Analysis of a decreased Na+ conductance by tumor necrosis factor in identified neurons of Aplysia kurodai

✍ Scribed by Dr. M. Sawada; N. Hara; T. Maeno

• Book ID: 102911972
• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 615 KB
• Volume: 28
• Category: Article
• ISSN: 0360-4012
• DOI: 10.1002/jnr.490280403

✦ Synopsis

Abstract

The ionic mechanism of the effect of extracellularly ejected recombinant human tumor necrosis factor‐alpha (rhTNF‐α) on the membrane of identified neurons R9 and R10 of Aplysia kurodai was investigatedwith conventional voltage‐clamp, micropressure ejection, and ion substitution techniques. Micropressureejected rhTNF caused a marked hyperpolarization in the undamped neuron. Clamping the same neuron at its resting potential level (–60 mV) and reejecting rhTNF‐α with the same doseproduced a slow outward current [I~o~(TNF)] associated with a decrease in input membrane conductance. I~o~(TNF) was decreased by depolarization and increased by hyperpolarization. The extrapolated reversal potential of I~o~}(TNF) was approximately +10 mV. Ion substitution and pharmacological experiments suggest that I}~o~(TNF) in identified neurons R9 and R10 of A. kurodai is due to a decreased Na^+^ conductance but not due to an activation of the Na^+^ ‐K^+^ Pump. Our results demonstrate that the immunomodulator TNF can act directly on the nervous system as well as on the immune system.