Ionic currents in rat pulmonary and mesenteric arterial myocytes in primary culture and subculture

Yuan, Xiao-Jian; Goldman, W. F.; Tod, M.; Rubin, Lewis J.; Blaustein, Mordecai P.

doi:10.1152/ajplung.1993.264.2.l107

Cited by 56 publications

(47 citation statements)

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“…The explanation for this finding is not known. However, we speculate ␣ENaC expression in cultured VSMCs may represent an artifact of culturing, since expression of other ion channels and smooth musclespecific proteins required for contraction are also altered after culture (43,48). Alternatively, it is possible that the expression of ␣ENaC in freshly dispersed mrVSMC is suppressed below our detectable range.…”

Section: Discussionmentioning

confidence: 93%

Vascular ENaC proteins are required for renal myogenic constriction

Jernigan

Drummond

2005

American Journal of Physiology-Renal Physiology

130

164

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(VSMCs) to contract in response to increases in intraluminal pressure. Although mechanosensitive ion channels are thought to initiate VSMC stretch-induced contraction, their molecular identity is unknown. Recent reports suggest degenerin/epithelial Na ϩ channels (DEG/ENaC) may form mechanotransducers in sensory neurons and VSMCs; however, the role of DEG/ENaC proteins in myogenic constriction of mouse renal arteries has not been established. To test the hypothesis that DEG/ ENaC proteins are required for myogenic constriction in renal vessels, we first determined expression of ENaC transcripts and proteins in mouse renal VSMCs. Then, we determined pressure-and agonistinduced constriction and changes in vascular smooth muscle cytosolic Ca 2ϩ and Na ϩ in isolated mouse renal interlobar arteries following DEG/ENaC inhibition with amiloride and benzamil. We detect ␣-, ␤-, and ␥ENaC transcript and protein expression in cultured mouse renal VSMC. In contrast, we detect only ␤-and ␥-but not ␣ENaC protein in freshly dispersed mrVMSC. Selective DEG/ENaC inhibition, with low doses of amiloride and benzamil, abolishes pressure-induced constriction and increases in cytosolic Ca 2ϩ and Na ϩ without diminishing agonist-induced responses in isolated mouse interlobar arteries. Our findings indicate that DEG/ENaC proteins are required for myogenic constriction in mouse interlobar arteries and are consistent with our hypothesis that DEG/ENaC proteins may be components of mechanosensitive ion channel complexes required for myogenic vasoconstriction. mechanotransduction; renal blood flow autoregulation; amiloride; benzamil; isolated renal vessel; stretch-activated cation channel; calcium; sodium MYOGENIC VASOCONSTRICTION is an intrinsic property of most resistance vessels characterized by a decrease in luminal diameter in response to an increase in intraluminal pressure. The response is important in establishing basal vascular tone and maintaining blood flow autoregulation. It is well established that vascular smooth muscle (VSM) membrane depolarization and subsequent Ca 2ϩ influx via voltage-gated Ca 2ϩ channels mediate myogenic constriction (23,32,36). However, the mechanism that transduces mechanical stimuli (pressure-induced stretch) into a cellular event (depolarization) is less understood. Although mechanosensitive nonselective cation channels are thought to initiate pressure-induced depolarization (9,29,38,46), the molecule(s) involved has not been identified.Members of the degenerin/epithelial Na ϩ channel (DEG/ ENaC) family have recently been identified as mechanosensors in a variety of species and cell types (2,17,20,28,33). In mammals, DEG/ENaC proteins are found at several important sites of mechanotransduction, including dorsal root ganglion, arterial baroreflex sensory neurons, osteoblasts, keratinocytes, and vascular smooth muscle cells (VSMCs) (5, 12-14, 18, 30, 34). Two subfamilies of proteins are expressed in mammals: ENaC and acid-sensing ion channel. Acid-sensing ion channel proteins are activated by protons ...

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Section: Discussionmentioning

confidence: 93%

Vascular ENaC proteins are required for renal myogenic constriction

Jernigan

Drummond

2005

American Journal of Physiology-Renal Physiology

130

164

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“…PASMC from pulmonary arteries were prepared from male Sprague-Dawley rats (125-250 g) (72,73). The isolated pulmonary arterial branches (3rd-4th division) were incubated in Hanks' balanced salt solution (Biofluids) containing collagenase (1.5 mg/ml; Worthington) for 20 min.…”

Section: Methodsmentioning

confidence: 99%

PDGF stimulates pulmonary vascular smooth muscle cell proliferation by upregulating TRPC6 expression

Sweeney

Zhang

et al. 2003

American Journal of Physiology-Cell Physiology

320

316

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. PDGF stimulates pulmonary vascular smooth muscle cell proliferation by upregulating TRPC6 expression. Am J Physiol Cell Physiol 284: C316-C330, 2003; 10.1152/ajpcell.00125.2002 entry (CCE) through store-operated Ca 2ϩ (SOC) channels plays an important role in returning Ca 2ϩ to the sarcoplasmic reticulum (SR) and regulating cytosolic free Ca 2ϩ concentration ([Ca 2ϩ ]cyt). A rise in [Ca 2ϩ ]cyt and sufficient Ca 2ϩ in the SR are required for pulmonary artery smooth muscle cell (PASMC) proliferation. We tested the hypothesis that platelet-derived growth factor (PDGF)-mediated PASMC growth involves upregulation of c-Jun and TRPC6, a transient receptor potential cation channel. In rat PASMC, PDGF (10 ng/ml for 0.5-48 h) phosphorylated signal transducer and activator of transcription (STAT3), increased mRNA and protein levels of c-Jun, and stimulated cell proliferation. PDGF treatment also upregulated TRPC6 expression and augmented CCE, elicited by passive depletion of Ca 2ϩ from the SR using cyclopiazonic acid. Furthermore, overexpression of c-Jun stimulated TRPC6 expression and CCE amplitude in PASMC. Downregulation of TRPC6 using an antisense oligonucleotide specifically for human TRPC6 decreased CCE and inhibited PDGF-mediated PASMC proliferation. These results suggest that PDGF-mediated PASMC proliferation is associated with c-Jun/STAT3-induced upregulation of TRPC6 expression. The resultant increase in CCE raises [Ca 2ϩ ]cyt, facilitates return of Ca 2ϩ to the SR, and enhances PASMC growth. store-operated cation channels; pulmonary hypertension; vascular remodeling; platelet-derived growth factor PLATELET-DERIVED GROWTH FACTOR (PDGF) is an important autocrine and paracrine mitogen for vascular smooth muscle cells, mediating hyperplasia, hypertrophy, endoreduplication, and migration, and for pulmonary vascular remodeling (3,4,58,60,71). As a tyrosine kinase-coupled receptor agonist, PDGF is not only itself sufficient to initiate DNA synthesis and mitosis, but it is also a stimulus for its own expression (56) and synthesis of other mitogens such as endothelin-1 (ET-1) and heparin-binding epidermal growth factor in vascular smooth muscle cells (4). High levels of PDGF have been implicated in the blood and lung tissues of patients with primary and secondary pulmonary hypertension, suggesting a critical role of PDGF in the elevated pulmonary vascular resistance and pulmonary arterial pressure in these patients. Indeed, the mitogenic effect of PDGF on pulmonary artery smooth muscle cells (PASMC) has been demonstrated to contribute to the progression of pulmonary vascular wall remodeling in patients with pulmonary hypertension (3,26,58,60,64).Ionized Ca 2ϩ in the cytoplasm, intracellular organelles, and nucleus is a critical signal transduction element in many cell types (5,57,61,62). An increase in cytoplasmic free Ca 2ϩ concentration ([Ca 2ϩ ] cyt ) is a major trigger for smooth muscle contraction (57, 62) and an important stimulus for smooth muscle cell growth (6-8, 43). Removal (or chelation) of ext...

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“…Rat brain and pulmonary artery tissues were used in some experiments. Left and right branches of the main pulmonary artery along with intrapulmonary arterial branches were isolated from male Sprague-Dawley rats (125-250 g) (62). Brain tissues were usually removed from the same rats from which lungs were removed to prepare isolated extra-and intrapulmonary arteries.…”

Section: Methodsmentioning

confidence: 99%

Role of Na⁺/Ca²⁺ exchange in regulating cytosolic Ca²⁺ in cultured human pulmonary artery smooth muscle cells

Zhang

Yuan

Barrett

et al. 2005

American Journal of Physiology-Cell Physiology

119

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A rise in cytosolic Ca2+ concentration ([Ca2+]cyt) in pulmonary artery smooth muscle cells (PASMC) is an important stimulus for cell contraction, migration, and proliferation. Depletion of intracellular Ca2+ stores opens store-operated Ca2+ channels (SOC) and causes Ca2+ entry. Transient receptor potential (TRP) cation channels that are permeable to Na+ and Ca2+ are believed to form functional SOC. Because sarcolemmal Na+/Ca2+ exchanger has also been implicated in regulating [Ca2+]cyt, this study was designed to test the hypothesis that the Na+/Ca2+ exchanger (NCX) in cultured human PASMC is functionally involved in regulating [Ca2+]cyt by contributing to store depletion-mediated Ca2+ entry. RT-PCR and Western blot analyses revealed mRNA and protein expression for NCX1 and NCKX3 in cultured human PASMC. Removal of extracellular Na+, which switches the Na+/Ca2+ exchanger from the forward (Ca2+ exit) to reverse (Ca2+ entry) mode, significantly increased [Ca2+]cyt, whereas inhibition of the Na+/Ca2+ exchanger with KB-R7943 (10 μM) markedly attenuated the increase in [Ca2+]cyt via the reverse mode of Na+/Ca2+ exchange. Store depletion also induced a rise in [Ca2+]cyt via the reverse mode of Na+/Ca2+ exchange. Removal of extracellular Na+ or inhibition of the Na+/Ca2+ exchanger with KB-R7943 attenuated the store depletion-mediated Ca2+ entry. Furthermore, treatment of human PASMC with KB-R7943 also inhibited cell proliferation in the presence of serum and growth factors. These results suggest that NCX is functionally expressed in cultured human PASMC, that Ca2+ entry via the reverse mode of Na+/Ca2+ exchange contributes to store depletion-mediated increase in [Ca2+]cyt, and that blockade of the Na+/Ca2+ exchanger in its reverse mode may serve as a potential therapeutic approach for treatment of pulmonary hypertension.

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Ionic currents in rat pulmonary and mesenteric arterial myocytes in primary culture and subculture

Cited by 56 publications

References 0 publications

Vascular ENaC proteins are required for renal myogenic constriction

Vascular ENaC proteins are required for renal myogenic constriction

PDGF stimulates pulmonary vascular smooth muscle cell proliferation by upregulating TRPC6 expression

Role of Na⁺/Ca²⁺ exchange in regulating cytosolic Ca²⁺ in cultured human pulmonary artery smooth muscle cells

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Ionic currents in rat pulmonary and mesenteric arterial myocytes in primary culture and subculture

Cited by 56 publications

References 0 publications

Vascular ENaC proteins are required for renal myogenic constriction

Vascular ENaC proteins are required for renal myogenic constriction

PDGF stimulates pulmonary vascular smooth muscle cell proliferation by upregulating TRPC6 expression

Role of Na+/Ca2+ exchange in regulating cytosolic Ca2+ in cultured human pulmonary artery smooth muscle cells

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Role of Na⁺/Ca²⁺ exchange in regulating cytosolic Ca²⁺ in cultured human pulmonary artery smooth muscle cells