Effects of repetitive stimulation, veratridine and ouabain on cytoplasmic pH in frog nerve fibres: role of internal Na+

FEBS Letters

Vergun, O.V.²  Valkina, O.N.²  Khodorov, B.I.¹  Turovetsky, V.B.² 

[1] Institute of General Pathology and Pathophysiology, Russian Academy of Medical Sciences, Ul. Baltijskaya 8, 125315 Moscow, Russian Federation;Uljanovsk State Pedagogic Institute, Moscow State University, Moscow, Russian Federation

关键词: Nerve fibre;    Intracellular pH;    Veratridine;    Ouabain;    Stimulation;    [Na+]i;    [Ca2+]i;    intracellular sodium and calcium (respectively) concentrations;    pHi;    internal (cytoplasmic) pH;    HEPES;    4-(2-hydroxyethyl)-1-piperazincethane sulfonic acid;    VER;    veratridine;   

DOI  :  10.1016/0014-5793(93)81686-T

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Changes of cytoplasmic pH (pH_i) in frog nerve fibres during repetitive stimulation have been measured using the fluorescent pH indicator dye fluorescein diacetate (FDA). Under control conditions repetitive (10–50 Hz) stimulation caused only a very small decrease in pH_i (by 0.015–0.06 pH units). Modification of Na⁺ channels by veratridine (VER, 10, μM) greatly increased this stimulus-evoked (SE) internal acidification. Blockade of the Na⁺-K⁺ pump by ouabain (0.5 mM) enhanced the effects VER and prevented pH_i recovery after the termination of repetitive stimulation. A similar inhibition of post-stimulatory recovery of pH_i was observed after replacement of external Na⁺ with Li⁺, which is not accepted by the Na⁺-K⁺ pump instead of Na⁺. These data suggest that SE intracellular acidification in nerves results from or is closely associated with an increase in [Na⁺]_i. Treatments that promote Na⁺ influx and accumulation of Na⁺ inside the fibre enhance reduction of pH_i. Li⁺ can be substituted for Na⁺ in this process.

【 授权许可】

Unknown