Effects of methylene blue and ascorbate on transmembrane potential in frog skeletal muscle

Nánási, Péter P.; Dely, M.

doi:10.1016/0306-3623(95)00007-n

Cited by 3 publications

(1 citation statement)

References 10 publications

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“…Based on our findings, we speculate that some of the cardiovascular effects of MB are mediated by inhibition of K ATP channels. In previous investigations, MB, in concentration ranges used in the present study, was reported to induce depolarizations in various cell types in a cGMP-independent manner [ 40 , 55 , 56 , 57 ]. Depolarization by suppression of K ATP channels has been demonstrated to cause activation of voltage-gated Ca 2+ channels and to increase intracellular Ca 2+ levels, and a subsequent vasoconstriction in vascular beds (for reviews, [ 17 , 22 ]).…”

Section: Discussionmentioning

confidence: 76%

Methylene Blue Inhibits Cromakalim-Activated K+ Currents in Follicle-Enclosed Oocytes

et al. 2023

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The effects of methylene blue (MB) on cromakalim-induced K+ currents were investigated in follicle-enclosed Xenopus oocytes. In concentrations ranging from 3–300 μM, MB inhibited K+ currents (IC50: 22.4 μM) activated by cromakalim, which activates KATP channels. MB inhibited cromakalim-activated K+ currents in a noncompetitive and voltage-independent manner. The respective EC50 and slope values for cromakalim-activation of K+ currents were 194 ± 21 µM and 0.91 for controls, and 206 ± 24 µM and 0.87 in the presence of 30 μM MB. The inhibition of cromakalim-induced K+ currents by MB was not altered by pretreatment with the Ca2+ chelator BAPTA, which suggests that MB does not influence Ca2+-activated second messenger pathways. K+ currents mediated through a C-terminally deleted form of Kir6.2 (KirΔC26), which does not contain the sulfonylurea receptor, were still inhibited by MB, indicating direct interaction of MB with the channel-forming Kir6.2 subunit. The binding characteristics of the KATP ligand [3H]glibenclamide are not altered by MB in a concentration range between 1 μM-1 mM, as suggested by radioligand binding assay. The presence of a membrane permeable cGMP analogue (8-Br-cGMP, 100 µM) and a guanylate cyclase activator (BAY 58-2667, 3 µM) did not affect the inhibitory effects of MB, suggesting that MB does not inhibit cromakalim-activated K+ currents through guanylate cyclase. Collectively, these results suggest that MB directly inhibits cromakalim-activated K+ currents in follicular cells of Xenopus oocytes.

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Section: Discussionmentioning

confidence: 76%

Methylene Blue Inhibits Cromakalim-Activated K+ Currents in Follicle-Enclosed Oocytes

et al. 2023

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Cellular and molecular actions of Methylene Blue in the nervous system

Öz

Lorke

Al‐Hasan

et al. 2010

Medicinal Research Reviews

349

249

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Methylene Blue (MB), following its introduction to biology in the 19 th century by Ehrlich, has found uses in various areas of medicine and biology. At present, MB is the first line of treatment in methemoglobinemias, is used frequently in the treatment of ifosfamide-induced encephalopathy, and is routinely employed as a diagnostic tool in surgical procedures. Furthermore, recent studies suggest that MB has beneficial effects in Alzheimer's disease and memory improvement. Although the modulation of the cGMP pathway is considered the most significant effect of MB, mediating its pharmacological actions, recent studies indicate that it has multiple cellular and molecular targets. In the majority of cases, biological effects and clinical applications of MB are dictated by its unique physicochemical properties including its planar structure, redox chemistry, ionic charges, and light spectrum characteristics. In this review article, these physicochemical features and the actions of MB on multiple cellular and molecular targets are discussed with regard to their relevance to the nervous system.

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Vitamins C and E Modulate Neuronal Potassium Currents

Alshuaib

Mathew

2006

J Membrane Biol

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We investigated the effects of vitamins C and E on the delayed-rectifier potassium current (IK(DR)), which is important in repolarizing the membrane potential, and on the transient A-type potassium current (IK(A)), which regulates neuronal firing frequency. The whole-cell patch-clamp technique was used to measure the currents from cultured Drosophila neurons derived from embryonic neuroblasts. The membrane potential was stepped to different voltages between -40 and +60 mV from a holding potential of -80 mV. IK(DR) and IK(A) measured in the vitamin C-containing solution (IK(DR) 305 +/- 16 pA, IK(A) 11 +/- 2 pA) were smaller than those measured in the control solution (488 +/- 21 pA, IK(A )28 +/- 3 pA). By contrast, IK(DR) and IK(A) measured in the vitamin E-containing solution (IK(DR) 561 +/- 21 pA, IK(A )31 +/- 3 pA) were greater than those measured in the control solution (422 +/- 15 pA, 17 +/- 2 pA). These results indicate that vitamins C and E can modulate potassium current amplitudes and possibly lead to altered neuronal excitability.

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Effects of methylene blue and ascorbate on transmembrane potential in frog skeletal muscle

Cited by 3 publications

References 10 publications

Methylene Blue Inhibits Cromakalim-Activated K+ Currents in Follicle-Enclosed Oocytes

Methylene Blue Inhibits Cromakalim-Activated K+ Currents in Follicle-Enclosed Oocytes

Cellular and molecular actions of Methylene Blue in the nervous system

Vitamins C and E Modulate Neuronal Potassium Currents

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