Can barium support the release of acetylcholine by nerve impulses?
نویسنده
چکیده
Conventional electrophysiological techniques were used to study the effects of Ba on the release of acetylcholine (ACh) from frog motor nerve terminals. Equimolar substitution of Ba for Ca eliminated end-plate potentials (e.p.ps) without a corresponding decline in the amplitude of the nerve terminal action potential. Miniature end-plate potentials (m.e.p.ps) were readily detectable in Ba solutions despite a depolarized muscle membrane. Studies on the e.p.p. in curarized preparations bathed with different concentrations of Ca and Ba suggest that Ba may compete with Ca in the process by which depolarization of the nerve terminal leads to the release of ACh. Repetitive nerve stimulation at 1 Hz in Ba solutions caused 5-20 fold increases in m.e.p.p. frequencies (7 experiments). Stimulation of Ba-bathed preparations at 10 Hz elevated m.e.p.p. frequencies to very high levels that could not be measured accurately (''100/s). It is suggested that the asynchronous discharge of m.e.p.ps produced by repetitive nerve stimulation is the electrophysiological correlate of the evoked ACh outflow in Ba solutions detected previously by bioassay of ther perfusion fluid.
منابع مشابه
P 25: The Facilitatory Action of Snake Venom Phospholipase A2 Neurotoxins by Which Increase the Release of Acetylcholine, May Improve Alzheimer\'s Disease Symptoms
Introduction: In a serious brain disorder like Alzheimer's disease, the levels of acetylcholine (Ach) drop significantly. The gradual death of cholinergic brain cells leads to a profound loss of memory and learning ability. Acetylcholine is the chemical messenger that sends messages from one neuron to another in the area of the brain used for memory. Many of the current medications act to enhan...
متن کاملENDOGENOUS RELEASE OF OPIATES BY REPETITIVE ELECTRICAL FIELD STIMULATION IN THE GUINEA-PIG AND RAT ILEAL LONGITUDINAL MUSCLE
The effect of repetitive electrical field stimulation and the response of the guinea-pig and rat ileal longitudinal muscle to single pulse stimulations was examined. Single pulse field stimulation produced twitch contraction which was inhibited by repetitive field stimulation (10 Hz, 40V, 0.5 msec for 5 m). This inhibition was largely, though never completely, reversed by naloxone. Contrac...
متن کاملEffects of Black Scorpion Androctonus crasicuda Venom on Striated Muscle Preparation in vitro.
Effects of venom from black scorpion Androctonus crasicuda (AC) were determined on isolated chick biventer cervices nerve-muscle and mouse hemidiaphragm preparations using twitch tension method. The isolated nerves were stimulated by electrical stimulator and response to each stimulus was recorded. The venom mainly acted prejunctionally to facilitate neuromuscular activity due to an increase in...
متن کاملEffects of Black Scorpion Androctonus crasicuda Venom on Striated Muscle Preparation in vitro.
Effects of venom from black scorpion Androctonus crasicuda (AC) were determined on isolated chick biventer cervices nerve-muscle and mouse hemidiaphragm preparations using twitch tension method. The isolated nerves were stimulated by electrical stimulator and response to each stimulus was recorded. The venom mainly acted prejunctionally to facilitate neuromuscular activity due to an increase in...
متن کاملAxon/Schwann-cell relationships in the giant nerve fibre of the squid.
This communication summarizes the experimental evidence obtained in the giant nerve fibre of the tropical squid Sepioteuthis sepioidea, on the nature of the mechanism responsible for the long-lasting effects of axonal excitation on the membrane potential of the Schwann cell. In these nerve fibres the propagation of a train of nerve impulses by the axon is followed by a prolonged hyperpolarizati...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- British journal of pharmacology
دوره 59 1 شماره
صفحات -
تاریخ انتشار 1977