Decreased inward rectifier and voltage-gated K+ currents of the right septal coronary artery smooth muscle cells in pulmonary arterial hypertensive rats

Endothelin-1 (ET-1) increases intracellular Ca2+ concentration ([Ca2+]i) in pulmonary arterial smooth muscle cells (PASMCs); however, the mechanisms for Ca2+ mobilization are not clear. We determined the contributions of extracellular influx and intracellular release to the ET-1-induced Ca2+ response using Indo 1 fluorescence and electrophysiological techniques. Application of ET-1 (10−10 to 10−8 M) to transiently (24–48 h) cultured rat PASMCs caused concentration-dependent increases in [Ca2+]i. At 10−8 M, ET-1 caused a large, transient increase in [Ca2+]i (>1 μM) followed by a sustained elevation in [Ca2+]i(<200 nM). The ET-1-induced increase in [Ca2+]i was attenuated (<80%) by extracellular Ca2+ removal; by verapamil, a voltage-gated Ca2+-channel antagonist; and by ryanodine, an inhibitor of Ca2+ release from caffeine-sensitive stores. Depleting intracellular stores with thapsigargin abolished the peak in [Ca2+]i, but the sustained phase was unaffected. Simultaneously measuring membrane potential and [Ca2+]i indicated that depolarization preceded the rise in [Ca2+]i. These results suggest that ET-1 initiates depolarization in PASMCs, leading to Ca2+influx through voltage-gated Ca2+ channels and Ca2+ release from ryanodine- and inositol 1,4,5-trisphosphate-sensitive stores.

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Inward rectifier K+ currents in smooth muscle cells from rat coronary arteries: block by Mg2+, Ca2+, and Ba2+

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1996.271.2.h696 ◽

1996 ◽

Vol 271 (2) ◽

pp. H696-H705 ◽

Cited By ~ 24

Author(s):

B. E. Robertson ◽

A. D. Bonev ◽

M. T. Nelson

Keyword(s):

Smooth Muscle ◽

Membrane Potential ◽

Coronary Artery ◽

Smooth Muscle Cells ◽

Coronary Arteries ◽

Inward Rectifier ◽

Inward Rectification ◽

K Channels ◽

Inward Currents ◽

K Currents

Inward rectifier K+ channels have been implicated in the control of membrane potential and external K(+)-induced dilations of small coronary arteries. To identify and characterize inward rectifier K+ currents in coronary artery smooth muscle, whole cell K+ currents in smooth muscle cells enzymatically isolated from rat coronary (septal) arteries (diameters, 100-150 microns) were measured in the conventional and perforated configurations of the patch-clamp technique. Ba(2+)-sensitive, whole cell K+ current-voltage relationships exhibited inward rectification. Blockers of Ca(2+)-activated K+ channels (1 mM tetraethylammonium ion), ATP-sensitive K+ channels (10 microM glibenclamide), and voltage-dependent K+ channels (1 mM 4-aminopyridine) in smooth muscle did not affect inward rectifier K+ currents. The nonselective K+ channel inhibitor phencyclidine (100 microM) reduced inward rectifier K+ currents by approximately 50%. External Ba2+ reduced inward currents, with membrane potential hyperpolarization increasing inhibition. The half-inhibition constant for Ba2+ was 2.1 microM at -60 mV, decreasing e-fold for a 25-mV hyperpolarization. External Cs+ also blocked inward rectifier K+ currents, with the half-inhibition constant for Cs+ of 2.9 mM at -60 mV. External Ca2+ and Mg2+ reduced inward rectifier K+ currents. At -60 mV, Ca2+ and Mg2+ (1 mM) reduced inward currents by 33 and 21%, respectively. Inward rectification was not affected by dialysis of the cell's interior with a nominally Ca(2+)- and Mg(2+)-free solution. These findings indicate that inward rectifier K+ channels exist in coronary artery smooth muscle and that Ba2+ may be a useful probe for the functional role of inward rectifier K+ channels in coronary arteries.

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Ca(2+)-activated and voltage-gated K+ currents in smooth muscle cells isolated from human mesenteric arteries.

The Journal of Physiology ◽

10.1113/jphysiol.1992.sp019386 ◽

1992 ◽

Vol 457 (1) ◽

pp. 431-454 ◽

Cited By ~ 55

Author(s):

S V Smirnov ◽

P I Aaronson

Keyword(s):

Smooth Muscle ◽

Smooth Muscle Cells ◽

Muscle Cells ◽

Mesenteric Arteries ◽

Voltage Gated ◽

K Currents

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Voltage-Gated Potassium+ Channel Expression in Coronary Artery Smooth Muscle Cells of SHR and WKY

Cell Biochemistry and Biophysics ◽

10.1007/s12013-014-0120-4 ◽

2014 ◽

Vol 70 (3) ◽

pp. 1725-1731 ◽

Cited By ~ 1

Author(s):

Zhi Hu ◽

Aiqun Ma ◽

Yushun Zhang ◽

Yutao Xi ◽

Lihong Fan ◽

...

Keyword(s):

Smooth Muscle ◽

Coronary Artery ◽

Smooth Muscle Cells ◽

Potassium Channel ◽

Muscle Cells ◽

Voltage Gated ◽

Channel Expression

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Glucose-6-phosphate dehydrogenase plays a critical role in hypoxia-induced CD133+ progenitor cells self-renewal and stimulates their accumulation in the lungs of pulmonary hypertensive rats

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00303.2013 ◽

2014 ◽

Vol 307 (7) ◽

pp. L545-L556 ◽

Cited By ~ 16

Author(s):

Sukrutha Chettimada ◽

Sachindra Raj Joshi ◽

Abdallah Alzoubi ◽

Sarah A. Gebb ◽

Ivan F. McMurtry ◽

...

Keyword(s):

Pulmonary Hypertension ◽

Smooth Muscle ◽

Smooth Muscle Cells ◽

Progenitor Cells ◽

Muscle Cells ◽

G6pd Activity ◽

Hypertensive Rats ◽

Self Renewal ◽

Pulmonary Arterial ◽

Glucose 6 Phosphate Dehydrogenase

Although hypoxia is detrimental to most cell types, it aids survival of progenitor cells and is associated with diseases like cancer and pulmonary hypertension in humans. Therefore, understanding the underlying mechanisms that promote survival of progenitor cells in hypoxia and then developing novel therapies to stop their growth in hypoxia-associated human diseases is important. Here we demonstrate that the proliferation and growth of human CD133+ progenitor cells, which contribute to tumorigenesis and the development of pulmonary hypertension, are increased when cultured under hypoxic conditions. Furthermore, glucose-6-phosphate dehydrogenase (G6PD) activity was increased threefold in hypoxic CD133+ cells. The increased G6PD activity was required for CD133+ cell proliferation, and their growth was arrested by G6PD inhibition or knockdown. G6PD activity upregulated expression of HIF1α, cyclin A, and phospho-histone H3, thereby promoting CD133+ cell dedifferentiation and self-renewal and altering cell cycle regulation. When CD133+ cells were cocultured across a porous membrane from pulmonary artery smooth muscle cells (PASMCs), G6PD-dependent H2O2 production and release by PASMCs recruited CD133+ cells to the membrane, where they attached and expressed smooth muscle markers (α-actin and SM22α). Inhibition of G6PD reduced smooth muscle marker expression in CD133+ cells under normoxia but not hypoxia. In vivo, CD133+ cells colocalized with G6PD+ cells in the perivascular region of lungs from rats with hypoxia-induced pulmonary hypertension. Finally, inhibition of G6PD by dehydroepiandrosterone in pulmonary arterial hypertensive rats nearly abolished CD133+ cell accumulation around pulmonary arteries and the formation of occlusive lesions. These observations suggest G6PD plays a key role in increasing hypoxia-induced CD133+ cell survival in hypertensive lungs that differentiate to smooth muscle cells and contribute to pulmonary arterial remodeling during development of pulmonary hypertension.

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Subacute hypoxia suppresses Kv3.4 channel expression and whole-cell K+ currents through endogenous 15-hydroxyeicosatetraenoic acid in pulmonary arterial smooth muscle cells

European Journal of Pharmacology ◽

10.1016/j.ejphar.2008.02.031 ◽

2008 ◽

Vol 587 (1-3) ◽

pp. 187-195 ◽

Cited By ~ 39

Author(s):

Lei Guo ◽

Xiaobo Tang ◽

Hua Tian ◽

Ye Liu ◽

Zhigang Wang ◽

...

Keyword(s):

Smooth Muscle ◽

Smooth Muscle Cells ◽

Muscle Cells ◽

Hydroxyeicosatetraenoic Acid ◽

Whole Cell ◽

Channel Expression ◽

Pulmonary Arterial ◽

Arterial Smooth Muscle Cells ◽

Pulmonary Arterial Smooth Muscle ◽

K Currents

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Role of ET-1 receptor binding and [Ca2+]i in contraction of coronary arteries from DOCA-salt hypertensive rats

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00627.2001 ◽

2002 ◽

Vol 282 (5) ◽

pp. H1944-H1949 ◽

Cited By ~ 8

Author(s):

Ararat D. Giulumian ◽

Mariela M. Molero ◽

Vikram B. Reddy ◽

Jennifer S. Pollock ◽

David M. Pollock ◽

...

Keyword(s):

Smooth Muscle ◽

Coronary Artery ◽

Smooth Muscle Cells ◽

Receptor Binding ◽

Muscle Cells ◽

Intraluminal Pressure ◽

Endothelin Receptor ◽

Hypertensive Rats ◽

Small Arteries

Hypertension is associated with an increase in coronary artery disease, but little is known about the regulation of coronary vascular tone by endothelin-1 (ET-1) in hypertension. The present study evaluated the mechanisms mediating altered contraction to ET-1 in coronary small arteries from deoxycorticosterone acetate (DOCA)-salt hypertensive rats. DOCA-salt rats exhibited an increase in systolic blood pressure and plasma ET-1 levels compared with placebo rats. Contraction to ET-1 (1 × 10−11 to 3 × 10−8 M), measured in isolated coronary small arteries maintained at a constant intraluminal pressure of 40 mmHg, was largely reduced in vessels from DOCA-salt rats compared with placebo rats. To determine the role of endothelin receptor binding in the impaired contraction to ET-1,125I-labeled ET-1 receptor binding was measured in membranes isolated from coronary small arteries. Maximum binding (fmol/mg protein) and binding affinity were similar in coronary membranes from DOCA-salt rats compared with placebo rats. Changes in intracellular Ca2+ concentration ([Ca2+]i) were measured in freshly dissociated coronary small artery smooth muscle cells loaded with fura 2. ET-1 (10−9 M) produced a 30 ± 9% increase in [Ca2+]i in smooth muscle cells from placebo rats, but had no effect on cells from DOCA-salt rats (2 ± 2%). In summary, the ET-1-induced coronary artery contraction and increase in [Ca2+]i are impaired in DOCA-salt hypertensive rats, whereas endothelin receptor binding is not altered. These results suggest endothelin receptor uncoupling from signaling mechanisms and indicate that impaired [Ca2+]isignaling contributes to the decrease in ET-1-induced contraction of coronary small arteries in DOCA-salt hypertensive rats.

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