Effects of hypotonic shock on intracellular pH in bovine articular chondrocytes

Sánchez, Julio César; Wilkins, Robert J.

doi:10.1016/s1095-6433(03)00138-7

Cited by 21 publications

(24 citation statements)

References 40 publications

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“…7 It has been reported in previous studies that the anti-proliferative effect of hyperosmotic stress on chondrocytes is mediated by changes of the intracellular pH, 23,24 since cytosolic acidification is linked with inhibition of proliferation, mainly due to cell cycle arrest at the G1 phase. 25,26 We have demonstrated that increased osmolality leads to p38 MAPK activation IVD, GROWTH FACTORS AND OSMOLALITY in disc cells, which participates in the manifestation of the G2 arrest.…”

Section: Discussionmentioning

confidence: 99%

Effect of varying osmotic conditions on the response of bovine nucleus pulposus cells to growth factors and the activation of the ERK and Akt pathways

Mavrogonatou

Kletsas

2010

Journal Orthopaedic Research

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Intervertebral disc and especially nucleus pulposus is characterized by low cellularity. Additionally, extreme variations in osmolality are observed in this tissue, as a result of its specific physicochemical environment, daily activities, or degeneration. In this study, we investigated the role of osmotic fluctuations in the proliferative response of nucleus pulposus cells to exogenous growth factors. In particular, we examined the effect of platelet-derived growth factor (PDGF) and insulin-like growth factor-I (IGF-I) on the proliferation of bovine nucleus pulposus cells and on the activation of the MEK/ERK and PI-3-K/Akt pathways under varying osmotic conditions, in an effort to understand the mechanisms regulating cell proliferation in the intact and the degenerated intervertebral disc. Exposure of cells to high osmolality restrained novel DNA synthesis induced by PDGF or IGF-I in a dose-dependent manner and reduced ERK and Akt activation stimulated by serum or isolated growth factors. Our findings indicate that hyperosmolality imposes a strict control in intervertebral disc cells' proliferation, while hypo-osmotic conditions prevailing in degenerated discs may offer a more permissive environment for cellular proliferation. Keywords: intervertebral disc; growth factor; osmolality; ERK; Akt Back pain represents a major health problem and, although its exact etiology is not yet fully elucidated, it is associated with intervertebral disc degeneration.

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Section: Discussionmentioning

confidence: 99%

Effect of varying osmotic conditions on the response of bovine nucleus pulposus cells to growth factors and the activation of the ERK and Akt pathways

Mavrogonatou

Kletsas

2010

Journal Orthopaedic Research

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“…Electrophysiological studies have revealed the presence of voltage-gated Na + channels [8]; Voltage-gated K + channels [9][10][11][12]; Calcium-dependent K + channels [13]; stretch activated K + channels [14,15], and voltage-gated Cl -channels [8,16]. Pharmacological studies suggest the presence of a wider diversity that includes, besides the aforementioned, voltage-gated calcium channels [17][18][19]; TRPV channels [18] and aquaporins [20]. A few immunocytochemical studies have been made on chondrocytes, showing the expression of epithelial Na + channels [21] and Kv1.4, a shaker-related voltagedependent K + channel [12].…”

Section: Introductionmentioning

confidence: 99%

“…The current knowledge of chondrocyte ion channel diversity has been obtained from a variety of animal species, including chicken [9], cow [18], rabbit [16], dog [11], pig [10,15], horse, elephant [12] and human [22,23], but so far, no similar analysis has been carried out in rat, despite the value of this small mammal as a biological model. Therefore, the aim of this job was to study the presence of voltage-dependent potassium channels in rat articular chondrocytes by electrophysiological procedures, such as membrane potential measurements and whole cell patch clamp and compare the results with findings in other species.…”

Section: Introductionmentioning

confidence: 99%

Expression of Voltage Dependent Potassium Currents in Freshly Dissociated Rat Articular Chondrocytes

Ponce

2006

Cell Physiol Biochem

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The electrophysiological properties of voltage dependent potassium channels from freshly dissociated rat articular chondrocytes were studied. The resting membrane potential (-42.7±2.0 mV) was significantly depolarized by increasing concentrations of external potassium. No change was observed when external chloride concentration was varied. Addition of TEA, 4AP, α-Dendrotoxin and charybdotoxin depolarized resting membrane potential. Whole cell patch clamp studies revealed the presence of outwardly rectifying currents whose kinetic and pharmacological properties suggest the expression of voltage dependent potassium channels. Two kinds of currents were observed under the same experimental conditions. The first one, most frequently observed (80%), starts activating near -50 mV, with V_1/2=-18 mV, G_max=0.30 pS/pF. The second kind was observed in only 10% of cases; It activates near -40 mV, with_1/2=+28.35 mV, G_max=0.28 pS/pF pA/pF and does not inactivates. Inactivating currents were significantly inhibited by TEA (IC₅₀=1.45 mM), 4AP (IC₅₀=0.64 mM), CTX (IC₅₀≈10 nM), α-Dendrotoxin (IC₅₀ < 100 nM) and Margatoxin (IC₅₀=28.5 nM). These results show that rat chondrocytes express voltage dependent potassium currents and suggest a role of voltage-dependent potassium channels in regulating membrane potential of rat chondrocytes.

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“…Static hypotonic loading has been shown to change chondrocyte volume and intracellular pH, activate ion channels, and modulate cytoskeleton organization and aggrecan gene expression (13,21,27,50,51,62). These studies have adopted manual solution changes or employed specialized chambers to achieve osmotic loading (24,64).…”

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confidence: 99%

Chondrocyte intracellular calcium, cytoskeletal organization, and gene expression responses to dynamic osmotic loading

Chao¹,

West²,

Hung³

2006

American Journal of Physiology-Cell Physiology

107

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Effects of hypotonic shock on intracellular pH in bovine articular chondrocytes

Cited by 21 publications

References 40 publications

Effect of varying osmotic conditions on the response of bovine nucleus pulposus cells to growth factors and the activation of the ERK and Akt pathways

Effect of varying osmotic conditions on the response of bovine nucleus pulposus cells to growth factors and the activation of the ERK and Akt pathways

Expression of Voltage Dependent Potassium Currents in Freshly Dissociated Rat Articular Chondrocytes

Chondrocyte intracellular calcium, cytoskeletal organization, and gene expression responses to dynamic osmotic loading

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