CONSTANT TURNOVER OF ARACHIDONIC-ACID AND INHIBITION OF A POTASSIUM CURRENT IN APLYSIA GIANT-NEURONS

被引:9
作者
CARLSON, RO [1 ]
LEVITAN, IB [1 ]
机构
[1] BRANDEIS UNIV, GRAD DEPT BIOCHEM, WALTHAM, MA 02254 USA
关键词
Aplysia; arachidonic acid; eicosanoids; inward rectifier; phorbol ester; potassium current; protein kinase C;
D O I
10.1007/BF01868465
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Steady-state currents at hyperpolarized membrane potentials were studied in the homologous giant neurons, LP1 and R2, of Aplysia using two-electrode voltage clamp. Nearly half of the steady-state current at voltages more hyperpolarized than -70 mV had characteristics similar to the inwardly rectifying potassium current (IR) described previously in Aplysia neurons. The pharmacological agents 4-bromophenacylbromide, indomethacin, and the phorbol ester, 12-O-tetradecanoyl-phorbol-13-acetate were found to modulate IR. IR was stimulated with BPB and indomethacin and inhibited with TPA. These agents altered IR by a mechanism independent of cAMP, which can also modulate IR. The effects of these modulators are consistent with their actions on arachidonic acid (AA) metabolism in Aplysia nervous system, suggesting AA may constitutively inhibit IR. When ganglia were perfused for 12 hr with medium containing BSA to absorb extracellular fatty acids, IR was increased nearly twofold. This increase was partially inhibited by addition of AA to the perfusion medium, and completely inhibited by pretreatment of ganglia with BPB. Although no direct effect of shortterm exposure to exogenous AA was observed, long term exposure to exogenous AA and several other unsaturated fatty acids was accompanied by a decrease in IR. © 1990 Springer-Verlag New York Inc.
引用
收藏
页码:261 / 272
页数:12
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