Scorpion venom (Leiurus quinquestriatus) elicits accumulations of inositol phosphates and cyclic AMP in guinea pig cortical synaptoneurosomes

FEBS Letters

Gusovsky, Fabian¹  Daly, John W.¹ 

[1] Laboratory of Bioorganic Chemistry, Bldg 4, Room 212, National Institute of Arthritis, Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA

关键词: Na+ channel;    Tetrodotoxin;    cyclic AMP;    Phosphatidylinositol;    (Brain);    Inositol phosphate;   

DOI  :  10.1016/0014-5793(86)81234-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Scorpion (Leiurus quinquestriatus) venom (ScV) stimulated accumulations of cyclic AMP and turnover of phosphatidylinositol in guinea pig cortical synaptoneurosomes. The concentrations of ScV that were necessary to increase cyclic [³H]AMP accumulation were lower than those required to stimulate formation of [³H]inositol phosphates from phosphatidylinositol. In the presence of 10 μM 2-chloroadenosine, ScV induced a dose-dependent synergistic accumulation of cyclic AMP with an EC₅₀ value that was comparable to the EC₅₀ required for stimulation of phosphatidylinositol turnover. Tetrodotoxin partially inhibited cyclic AMP accumulations elicited by ScV indicating that at least part of such responses are due to activation of voltage-dependent sodium channel. Tetrodotoxin virtually completely blocked formation of inositol phosphate stimulated by ScV. High concentrations of Mg²⁺ (30 mM) did not block responses to ScV indicating that release of neurotransmitters was not involved. Membrane potential changes could not be detected at concentrations of ScV that triggered the biochemical responses. Stimulation of phosphatidylinositol turnover by ScV appears to depend on an increase in influx of Na⁺ in synaptoneurosomes, presumably due to slowing of the inactivation of voltage-dependent sodium channels by α-scorpion toxin, a component of ScV. At least in part, the stimulation of cyclic AMP accumulation by ScV correlates with increases in phosphatidylinositol turnover.

【 授权许可】

Unknown