Presynaptic action of barbiturates in the frog spinal cord.

نویسنده

  • R A Nicoll
چکیده

The action of pentobarbital on primary afferents of the isolated frog spinal cord was analyzed with sucrose gap and intracellular recordings techniques. Pentobarbital in concentrations generally considered to be in the anesthetic range greatly prolonged presynaptic inhibition and also depolarized primary afferents. The depolarization was accompanied by an increase in excitability and resulted from activation of gamma-aminobutyric acid receptors, possibly by a direct action on these receptors, since the depolarization was reversibly blocked by gamma-aminobutyric acid, but not by glycine, antagonists, and magnesium ions. Furthermore, dorsal root ganglion cells exhibited a reduced sensitivity to both gamma-aminobutyric acid and pentobarbital after a "desensitizing" dose of gamma aminobutyric acid. The prolongation of presynaptic inhibition and the activation of gamma-aminobutyric acid receptors on primary afferents by pentobarbital should act to reduce the amount of transmitter released from the first synapse in sensory pathways.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Comparative electron microscopy of synapses in the vertebrate spinal cord.

Synapses with a cleft with ' thickened' membranes and presynaptic vesicles and mitochondria occur commonly throughout the grey matter of the spinal cord of goldfish, frog and various mammals studied. Such synapses are generally thought to have a chemical mode of transmission. The absence or rare occurrence of presynaptic neurofilaments in fish and frog accounts for the failure to detect boutons...

متن کامل

Compound Action Potential of Isolated Spinal Cord: A Biophysical Analysis to Address Activity of Individual Fibers Following Contusion Injury

Compound action potential (CAP) of spinal cord represents valuable properties of neural fibers including excitability, rate of myelination and membrane integrity. These properties are measured using amplitude, latency and area under curve of CAPs recorded from spinal cord. Here, the isolated spinal cord was set in a double sucrose gap (DSG) chamber and its response to intracellular stimulation ...

متن کامل

Sites and mechanisms of action of lidocaine upon the isolated spinal cord of the frog.

The sites of action of lidocaine on the responses evoked by stimulation of lateral column (LC) and dorsal root (DR) were studied in the isolated, intra-arterially perfused spinal cord of the bullfrog. When the ventral root volley produced by stimulation was abolished by lidocaine, the presynaptic focal potential was almost unchanged. Intracellular recordings from motoneurons clearly demonstrate...

متن کامل

Barbiturate reduction of calcium-dependent action potentials: correlation with anesthetic action.

Calcium-dependent action potentials were recorded from mouse spinal cord neurons in primary dissociated cell culture following addition of the potassium channel blockers tetraethylammonium ion and 3-aminopyridine. The pharmacologically active barbiturates, pentobarbital and phenobarbital, but not the pharmacologically inactive barbiturate, barbituric acid, produced reversible, dose-dependent re...

متن کامل

Selective Modulation of Chemical Transmission at a Dual-Action Synapse (with Special Reference to Baclofen)

Monosynaptic, electrical-chemical EPSPs were produced in individual motoneurons of the isolated frog spinal cord by intracellular stimulation of single primary afferents. This preparation was used to assess the relationship between the modulation of chemical synaptic transmission and presynaptic invasion. It was found that at dual-action synapses Baclofen selectively depressed chemical transmis...

متن کامل

ذخیره 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 نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • Proceedings of the National Academy of Sciences of the United States of America

دوره 72 4  شماره 

صفحات  -

تاریخ انتشار 1975