Schofield G G, Weight F F, Ikeda S R
Section of Electrophysiology, National Institute on Alcohol Abuse and Alcoholism, Rockville, MD 20852.
Eur J Pharmacol. 1988 Feb 16;147(1):39-48. doi: 10.1016/0014-2999(88)90631-0.
The effects of the alkaloid pumiliotoxin-B were investigated on neurons from bullfrog paravertebral ganglia using current-clamp techniques. Pumiliotoxin-B (2 microM) induced repetitive action potential discharge or bursting pacemaker activity in response to a single stimulus. The toxin had no significant effect on the mean resting potential or action potential characteristics of single action potentials evoked prior to the action potential discharge onset. During the action potential discharge, action potential threshold and afterhyperpolarization amplitude were decreased. In the presence of pumiliotoxin-B, single action potentials were followed by a depolarizing afterpotential. Pumiliotoxin-B still induced action potential discharge in Ca2+-free or Cd2+-containing solutions. Brief superfusion with a Na+-free or tetrodotoxin-containing solution abolished the pumiliotoxin-B-induced action potential discharge prior to the blockade of directly elicited single action potentials. These solutions decreased or abolished the depolarizing afterpotential. Pumiliotoxin-B increases membrane excitability and can induce a stimulation-dependent action potential discharge which appears to result from a tetrodotoxin-sensitive Na+-sensitive potential.
采用电流钳技术研究了生物碱蟾毒灵 - B对牛蛙椎旁神经节神经元的影响。蟾毒灵 - B（2微摩尔）对单个刺激产生重复动作电位发放或爆发性起搏活动。该毒素对动作电位发放开始前诱发的单个动作电位的平均静息电位或动作电位特征无显著影响。在动作电位发放期间，动作电位阈值和超极化后电位幅度降低。在蟾毒灵 - B存在的情况下，单个动作电位之后会出现去极化后电位。蟾毒灵 - B在无钙或含镉溶液中仍能诱发动作电位发放。用无钠或含河豚毒素的溶液短暂灌流，在直接诱发的单个动作电位被阻断之前，就消除了蟾毒灵 - B诱发的动作电位发放。这些溶液降低或消除了去极化后电位。蟾毒灵 - B增加膜兴奋性，并能诱发刺激依赖性动作电位发放，这似乎是由河豚毒素敏感的钠敏感电位引起的。
