventricular arrhythmias on ambulatory telemetry monitoring, and decreased survival compared with nontransgenic littermates. Programmed stimulation in vitro with single extra beats elicits reentrant ventricular arrhythmias in TNF-α ( n = 12 of 13 hearts) but not in control hearts. We performed optical mapping of voltage and Ca2+ in isolated perfused ventricles of TNF-α mice to study the mechanisms that lead to the initiation and maintenance of the arrhythmias. When compared with controls, hearts from TNF-α mice have prolonged of action potential durations (action potential duration at 90% repolarization: 23 ± 2 ms, n = 7, vs. 18 ± 1 ms, n = 5; P < 0.05), no increased dispersion of refractoriness between apex and base, elevated diastolic and depressed systolic [Ca2+], and prolonged Ca2+ transients (72 ± 6 ms, n = 10, vs. 54 ± 5 ms, n = 8; P < 0.01). Premature beats have diminished action potential amplitudes and conduct in a slow, heterogeneous manner. Lowering extracellular [Ca2+] normalizes conduction and prevents inducible arrhythmias. Thus both action potential prolongation and abnormal Ca2+ handling may contribute to the initiation of reentrant arrhythmias in this heart failure model by mechanisms distinct from enhanced dispersion of refractoriness or triggered activity.
Forebrain-mediated adaptations to myocardial infarction in the rat
Authors: Francis Joseph , Wei Shun-Guang , Weiss Robert M. , Beltz Terry , Johnson Alan Kim , Felder Robert B.
Published: March 2015

Recent studies suggest that the forebrain contributes to the circulatory derangements leading to heart failure after myocardial injury. We tested that hypothesis by examining the effect of myocardial infarction (MI) or sham MI (MI-s) on neurohumoral regulation in rats with prior anteroventral (AV) third ventricle lesion (AV3V-x) or sham lesion (AV3V-s). AV3V-s/MI rats had higher sodium intake, lower urine volume, and lower urinary sodium excretion than AV3V-s/MI-s rats. AV3V-x/MI rats had lower sodium intake and higher urine volume than AV3V-s/MI or AV3V-s/MI-s rats and urinary sodium excretion comparable to AV3V-s/MI-s rats. AV3V-x had no effect on baseline plasma renin activity (PRA). One week after MI, PRA had increased in AV3V-s but decreased in AV3V-x rats. AV3V-x reduced renal sympathetic nerve activity in MI and MI-s rats. AV3V-x improved baroreflex function in MI rats but diminished it in MI-s rats. Survival beyond 2 wk was lower in the AV3V-x/MI rats than in all other groups. These results confirm a critical role for the forebrain in the neurohumoral adjustments to MI.
Anandamide-induced vasorelaxation in rabbit aortic rings has two components: G protein dependent and independent
Authors: Mukhopadhyay Somnath , Chapnick Barry M. , Howlett Allyn C.
Published: March 2015

The endogenous cannabinoid anandamide (arachidonylethanolamide) produces vasorelaxation in different vascular beds. In the present study, we found that anandamide and a metabolically stable analog, methanandamide, produced dose-dependent (10 nM–10 μM) vasorelaxation of ∼80% in a rabbit aortic ring preparation in an endothelium-dependent manner. Non-endothelium-dependent vasorelaxation was observed to be a maximum of 20–22% at >10 μM methanandamide. The efficacious CB1 receptor analogs desacetyllevonantradol (10 μM) and WIN55212-2 (10 μM) failed to produce vasorelaxation; however, the endothelium-dependent vasorelaxation evoked by methanandamide was partially (75%) blocked by the CB1 receptor antagonist SR141716A. The VR1vanilloid receptor antagonist capsazepine or the calcitonin gene-related peptide (CGRP) antagonist CGRP-(8–37) partially attenuated (25%) the vasorelaxation in endothelium-intact preparations and greatly reduced the response in endothelium-denuded preparations. Pretreatment of aortic rings with N G-nitro-l-arginine methyl ester completely blocked the methanandamide-, capsaicin-, and CGRP-induced vasorelaxation. Pretreatment of aortic rings with pertussis toxin attenuated the methanandamide-induced vasorelaxation in endothelium-intact aortic rings, indicating the involvement of Gi/o proteins in the vasorelaxation; however, pertussis toxin treatment failed to block the endothelium-independent response. Thus, in the rabbit aorta, methanandamide-induced vasorelaxation exhibits two components: 1) in endothelium-intact rings, an SR141716A-sensitive, non-CB1receptor component that requires pertussis toxin-sensitive G proteins and nitric oxide (NO) production; and 2) in endothelium-denuded rings, a component that is mediated by VR1 vanilloid receptors and possibly by the subsequent release of CGRP that requires NO production but is independent of pertussis toxin-sensitive G proteins.
Elevated Ca2+transients and increased myofibrillar power generation cause cardiac hypercontractility in a model of Noonan syndrome with multiple lentigines
Authors: Clay Sarah A. , Domeier Timothy L. , Hanft Laurin M. , McDonald Kerry S. , Krenz Maike
Published: February 2015

Noonan syndrome with multiple lentigines (NSML) is primarily caused by mutations in the nonreceptor protein tyrosine phosphatase SHP2 and associated with congenital heart disease in the form of pulmonary valve stenosis and hypertrophic cardiomyopathy (HCM). Our goal was to elucidate the cellular mechanisms underlying the development of HCM caused by the Q510E mutation in SHP2. NSML patients carrying this mutation suffer from a particularly severe form of HCM. Drawing parallels to other, more common forms of HCM, we hypothesized that altered Ca2+homeostasis and/or sarcomeric mechanical properties play key roles in the pathomechanism. We used transgenic mice with cardiomyocyte-specific expression of Q510E-SHP2 starting before birth. Mice develop neonatal onset HCM with increased ejection fraction and fractional shortening at 4–6 wk of age. To assess Ca2+handling, isolated cardiomyocytes were loaded with fluo-4. Q510E-SHP2 expression increased Ca2+transient amplitudes during excitation-contraction coupling and increased sarcoplasmic reticulum Ca2+content concurrent with increased expression of sarco(endo)plasmic reticulum Ca2+-ATPase. In skinned cardiomyocyte preparations from Q510E-SHP2 mice, force-velocity relationships and power-load curves were shifted upward. The peak power-generating capacity was increased approximately twofold. Transmission electron microscopy revealed that the relative intracellular area occupied by sarcomeres was increased in Q510E-SHP2 cardiomyocytes. Triton X-100-based myofiber purification showed that Q510E-SHP2 increased the amount of sarcomeric proteins assembled into myofibers. In summary, Q510E-SHP2 expression leads to enhanced contractile performance early in disease progression by augmenting intracellular Ca2+cycling and increasing the number of power-generating sarcomeres. This gives important new insights into the cellular pathomechanisms of Q510E-SHP2-associated HCM.
Influence of estrogen on aortic stiffness and endothelial function in female rats
Authors: Tatchum-Talom Rabelais , Martel Céline , Marette André
Published: March 2015

Mechanisms underlying cardioprotective properties of estrogens are not fully understood. We evaluated effects of ovariectomy and estrogen replacement on arterial distensibility and endothelial function in rats. Sprague-Dawley rats were sham operated (Sham) or ovariectomized and treated with 17β-estradiol (OVX-E2) or vehicle (OVX) for 3 wk. Anesthetized rats were instrumented for measurement of central and peripheral arterial blood pressures and carotid and hindquarters blood flows. Arterial distensibility was evaluated in anesthetized rats on the basis of changes in thoracoabdominal pressure pulse wave velocity (PWV). PWV was calculated as the distance between the two central and peripheral cannula tips divided by transit time. Ovariectomy significantly reduced PWV (390 ± 19 and 472 ± 42 cm/s in OVX and Sham, respectively). Estrogen treatment completely normalized PWV (490 ± 37 cm/s). Estrogen-treated rats were associated with left ventricular hypertrophy and increased pulse pressure. Resting hemodynamic parameters were similar in all groups. Estrogen replacement significantly potentiated bradykinin vasodilatory responses in the hindlimb, but not in the carotid vascular bed. Hemodynamic responses to sodium nitroprusside and ANG II were similar in all groups. In conclusion, our results demonstrate for the first time that aortic stiffness determined by PWV is decreased in estrogen-deficient rats. Estrogen treatment increases aortic stiffness and potentiates endothelial vasodilator function in the hindquarters, but not in the carotid vascular bed, suggesting a regional heterogeneity in the modulatory influence of estrogen on vasomotor function.
Thromboxane A2 mimetic evokes a bradycardia mediated by stimulation of cardiac vagal afferent nerves
Authors: Wacker Michael J. , Tehrani Roya N. , Smoot Rory L. , Orr James A.
Published: March 2015

Injections of the thromboxane A2 mimetic U-46619 (10 and 20 μg) into the left atrium of anesthetized rabbits evoked decreases in heart rate (HR) and arterial blood pressure (ABP) followed by an increase in ABP. Bilateral, cervical vagotomy abolished the U-46619-induced bradycardia and attenuated the hypotension. Injections of U-46619 into the ascending aorta did not evoke the bradycardia and hypotension but did cause arterial hypertension. To further define the origin of the vagal reflex, recordings of nerve impulses were made from 11 chemosensitive cardiac vagal afferent nerves. Impulse frequency increased in all 11 fibers in response to left atrial injections of phenylbiguanide (20–30 μg) and U-46619 (5–10 μg). Onset time of nerve activity induced by U-46619 correlated with the onset time of bradycardia. We conclude that U-46619 injections into the left heart elicit decreases in HR and ABP via a vagal reflex that originates from the heart similar to the coronary chemoreflex described for other agents.
Enhanced contribution of NO to exercise-induced coronary responses after α-adrenergic receptor blockade
Authors: Takamura Masayuki , Parent Robert , Lavallée Michel
Published: March 2015

We hypothesized that nitric oxide (NO), in addition to β-adrenergic effects, may contribute to exercise-induced coronary responses after α-adrenergic receptor blockade. Data were analyzed as relationships between coronary sinus (CS) O2saturation (CS O2sat) or coronary blood flow (CBF) and myocardial O2consumption (MV˙o2). As MV˙o2increased, CS O2sat fell more ( P < 0.05) after Nω-nitro-l-arginine methyl ester (l-NAME; slope = −2.9 ± 0.4 × 10−2%saturation · μl O2· min−1· g−1) than before (slope = −2.1 ± 0.3 × 10−2%saturation · μl O2· min−1· g−1). The slope of CBF versus MV˙o2was not altered. After blockade of α-adrenergic receptors alone (phentolamine), CS O2sat failed to decrease as MV˙o2increased (slope = −0.1 ± 0.5 × 10−2%saturation · μl O2· min−1· g−1).l-NAME given after phentolamine led to substantial decreases in CS O2sat ( P < 0.01) as MV˙o2increased (slope = −2.1 ± 0.4 × 10−2percent saturation · μl O2−1· min−1· g−1). CBF responses to exercise were smaller ( P < 0.01) after phentolamine + l-NAME (slope = 6.1 ± 0.1 × 10−3ml/μl O2) than after phentolamine alone (slope = 6.9 ± 0.2 × 10−3ml/μl O2). Thus a significant portion of exercise-induced coronary responses after α-adrenergic receptor blockade involves NO formation.
Wine polyphenols improve cardiovascular remodeling and vascular function in NO-deficient hypertension
Authors: Bernátová Iveta , Pechánová Olga , Babál Pavel , Kyselá Sona , Stvrtina Svetoslav , Andriantsitohaina Ramaroson
Published: March 2015

The effects of the red wine polyphenolic compounds (Provinol) on hypertension, left ventricular hypertrophy, myocardial fibrosis, and vascular remodeling were investigated after chronic inhibition of nitric oxide (NO) synthase by administration of N G-nitro-l-arginine methyl ester (l-NAME) to rats. Rats were divided into four groups: a control group, a group treated for 4 wk with l-NAME (40 mg · kg−1 · day−1), and two groups treated with l-NAME followed by 3 wk of either spontaneous recovery or recovery with Provinol treatment (40 mg · kg−1 · day−1). Administration of Provinol produced a greater readiness of the decrease in blood pressure than that in the spontaneous recovery group. Provinol significantly depressed myocardial fibrosis and expedited the decrease in aortic cross-sectional area, the increase in endothelium-dependent relaxation, and the decrease in contraction of the aorta. These effects of Provinol were associated with a greater increase of NO synthase activity in the left ventricle and the aorta. The present study provides evidence that Provinol accelerates the regression of blood pressure and improves structural and functional cardiovascular changes produced by chronic inhibition of NO synthesis.
Exercise excess pressure and exercise-induced albuminuria in patients with type 2 diabetes mellitus
Authors: Climie Rachel E. D. , Srikanth Velandai , Keith Laura J. , Davies Justin E. , Sharman James E.
Published: February 2015

Exercise-induced albuminuria is common in patients with type 2 diabetes mellitus (T2DM) in response to maximal exercise, but the response to light-moderate exercise is unclear. Patients with T2DM have abnormal central hemodynamics and greater propensity for exercise hypertension. This study sought to determine the relationship between light-moderate exercise central hemodynamics (including aortic reservoir and excess pressure) and exercise-induced albuminuria. Thirty-nine T2DM (62 ± 9 yr; 49% male) and 39 nondiabetic controls (53 ± 9 yr; 51% male) were examined at rest and during 20 min of light-moderate cycle exercise (30 W; 50 revolutions/min). Albuminuria was assessed by the albumin-creatinine ratio (ACR) at rest and 30 min postexercise. Hemodynamics recorded included brachial and central blood pressure (BP), aortic stiffness, augmented pressure (AP), aortic reservoir pressure, and excess pressure integral (Pexcess). There was no difference in ACR between groups before exercise ( P > 0.05). Exercise induced a significant rise in ACR in T2DM but not controls (1.73 ± 1.43 vs. 0.53 ± 1.0 mg/mol, P = 0.002). All central hemodynamic variables were significantly higher during exercise in T2DM (i.e., Pexcess, systolic BP and AP; P < 0.01 all). In T2DM (but not controls), exercise Pexcesswas associated with postexercise ACR ( r = 0.51, P = 0.002), and this relationship was independent of age, sex, body mass index, heart rate, aortic stiffness, antihypertensive medication, and ambulatory daytime systolic BP (β = 0.003, P = 0.003). Light-moderate exercise induced a significant rise in ACR in T2DM, and this was independently associated with Pexcess, a potential marker of vascular dysfunction. These novel findings suggest that Pexcesscould be important for appropriate renal function in T2DM.
Gene transfer of extracellular SOD to the penis reduces O 2 − · and improves erectile function in aged rats
Authors: Bivalacqua Trinity J. , Armstrong Jeffrey S. , Biggerstaff John , Abdel-Mageed Asim B. , Kadowitz Philip J. , Hellstrom Wayne J. G. , Champion Hunter C.
Published: March 2015

Increased superoxide anion (O[Formula: see text]·) may contribute to vascular dysfunction in aging. In aged cavernosal tissue, lucigenin-enhanced chemiluminescence demonstrated a threefold increase in superoxide formation, and the oxidative fluorescent probe hydroethidine indicated higher superoxide levels throughout the aged penis. This increase in superoxide was associated with impaired cavernosal nerve-mediated and agonist-induced erectile responses, increased nitrotyrosine staining, and lower cGMP levels, but no compensatory change in cavernosal extracellular (EC)-superoxide dismutase (EC-SOD) mRNA or protein. In vivo adenoviral (Ad) gene transfer of EC-SOD to the penis resulted in higher expression of EC-SOD mRNA, protein, SOD activity, cGMP levels, and lower nitrotyrosine staining. Transfection with AdCMVEC-SOD resulted in a significant increase in erectile response to cavernosal nerve stimulation, ACh, and zaprinast to a magnitude similar to young rats. These data provide evidence in support of the hypothesis that erectile dysfunction associated with aging is related in part to an increase in cavernosal O[Formula: see text]· formation. Gene-transfer of EC-SOD reduces superoxide formation and restores age-associated erectile function and may represent a novel therapeutic target for the treatment of erectile dysfunction.
Influence of peroxynitrite on energy metabolism and cardiac function in a rat ischemia-reperfusion model
Authors: Lee Warren H. , Gounarides John S. , Roos Eric S. , Wolin Michael S.
Published: March 2015

Ischemia-reperfusion generates peroxynitrite (ONOO–), which interacts with many of the systems altered by ischemia-reperfusion. This study examines the influence of endogenously produced ONOO– on cardiac metabolism and function. Nitro-l-arginine (an inhibitor of ONOO– biosynthesis) and urate (a scavenger of ONOO–) were utilized to investigate potential pathophysiological roles for ONOO– in a rat Langendorff heart model perfused with glucose-containing saline at constant pressure and exposed to 30 min of ischemia followed by 60 min of reperfusion. In this model, ischemia-reperfusion decreased contractile function (e.g., left ventricular developed pressure), cardiac work (rate-pressure product), efficiency of O2 utilization, membrane-bound creatine kinase activity, and NMR-detectable ATP and creatine phosphate without significantly altering the recovery of coronary flow, heart rate, lactate release, and muscle pH. Treatment with urate and nitro-l-arginine produced a substantial recovery of left ventricular developed pressure, rate-pressure product, efficiency of O2 utilization, creatine kinase activity, and NMR-detectable creatine phosphate and a partial recovery of ATP. The pattern of effects observed in this study and in previously published work with similar models suggests that ONOO– may alter key steps in the efficiency of mitochondrial high-energy phosphate generation.
Regional cerebral blood flow in cats with cross-linked hemoglobin transfusion during focal cerebral ischemia
Authors: Rebel Annette , Ulatowski John A. , Joung Karena , Bucci Enrico , Traystman Richard J. , Koehler Raymond C.
Published: March 2015

841, 2002. First published November 8, 2001; 10.1152/ajpheart. 00880.2001.—The beneficial effect of hemodilution on cerebral blood flow (CBF) during focal cerebral ischemia is mitigated by reduced arterial oxygen content (CaO2). In anesthetized cats subjected to permanent middle cerebral artery occlusion, the time course of regional CBF was evaluated after isovolemic exchange transfusion with either albumin or a tetrameric hemoglobin-based oxygen carrier. The transfusion started 30 min after arterial occlusion. We tested the hypothesis that bulk oxygen transport (CBF × CaO2) to ischemic tissue is increased by hemoglobin transfusion at a hematocrit of 18% compared with albumin-transfused cats at a hematocrit of 18% or control cats at a hematocrit of 30% and equivalent arterial pressure. In the nonischemic hemisphere, CBF increased selectively after albumin transfusion, and oxygen transport was similar among groups. In the ischemic cortex, albumin transfusion increased CBF, but oxygen transport was not increased above that of the control group. Hemoglobin transfusion increased both CBF and oxygen transport in the ischemic cortex above values in the control group, but the increase was delayed until 4 h of ischemia. Consequently, acute injury volume measured at 6 h of ischemia was not significantly attenuated. In contrast to the cortex, CBF in the ischemic caudate nucleus was not substantially increased by either albumin or hemoglobin transfusion. Therefore, in a large animal model of permanent focal ischemia in which transfusion starts 30 min after ischemia, tetrameric cross-linked hemoglobin transfusion can augment oxygen transport to the ischemic cortex, but the increase can be delayed and not necessarily provide protection. Moreover, an end-artery region such as the caudate nucleus is less likely to benefit from hemodilution.
Cyclical mechanical stretch-induced apoptosis in myocytes from young rats but necrosis in myocytes from old rats
Authors: Husse B. , Sopart A. , Isenberg G.
Published: March 2015

Mechanical load as stimulus for apoptosis and necrosis could be responsible for the loss of cardiomyocytes. Ventricular myocytes from young (3 mo) and old (14–24 mo) rats underwent cyclical mechanical stretch (CMS; 5% elongation, 1 Hz) for 24 h. Spontaneous apoptosis was in myocytes from young rats 0.33 ± 0.12% and from old rats 1.05 ± 0.35% [Tdt-mediated dUTP nick-end labeling (TUNEL) assay]; associated with a decrease of Bcl-2. CMS increased the apoptosis to 0.58 ± 0.18% in myocytes from young rats. Western blot analysis showed that CMS reduced Bcl-2 and increased p53 (young rats). Bax was not changed by CMS. These were confirmed by cytochrome c release (31 ± 13%) and by the enrichment of cytosolic nucleosomes (11 ± 8%). CMS did not influence the apoptosis in myocytes from old rats (TUNEL assay, Bcl-2, Bax, or p53). CMS did not cause necrosis in myocytes from young rats. CMS increased the number of necrotic cells by showing the cell membrane rupture in myocytes from old rats (50 ± 13% 5-hexadecanoylaminofluorescein-positive and 38 ± 6% propidium iodide-positive cells) as well as by measuring the lactate dehydrogenase release. The results suggest that CMS-induced apoptosis in myocytes of young rats but necrosis in myocytes from old rats, which could be attributed to more stress sensitivity of cells from old rats.
Adenosine receptors mediate glutamate-evoked arteriolar dilation in the rat cerebral cortex
Authors: Iliff Jeffrey J. , D'Ambrosio Raimondo , Ngai Al C. , Winn H. Richard
Published: March 2015

We tested the hypothesis that adenosine (Ado) mediates glutamate-induced vasodilation in the cerebral cortex by monitoring pial arteriole diameter in chloralose-anesthetized rats equipped with closed cranial windows. Topical application of 100 μM glutamate and 100 μM N-methyl-d-aspartate (NMDA) dilated pial arterioles (baseline diameter 25 ± 2 μm) by 17 ± 1% and 18 ± 4%, respectively. Coapplication of the nonselective Ado receptor antagonist theophylline (Theo; 10 μM) significantly reduced glutamate- and NMDA-induced vasodilation to 4 ± 2% ( P < 0.01) and 6 ± 2% ( P < 0.05), whereas the Ado A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (0.1 μM) had no effect. Moreover, application of the Ado A2A receptor-selective antagonist 4-{2-[7-amino-2-(2-furyl)(1,2,4)triazolo(2,3-a)(1,3,5)triazin-5-ylamino]ethyl}phenol (ZM-241385), either by superfusion (0.1 μM, 1 μM) or intravenously (1 mg/kg), significantly inhibited the pial arteriole dilation response to glutamate. Neither Theo nor ZM-241385 affected vascular reactivity to mild hypercapnia induced by 5% CO2 inhalation. These results suggest that Ado contributes to the dilation of rat cerebral arterioles induced by exogenous glutamate, and that the Ado A2A receptor subtype may be involved in this dilation response.
Association between coronary lesion severity and distal microvascular resistance in patients with coronary artery disease
Authors: Chamuleau Steven A. J. , Siebes Maria , Meuwissen Martijn , Koch Karel T. , Spaan Jos A. E. , Piek Jan J.
Published: March 2015

Homogeneity of microvascular resistance in different perfusion areas of the same heart is generally assumed. We investigated the effect of the severity of an epicardial stenosis on microvascular resistance in 27 patients with coronary artery disease and stable angina. All patients had an angiographically normal coronary artery, an artery with an intermediate lesion, and an artery with a severe lesion; the latter was treated with angioplasty. In each patient, distal blood flow velocity and pressure were measured during baseline and maximal hyperemia (induced by intracoronary adenosine) using a Doppler and pressure guide wire, respectively. The ratio of mean distal pressure to average peak blood flow velocity was used as an index for the microvascular resistance (MRv). Within patients, the hyperemic MRv was higher in arteries with more severe stenosis ( P = 0.021). After percutaneous transluminal coronary angioplasty (PTCA), the hyperemic MRv decreased (pre-PTCA, 2.6 vs. post-PTCA, 1.9 mmHg·cm–1s–1, P < 0.01) toward the value of the reference artery (1.7 mmHg·cm–1s–1; P = 0.67). We conclude that there is a positive association between coronary lesion severity and variability of distal microvascular resistance that normalizes after angioplasty. This study challenges the concept of uniform distribution of hyperemic MRv that is relevant for the interpretation of both noninvasive and invasive diagnostic tests.
Heme oxygenase activity in placenta: direct dependence on oxygen availability
Authors: Appleton Scott D. , Marks Gerald S. , Nakatsu Kanji , Brien James F. , Smith Graeme N. , Graham Charles H.
Published: March 2015

Carbon monoxide (CO), which is formed endogenously from heme catalyzed by heme oxygenase (HO), is proposed to play a role in vascular control. The mRNA and protein expression of the inducible isoform of HO (HO-1) increases in response to hypoxia, and it has been assumed that HO activity also increases. This assumption requires evaluation because the catalytic activity of HO requires three molecules of O2for each molecule of CO formed from heme, and HO activity may be limited by O2availability. To test the hypothesis that low physiological O2concentrations limit HO activity, heme-derived CO formation by microsomal fractions of homogenates of chorionic villi of human placentas was determined after exposure to 0, 1, 5, or 21% O2. Results revealed that HO activity was directly dependent on O2concentration. Thus, although hypoxia may increase HO protein and mRNA expression, there is a progressive decrease in HO activity with decreasing O2concentration and the dependence of HO activity on O2concentration is similar in chorionic villi from noninfarcted areas of preeclamptic and normotensive placenta.
PPAR-α effects on the heart and other vascular tissues
Authors: Francis Gordon A. , Annicotte Jean-Sébastien , Auwerx Johan
Published: March 2015

Peroxisome proliferator-activated receptor (PPAR)-α is a member of a large nuclear receptor superfamily whose main role is to activate genes involved in fatty acid oxidation in the liver, heart, kidney, and skeletal muscle. While currently used mainly as hypolipidemic agents, the cardiac effects and anti-inflammatory actions of PPAR-α agonists in arterial wall cells suggest other potential cardioprotective and antiatherosclerotic effects of these agents. This review summarizes current knowledge regarding the effects of PPAR-α agonists on lipid and lipoprotein metabolism, the heart, and the vessel wall and introduces some of the insights gained in these areas from studying PPAR-α-deficient mice. The introduction of new and more potent PPAR-α agonists will provide important insights into the overall benefits of activating PPAR-α clinically for the treatment of dyslipidemia and prevention of vascular disease.
Fibrinolysis-inhibitory capacity of clot-embedded surfactant is enhanced by SP-B and SP-C
Authors: Markart Philipp , Ruppert Clemens , Grimminger Friedrich , Seeger Werner , Günther Andreas
Published: March 2015

Incorporation of pulmonary surfactant into fibrin inhibits its plasmic degradation. In the present study we investigated the influence of surfactant proteins (SP)-A, SP-B, and SP-C on the fibrinolysis-inhibitory capacity of surfactant phospholipids. Plasmin-induced fibrinolysis was quantified by means of a125I-fibrin plate assay, and surfactant incorporation into polymerizing fibrin was analyzed by measuring the incorporation of3H-labeled L-α-dipalmitoylphosphatidylcholine into the insoluble clot material. Incorporation of a calf lung surfactant extract (Alveofact) and an organic extract of natural rabbit large surfactant aggregates (LSA) into a fibrin clot revealed a stronger inhibitory effect on plasmic cleavage of this clot than a synthetic phospholipid mixture (PLX) and unprocessed LSA. Reconstitution of PLX with SP-B and SP-C increased, whereas reconstitution with SP-A decreased, the fibrinolysis-inhibitory capacity of the phospholipids. The SP-B effect was paralleled by an increased incorporation of phospholipids into fibrin. We conclude that the inhibitory effect of surfactant incorporation into polymerizing fibrin on its susceptibility to plasmic cleavage is enhanced by SP-B and SP-C but reduced by SP-A. In the case of SP-B, increased phospholipid incorporation may underlie this finding.
Iron increases expression of iron-export protein MTP1 in lung cells
Authors: Yang Funmei , Wang Xinchao , Haile David J. , Piantadosi Claude A. , Ghio Andrew J.
Published: March 2015

Accumulation of reactive iron in acute and chronic lung disease suggests that iron-driven free radical formation could contribute to tissue injury. Safe transport and sequestration of this metal is likely to be of importance in lung defense. We provide evidence for the expression and iron-induced upregulation of the metal transporter protein-1 (MTP1) genes in human and rodent lung cells at both the protein and mRNA levels. In human bronchial epithelial cells, a 3.8-fold increase in mRNA level and a 2.4-fold increase in protein level of MTP1 were observed after iron exposure. In freshly isolated human macrophages, as much as an 18-fold increase in the MTP1 protein level was detected after incubation with an iron compound. The elevation in expression of MTP1 gene was also demonstrated in iron-instilled rat lungs and in hypotransferrinemic mouse lungs. This is similar to our previous findings with divalent metal transporter-1 (DMT1), an iron transporter that is required for iron uptake and intracellular iron trafficking. These studies suggest the presence of iron mobilization and/or detoxification pathways in the lung that are crucial for iron homeostasis and lung defense.
Induction of endotoxin tolerance improves lung function after warm ischemia in dogs
Authors: Friedrich Ivar , Spillner Jan , Lu Er-Xiong , Barnscheidt Markus , Kuss Oliver , Sablotzki Armin , Schade F. Ulrich , Börgermann Jochen
Published: March 2015

In shock models, induction of endotoxin tolerance (ET) is known to have a protective effect. The present study was designed to explore if ET is effective in protecting lungs from reperfusion injury. Twelve foxhounds were used as experimental animals. After a left thoracotomy, the left hilum was clamped for 3 h, followed by 8 h of reperfusion. In the treatment group (ET, n = 6), dogs were pretreated with incremental daily endotoxin doses of up to 60 μg/kg on day 6. The ischemia and reperfusion experiment was carried out on day 9. Control group animals ( n = 6) were not subjected to endotoxin. After 8 h of observation, functional parameters of the reperfused lung of the ET and the control group were statistically different ( P < 0.05) with respect to Po2[ET vs. control: 172.7 ± 12.9 vs. 66.1 ± 7.2 (SE) mmHg], compliance (16.0 ± 1.2 vs. 8.3 ± 1.0 ml/0.1 kPa), and the wet-to-dry ratio (9.4 ± 0.8 vs. 16.7 ± 1.2). After 3 h of warm ischemia and 8 h of reperfusion, pulmonary function and lung water content improved in the endotoxin-tolerant group.
β-Adrenoceptor-mediated control of apical membrane conductive properties in fetal distal lung epithelia
Authors: Collett A. , Ramminger S. J. , Olver R. E. , Wilson S. M.
Published: March 2015

Distal lung epithelial cells isolated from fetal rats were cultured (48 h) on permeable supports so that transepithelial ion transport could be quantified electrometrically. Unstimulated cells generated a short-circuit current ( Isc) that was inhibited (∼80%) by apical amiloride. The current is thus due, predominantly, to the absorption of Na+from the apical solution. Isoprenaline increased the amiloride-sensitive Iscabout twofold. Experiments in which apical membrane Na+currents were monitored in basolaterally permeabilized cells showed that this was accompanied by a rise in apical Na+conductance ( GNa+). Isoprenaline also increased apical Cl−conductance ( GCl−) by activating an anion channel species sensitive to glibenclamide but unaffected by 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS). The isoprenaline-evoked changes in GNa+and GCl−could account for the changes in Iscobserved in intact cells. Glibenclamide had no effect upon the isoprenaline-evoked stimulation of Iscor GNa+demonstrating that the rise in GCl−is not essential to the stimulation of Na+transport.
Implications for matrix metalloproteinases as modulators of pediatric lung disease
Authors: Winkler Margaret K. , Foldes Jane K. , Bunn Robert C. , Fowlkes John L.
Published: March 2015

Matrix metalloproteinases (MMPs) are a large family (>20) of cation-dependent proteinases believed to be important modulators of normal human lung development and potentially harmful mediators of lung damage. Little is known about MMP production and secretion by the lung during childhood or how alterations in MMP levels may be involved in lung damage. We examined endotracheal aspirates from children (<19 years) without lung disease for the presence of MMP activity. Only gelatinase activity was detectable, and inhibitor profiles suggest they represented one or more MMPs. Comparison of gelatinase activity, MMP expression, and MMP activity in children without pulmonary disease with children who required mechanical ventilation for respiratory failure show: 1) gelatinase activity was approximately five- to sixfold higher in respiratory failure; 2) MMP-7, MMP-8, and MMP-9 concentrations and MMP-8 and MMP-9 activities were markedly elevated in respiratory failure; and 3) MMP-7, MMP-8, and MMP-9 levels were significantly correlated in children with lung disease. These studies provide compelling evidence that specific MMPs are present in the diseased lung and may participate in the pathogenesis of pediatric respiratory failure.
Temporal regulation of cytokine mRNA expression by tristetraprolin: dynamic control by p38 MAPK and MKP-1
Authors: Prabhala Pavan , Bunge Kristin , Rahman Md. Mostafizur , Ge Qi , Clark Andrew R. , Ammit Alaina J.
Published: February 2015

Cytokines drive many inflammatory diseases, including asthma. Understanding the molecular mechanisms responsible for cytokine secretion will allow us to develop novel strategies to repress inflammation in the future. Harnessing the power of endogenous anti-inflammatory proteins is one such strategy. In this study, we investigate the p38 MAPK-mediated regulatory interaction of two anti-inflammatory proteins, mitogen-activated protein kinase phosphatase 1 (MKP-1) and tristetraprolin (TTP), in the context of asthmatic inflammation. Using primary cultures of airway smooth muscle cells in vitro, we explored the temporal regulation of IL-6 cytokine mRNA expression upon stimulation with TNF-α. Intriguingly, the temporal profile of mRNA expression was biphasic. This was not due to COX-2-derived prostanoid upregulation, increased expression of NLRP3 inflammasome components, or upregulation of the cognate receptor for TNF-α-TNFR1. Rather, the biphasic nature of TNF-α-induced IL-6 mRNA expression was regulated temporally by the RNA-destabilizing molecule, TTP. Importantly, TTP function is controlled by p38 MAPK, and our study reveals that its expression in airway smooth muscle cells is p38 MAPK-dependent and its anti-inflammatory activity is also controlled by p38 MAPK-mediated phosphorylation. MKP-1 is a MAPK deactivator; thus, by controlling p38 MAPK phosphorylation status in a temporally distinct manner, MKP-1 ensures that TTP is expressed and made functional at precisely the correct time to repress cytokine expression. Together, p38 MAPK, MKP-1, and TTP may form a regulatory network that exerts significant control on cytokine secretion in proasthmatic inflammation through precise temporal signaling.
Human bronchial epithelial cells express PAR-2 with different sensitivity to thermolysin
Authors: Ubl Joachim J. , Grishina Zoryana V. , Sukhomlin Tatiana K. , Welte Tobias , Sedehizade Fariba , Reiser Georg
Published: March 2015

Protease-activated receptor-2 (PAR-2) plays a role in inflammatory reactions in airway physiology. Proteases cleaving the extracellular NH2 terminus of receptors activate or inactivate PAR, thus possessing a therapeutic potential. Using RT-PCR and immunocytochemistry, we show PAR-2 in human airway epithelial cell lines human bronchial epithelial (HBE) and A549. Functional expression of PAR-2 was confirmed by Ca2+imaging studies using the receptor agonist protease trypsin. The effect was abolished by soybean trypsin inhibitor and mimicked by the specific PAR-2 peptide agonist SLIGKV. Amplitude and duration of PAR-2-elicited Ca2+ response in HBE and A549 cells depend on concentration and time of agonist superfusion. The response is partially pertussis toxin (PTX) insensitive, abolished by the phospholipase C inhibitor U-73122, and diminished by the inositol 1,4,5-trisphosphate receptor antagonist 2-aminoethoxydiphenyl borate. Cathepsin G altered neither the resting Ca2+ level nor PAR-2-elicited Ca2+response. Thermolysin, a prototypic bacterial metalloprotease, induced a dose-dependent Ca2+ response in HBE, but not A549, cells. In both cell lines, thermolysin abolished the response to a subsequent trypsin challenge but not to SLIGKV. Thus different epithelial cell types express different PAR-2 with identical responses to physiological stimuli (trypsin, SLIGKV) but different sensitivity to modifying proteases, such as thermolysin.
IL-13-induced Clara cell secretory protein expression in airway epithelium: role of EGFR signaling pathway
Authors: Kim Suil , Shim Jae Jeong , Burgel Pierre-Regis , Ueki Iris F. , Dao-Pick Trang , Tam Dominic Cheng-Wei , Nadel Jay A.
Published: March 2015

Previous work showed that the Th2 cytokine interleukin (IL)-13 induces goblet cell metaplasia via an indirect mechanism involving the expression and subsequent activation of epidermal growth factor receptor (EGFR). Because Clara cell secretory protein (CCSP) expression has been reported in cells that express mucins, we examined the effect of IL-13 on CCSP gene and protein expression in pathogen-free rat airways and in pulmonary mucoepidermoid NCI-H292 cells. Intratracheal instillation of IL-13 induced CCSP mRNA in epithelial cells without cilia within 8–16 h, maximal between 24 and 48 h; CCSP immunostaining increased in a time-dependent fashion, maximal at 48 h. The CCSP immunostaining was localized in nongranulated secretory cells and goblet cells and in the lumen. Pretreatment with the selective EGFR tyrosine kinase inhibitor BIBX1522, cyclophosphamide (an inhibitor of bone marrow leukocyte mobilization), or a blocking antibody to IL-8 prevented CCSP staining. Treatment of NCI-H292 cells with the EGFR ligand transforming growth factor-α, but not with IL-13 alone, induced CCSP gene and protein expression. Selective EGFR tyrosine kinase inhibitors, BIBX1522 and AG1478, prevented CCSP expression in NCI-H292 cells, but the platelet-derived growth factor receptor tyrosine kinase inhibitor AG1295 had no effect. These findings indicate that IL-13 induces CCSP expression via an EGFR- and leukocyte-dependent pathway.
Dynamics of metalloproteinase-2 and -9, TGF-β, and uPA activities during normoxic vs. hyperoxic alveolarization
Authors: Buckley S. , Warburton D.
Published: March 2015

The final stage of lung development, alveolarization, continues after birth in humans and rodents. Clinical interventions, such as oxygen therapy, in the first week of life can adversely impact alveolar formation. We compared alveolarization in the rat neonate under normal vs. hyperoxic conditions, examining gelatinase, transforming growth factor (TGF)-β, and the protease urokinase-type plasminogen activator (uPA) activities in whole lung and cultured type II alveolar epithelial cells (AEC2). The dynamic induction of gelatinase, TGF-β, and uPA activities seen in neonatal lungs during the first days of life was significantly impacted by hyperoxia. In whole lung, gelatinase and TGF-β activities were increased, while uPA activity was decreased. At the level of the epithelium, AEC2 isolated from hyperoxic rat pups early in life secreted less active TGF-β, less active gelatinases, and less active uPA than control neonatal AEC2. AEC2 from hyperoxic pups also expressed increased levels of proliferating cell nuclear antigen early in life compared with control neonatal AEC2, suggesting that oxygen-induced proliferation and/or repair were occurring. The developmental profile of neonatal lung was perturbed within a day of initiating oxygen treatment, suggesting that putative palliative treatments should be coadministered with oxygen therapy.
Pulmonary vascular K+ channel expression and vasoreactivity in a model of congenital heart disease
Authors: Cornfield David N. , Resnik Ernesto R. , Herron Jean M. , Reinhartz Olaf , Fineman Jeffrey R.
Published: March 2015

K+channels play an important role in mediating pulmonary vasodilation caused by increased oxygen tension, nitric oxide, alkalosis, and shear stress. To test the hypothesis that lung K+ channel gene expression may be altered by chronic increases in pulmonary blood flow, we measured gene and protein expression of calcium-sensitive (KCa) and voltage-gated (Kv2.1) K+ channels, and a pH-sensitive K+channel (TASK), in distal lung from fetal lambs in which an aortopulmonary shunt was placed at 139 days gestation. Under baseline conditions, animals with an aortopulmonary shunt showed elevated pulmonary artery pressure and pulmonary blood flow compared with twin controls. Hypoxia caused a greater increase in pulmonary vascular tone in shunt animals compared with controls. Alkalosis caused pulmonary vasodilation in control but not shunt animals. To determine lung K+ channel mRNA levels, we performed quantitative RT-PCR. In comparison with control animals, lung KCa channel mRNA content was increased in shunt animals, whereas TASK mRNA levels were decreased. There was no difference in Kv2.1 mRNA levels. Channel protein expression was consistent with these findings. We conclude that, in the presence of elevated pulmonary blood flow, KCachannel expression is increased and TASK is decreased.
Inhibition of alveolarization and altered pulmonary mechanics in mice expressing GATA-6
Authors: Liu Cong , Ikegami Machiko , Stahlman Mildred T. , Dey Chitta R. , Whitsett Jeffrey A.
Published: March 2015

GATA-6, a member of a family of zinc finger transcription factors, is expressed in epithelial cells of the developing lung. To further assess the role of GATA-6 in lung morphogenesis, GATA-6 was expressed in respiratory epithelial cells of the developing mouse lung under control of the surfactant protein C promoter (hSP-CGATA-6 mice). Although GATA-6 did not alter lung morphology at embryonic day 18.5, defects in alveolar septation were observed early in the neonatal period, and air space enlargement persisted to adulthood. Airway resistance, airway elastance, tissue damping, and tissue elastance were significantly decreased, and lung volumes were significantly increased at 12 wk of age. Normal postnatal morphogenesis of the lung depends upon precise temporal-spatial regulation of GATA-6.
Altered fatty acid composition of lung surfactant phospholipids in interstitial lung disease
Authors: Schmidt R. , Meier U. , Markart P. , Grimminger F. , Velcovsky H. G. , Morr H. , Seeger W. , Günther A.
Published: March 2015

Deterioration of pulmonary surfactant function has been reported in interstitial lung disease; however, the molecular basis is presently unclear. We analyzed fatty acid (FA) profiles of several surfactant phospholipid classes isolated from large-surfactant aggregates of patients with idiopathic pulmonary fibrosis (IPF; n = 12), hypersensitivity pneumonitis ( n = 5), and sarcoidosis ( n = 12). Eight healthy individuals served as controls. The relative content of palmitic acid in phosphatidylcholine was significantly reduced in IPF (66.8 ± 2.5%; means ± SE; P < 0.01) but not in hypersensitivity pneumonitis (78.5 ± 1.8%) and sarcoidosis (78.2 ± 3.1%; control 80.1 ± 0.7%). In addition, the phosphatidylglycerol FA profile was significantly altered in the IPF patients, with a lower relative content of its major FA, oleic acid, at the expense of saturated FA. In the phosphatidylcholine class, a significant correlation between the impairment of biophysical surfactant function and decreased percentages of palmitic acid was noted. We conclude that significant alterations in the FA profile of pulmonary surfactant phospholipids occur predominantly in IPF and may contribute to the disturbances of alveolar surface activity in this disease.
Control of the development of the pulmonary surfactant system in the saltwater crocodile,Crocodylus porosus
Authors: Sullivan Lucy C. , Orgeig Sandra , Daniels Christopher B.
Published: March 2015

Pulmonary surfactant is a mixture of lipids and proteins that controls the surface tension of the fluid lining the inner lung. Its composition is conserved among the vertebrates. Here we hypothesize that the in ovo administration of glucocorticoids and thyroid hormones during late incubation will accelerate surfactant development in the saltwater crocodile, Crocodylus porosus. We also hypothesize that the increased maturation of the type II cells in response to hormone pretreatment will result in enhanced responsiveness of the cells to surfactant secretagogues. We sampled embryos at days 60, 68, and 75 of incubation and after hatching. We administered dexamethasone (Dex), 3,5,3′-triiodothyronine (T3), or a combination of both hormones (Dex + T3), 48 and 24 h before each prehatching time point. Lavage analysis indicated that the maturation of the phospholipids (PL) in the lungs of embryonic crocodiles occurs rapidly. Only T3and Dex + T3increased total PL in lavage at embryonic day 60, but Dex, T3, and Dex + T3increased PL at day 75. The saturation of the PLs was increased by T3and Dex + T3at day 68. Swimming exercise did not increase the amount or alter the saturation of the surfactant PLs. Pretreatment of embryos with Dex, T3, or Dex + T3changed the secretion profiles of the isolated type II cells. Dex + T3increased the response of the cells to agonists at days 60and 68. Therefore, glucocorticoids and thyroid hormones regulate surfactant maturation in the crocodile.