Niflumic acid-induced increase in potassium currents in frog motor nerve terminals: effects on transmitter release

Miralles, Francisco Felip; Marsal, Jordi; Peres, Jaume; Solsona, Carles

doi:10.1016/0006-8993(95)01542-6

Cited by 6 publications

(4 citation statements)

References 39 publications

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“…This is presumably due to higher spontaneous activity at a higher temperature (35-37°C) used for tension recordings and/or due to the low permeability (efficacy) of niflumic acid in tissue level experiments. Also, it has been reported that niflumic acid activates K ϩ currents (25). This effect might be involved in the inhibitory action of niflumic acid on the ET-1-induced contraction.…”

Section: Discussionmentioning

confidence: 91%

Inward current oscillation underlying tonic contraction caused via ET_A receptors in pig detrusor smooth muscle

Kajioka¹,

Nakayama²,

McCoy³

et al. 2004

American Journal of Physiology-Renal Physiology

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Endothelin-1 (ET-1) is a powerful vasoconstricting peptide. Recent studies showed synthesis of ET-1 and the presence of ET receptors in urinary bladder smooth muscle cells. In the present study, we investigated the possible role of ET-1 in detrusor contraction and its underlying mechanisms in terms of electrical activity. ET-1 caused dose-dependent tonic contraction of bladder smooth muscle strips. Whole cell patch-clamp experiments revealed that ET-1 induced a single transient inward current in the majority of detrusor cells and that additional inward current oscillations were induced in one-third of the cells. The inward current oscillation and tonic contraction shared several characteristic features: 1) both activities lasted for a considerable time after ET-1 washout and 2) only prior application of ETA receptor antagonists, not ETB receptor antagonists, significantly suppressed ET-1-induced contractions and the oscillating inward currents. It was concluded that the inward current oscillation underlies ET-1-induced tonic contraction. Experiments with ion substitution and channel blockers suggested that periodic activation of Ca2+-activated Cl- channels caused the oscillating inward currents.

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Section: Discussionmentioning

confidence: 91%

Inward current oscillation underlying tonic contraction caused via ET_A receptors in pig detrusor smooth muscle

Kajioka¹,

Nakayama²,

McCoy³

et al. 2004

American Journal of Physiology-Renal Physiology

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“…Several lines of evidence indicate that Cl − channel blockers have profound influences on a variety of K + currents. For example, NFA is found to enhance the presynaptic voltage‐activated K + current (Miralles et al 1996), Ca 2+ ‐activated K + current (Miralles et al 1996), human ERG (ether‐a‐go‐go related gene) current (Malykhina et al 2002) and lipid‐sensitive mechano‐gated 2P domain K + current (Takahira et al 2005). In the present study, we found that the monocarboxylic acid‐derived Cl − channel blockers NPPB and NFA activated a macroscopic outward current at 0 mV in rat ventricular myocytes.…”

Section: Discussionmentioning

confidence: 99%

Effects of monocarboxylic acid‐derived Cl⁻ channel blockers on depolarization‐activated potassium currents in rat ventricular myocytes

Zhou

Zhang

Sun

et al. 2007

Experimental Physiology

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The effects of monocarboxylic acid-derived Cl(-) channel blockers on cardiac depolarization-activated K(+) currents were investigated. Membrane currents in rat ventricular myocytes were recorded using the whole-cell configuration of the patch-clamp technique. 5-Nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB) and niflumic acid (NFA) induced an outward current at 0 mV. Both NPPB and NFA failed to induce any current when used intracellularly or after K(+) in the bath and pipette solutions was replaced by equimolar Cs(+). Voltage pulse protocols revealed that NPPB and NFA enhanced the steady-state K(+) current but inhibited the transient outward K(+) current. Genistein, a tyrosine kinase (PTK) inhibitor, inhibited NPPB- and NFA-induced outward current. Another PTK inhibitor, lavendustin A, produced a comparable effect. In contrast, the inactive analogue of genistein, daidzein, was ineffective. Orthovanadate, a tyrosine phosphatase inhibitor, markedly slowed the deactivation of the outward current induced by NPPB and NFA. The protein kinase A (PKA) inhibitor H-89 inhibited NPPB-induced outward current at 0 mV. In contrast, the protein kinase C (PKC) inhibitor H-7 was without significant effect on the action of NPPB. Pretreatment of the myocytes with genistein or H-89 prevented the enhancing effect of NPPB. Increasing intracellular Cl(-) from 22 to 132 mm slightly reduced NPPB-induced outward current at 0 mV. These results demonstrate that the monocarboxylic acid-derived Cl(-) channel blockers NPPB and NFA enhance cardiac steady-state K(+) current, and suggest that the enhancing effect of the Cl(-) channel blockers is mediated by stimulation of PKA and PTK signalling pathways.

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“…In support of this, Reinsprecht et al (27) found La 3ϩ as effective as NA at inhibiting secretion from mast cells. Potentiation of potassium channels by NA, in particular the large-conductance, calciumactivated potassium channel, has also been noted (13,22,24). This effect occurs at NA Ͼ 50 M, whereas blockade of CaCC occurs below 50 M.…”

mentioning

confidence: 87%

Niflumic acid inhibits ATP-stimulated exocytosis in a mucin-secreting epithelial cell line

Bertrand¹,

Danahay²,

Poll³

et al. 2004

American Journal of Physiology-Cell Physiology

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Niflumic acid-induced increase in potassium currents in frog motor nerve terminals: effects on transmitter release

Cited by 6 publications

References 39 publications

Inward current oscillation underlying tonic contraction caused via ET_A receptors in pig detrusor smooth muscle

Inward current oscillation underlying tonic contraction caused via ET_A receptors in pig detrusor smooth muscle

Effects of monocarboxylic acid‐derived Cl⁻ channel blockers on depolarization‐activated potassium currents in rat ventricular myocytes

Niflumic acid inhibits ATP-stimulated exocytosis in a mucin-secreting epithelial cell line

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Niflumic acid-induced increase in potassium currents in frog motor nerve terminals: effects on transmitter release

Cited by 6 publications

References 39 publications

Inward current oscillation underlying tonic contraction caused via ETA receptors in pig detrusor smooth muscle

Inward current oscillation underlying tonic contraction caused via ETA receptors in pig detrusor smooth muscle

Effects of monocarboxylic acid‐derived Cl− channel blockers on depolarization‐activated potassium currents in rat ventricular myocytes

Niflumic acid inhibits ATP-stimulated exocytosis in a mucin-secreting epithelial cell line

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Inward current oscillation underlying tonic contraction caused via ET_A receptors in pig detrusor smooth muscle

Inward current oscillation underlying tonic contraction caused via ET_A receptors in pig detrusor smooth muscle

Effects of monocarboxylic acid‐derived Cl⁻ channel blockers on depolarization‐activated potassium currents in rat ventricular myocytes