Chronic hypoxia induces polycythemia, pulmonary hypertension, right ventricular hypertrophy, and weight loss. Hypoxia-inducible factor 1 (HIF-1) activates transcription of genes encoding proteins that mediate adaptive responses to hypoxia, including erythropoietin, vascular endothelial growth factor, glycolytic enzymes. Expression the HIF-1α subunit increases exponentially as O2 concentration is decreased. Hif1a–/– mouse embryos with complete deficiency due homozygosity for a null allele at...

Chronic hypoxic pulmonary hypertension is associated with profound vascular remodeling and alterations in Ca 2+ homeostasis arterial smooth muscle cells (PASMCs). Recent studies show that transient receptor potential (TRPC) genes, which encode store-operated receptor-operated cation channels, play important roles regulation cell proliferation. However, the influence of chronic hypoxia on TRPC channels has not been determined. Here we compared expression, store- entries PASMCs normoxic rats....

Chronic exposure to low-O2 tension induces pulmonary arterial hypertension (PAH), which is characterized by vascular remodeling and enhanced vasoreactivity. Recent evidence suggests that reactive oxygen species (ROS) may be involved in both processes. In this study, we critically examine the role superoxide NADPH oxidase plays development of chronic hypoxic PAH. hypoxia (CH; 10% O2 for 3 wk) caused a significant increase production intrapulmonary arteries (IPA) wild-type (WT) mice as...

In cardiac muscle, release of activator calcium from the sarcoplasmic reticulum occurs by calcium- induced through ryanodine receptors (RyRs), which are clustered in a dense, regular, two-dimensional lattice array at diad junction. We simulated numerically stochastic dynamics RyRs and L-type sarcolemmal channels interacting via nano-domains junctional cleft. Four putative RyR gating schemes based on single-channel measurements lipid bilayers all failed to give stable excitation–contraction...

Transient receptor potential melastatin- (TRPM) and vanilloid-related (TRPV) channels are nonselective cation pertinent to diverse physiological functions. Multiple TRPM TRPV channel subtypes have been identified cloned in different tissues. However, their information vascular tissue is scant. In this study, we sought identify expressed rat deendothelialized intralobar pulmonary arteries (PAs) aorta. With RT-PCR, mRNA of TRPM2, TRPM3, TRPM4, TRPM7, TRPM8 family TRPV1, TRPV2, TRPV3, TRPV4...

In skeletal muscle, dihydropyridine receptors are functionally coupled to ryanodine of the sarcoplasmic reticulum in triadic or diadic junctional complexes. cardiac muscle direct physical functional couplings have not been demonstrated. We tested hypothesis coupling L-type Ca2+ channels and rat myocytes by comparing efficacies triggering release when ion enters cell via Na+/Ca2+ exchanger. transported through was 20-160 times more effective than influx exchanger gating from reticulum,...

Chronic hypoxia depolarizes and reduces K + current in pulmonary arterial smooth muscle cells (PASMCs). Our laboratory previously demonstrated that hypoxia-inducible factor-1 (HIF-1) contributed to the development of hypoxic hypertension. In this study, electrophysiological parameters were measured PASMCs isolated from intrapulmonary arteries mice with one null allele at Hif1a locus encoding HIF-1α [ Hif1a(+/−)] their wild-type Hif1a(+/+)] littermates after 3 wk air or 10% O 2 . Hematocrit...

Transient receptor potential vanilloid 4 (TRPV4) is a mechanosensitive channel in pulmonary arterial smooth muscle cells (PASMCs). Its upregulation by chronic hypoxia associated with enhanced myogenic tone, and genetic deletion of trpv4 suppresses the development hypoxic hypertension (CHPH). Here we further examine roles TRPV4 agonist-induced vasoconstriction vasoreactivity CHPH. Initial evaluation TRPV4-selective antagonists HC-067047 RN-1734 KCl-contracted arteries (PAs) trpv4(-/-) mice...

In heart, a robust regulatory mechanism is required to counteract the regenerative Ca 2+ -induced release from sarcoplasmic reticulum. Several mechanisms, including inactivation, adaptation, and stochastic closing of ryanodine receptors (RyRs) have been proposed, but no conclusive evidence has yet provided. We probed termination process by using technique imaging local release, or “Ca spikes”, at subcellular sites; we tracked kinetics triggered L-type channels. At 0 mV, occurred terminated...

Ca 2+ release flux across the sarcoplasmic reticulum (SR) during cardiac excitation‐contraction coupling was investigated using a novel fluorescence method. Under whole‐cell voltage‐clamp conditions, rat ventricular myocytes were dialysed with high concentration of EGTA (4.0 m , 150 n free ), to minimize residence time released in cytoplasm, and low‐affinity, fast indicator, Oregon Green 488 BAPTA‐5N (OG‐5N; 1.0 K d ≈ 31 μ optimize detection localized [Ca ] site microdomains. Confocal...

In cardiac myocytes, calcium influx through the channel is primary pathway for triggering release. Recently it has been suggested that calcium-induced release mechanism can also be activated indirectly by sodium current, which elevates concentration under cell membrane, thereby favoring entry of "trigger" via sodium-calcium exchanger. To test this hypothesis, current was suppressed reducing external or applying tetrodotoxin. At potentials positive to -30 millivolts, unaffected. A small at...

Neuropilin-1 (Npn-1) is a cell surface receptor that binds vascular endothelial growth factor (VEGF), potent mediator of permeability, chemotaxis, and proliferation. In vitro, Npn-1 can complex with VEGF receptor-2 (VEGFR2) to enhance VEGFR2-mediated chemotaxis To determine the role Npn-1/VEGFR2 complexes in VEGF-induced barrier dysfunction, cells were stably transfected Npn1 or VEGFR2 alone (PAE/Npn PAE/KDR, respectively), (PAE/KDR/Npn-1). Permeability, estimated by measurement...

In the lung, chronic hypoxia (CH) causes pulmonary arterial smooth muscle cell (PASMC) depolarization, elevated endothelin-1 (ET-1), and vasoconstriction. We determined whether, during CH, depolarization-driven activation of L-type Ca 2+ channels contributes to 1) maintenance resting intracellular concentration ([Ca ] i ), 2) increased [Ca in response ET-1 (10 −8 M), 3) ET-1-induced contraction. Using indo 1 microfluorescence, we that PASMCs from intrapulmonary arteries rats exposed 10% O 2...

Chronic hypoxia causes pulmonary hypertension with vascular remodeling, increase in tone, and altered reactivity to agonists. These changes involve alterations multiple Ca 2+ pathways arterial smooth muscle cells (PASMCs). We have previously shown that vanilloid (TRPV)- melastatin-related transient receptor potential (TRPM) channels are expressed arteries (PAs). Here we found TRPV4 was the only member of TRPV TRPM subfamilies upregulated PAs chronic hypoxic rats. The expression occurred...

Key points A prolonged reduced oxygen level in the lungs, as occurs patients of many chronic lung diseases and residents living at high altitude, causes pulmonary hypertension characterized by profound structural functional changes vasculature. Many these are ascribed to alterations Ca 2+ homeostasis related cation channels arterial smooth muscle cells. Here we report increase an anion conductance called calcium‐activated chloride channel expression gene TMEM16A cells isolated from rats...

Hypoxic pulmonary hypertension is characterized by increased vascular tone, altered vasoreactivity, and remodeling, which are associated with alterations in Ca 2+ homeostasis arterial smooth muscle cells. We have previously shown that classical transient receptor potential 1 6 (TRPC1 TRPC6) upregulated arteries (PAs) of chronic hypoxic rats, but it unclear whether these channels essential for the development hypertension. Here we found was suppressed TRPC1 TRPC6 knockout ( Trpc1 −/− Trpc6 )...

Obesity leads to resistant hypertension and mechanisms are poorly understood, but high plasma levels of leptin have been implicated. Leptin increases blood pressure acting both centrally in the dorsomedial hypothalamus peripherally. Sites peripheral hypertensive effect not identified. We previously reported that enhanced activity carotid sinus nerve, which transmits chemosensory input from bodies (CBs) medullary centers, this was abolished by nonselective blockers Trp (transient receptor...

Although endothelin (ET)-1 is an important regulator of pulmonary vascular tone, little known about the mechanisms by which ET-1 causes contraction in this tissue. Using whole cell patch-clamp technique rat intrapulmonary arterial smooth muscle cells, we found that and voltage-dependent K + (K V )-channel antagonist 4-aminopyridine, but not Ca 2+ -activated -channel charybdotoxin (ChTX), caused membrane depolarization. In presence 100 nM ChTX, (10 −10 to 10 −7 M) a concentration-dependent...

1. Species differences in the activity of exchanger were evaluated isolated myocytes from rat, guinea‐pig, hamster ventricles and human atria. Fluorescence measurements using fura‐2 carried out conjunction with whole‐cell patch‐clamp technique for simultaneous recording membrane currents intracellular Ca2+ concentration. 2. release sarcoplasmic reticulum (SR) induced either by rapid application caffeine or current elicited inward Na(+)‐Ca2+ exchange (INa‐Ca). The magnitude INa‐Ca was largest...

To determine whether reactive oxygen species (ROS) play an essential role in hypoxic pulmonary vasoconstriction (HPV) and the cellular locus of ROS production action during HPV, we measured internal diameter (ID) at constant transmural pressure, lucigenin-derived chemiluminescence (LDCL), electron paramagnetic resonance (EPR) spin adduct spectra small distal porcine arteries, dichlorofluorescein (DCF) fluorescence myocytes isolated from these arteries. Hypoxia (4% O 2 ) decreased ID,...

The signaling of contraction by Ca2+ in the Syrian hamster (BIO 14.6) heart late stage cardiomyopathy (220 to 300 days old) was compared with that age-matched healthy hearts. Membrane current and cell shortening or intracellular transients were measured simultaneously isolated whole-cell-clamped myocytes. density L-type smaller myopathic than normal myocytes (2.13 +/- 0.3 versus 3.21 0.4 pA/pF at 0 mV, P < .05). In both control myocytes, gated release activation contraction. also...

To probe the molecular mechanism responsible for relaxant effect of catecholamines in heart muscle, we studied a monoclonal antibody (2D12) against phospholamban intact whole cell clamped guinea pig ventricular myocytes, which intracellular Ca2+ transient and current were simultaneously measured. The stimulated uptake sarcoplasmic reticular vesicles, shifting apparent dissociation constant activation by from 200 to 60 nM. stimulatory could be mimicked catalytic subunit adenosine 3',5'-cyclic...

Reactive oxygen species (ROS) generated from NADPH oxidases and mitochondria have been implicated as key messengers for pulmonary vasoconstriction vascular remodeling induced by agonists hypoxia. Since Ca(2+) mobilization is essential cell proliferation, we sought to characterize the response delineate pathways activated hydrogen peroxide (H(2)O(2)) in rat intralobar arterial smooth muscle cells (PASMCs). Exogenous application of 10 microM 1 mM H(2)O(2) elicited concentration-dependent...

Pulmonary hypertension (PH) is associated with profound vascular remodeling and alterations in Ca 2+ homeostasis pulmonary arterial smooth muscle cells (PASMCs). Previous studies show that canonical transient receptor potential (TRPC) genes are upregulated store-operated entry (SOCE) augmented PASMCs of chronic hypoxic rats patients (PAH). Here we further examine the involvement TRPC SOCE PH a widely used rat model monocrotaline (MCT)-induced PAH. Rats developed severe PAH, right ventricular...