Pharmacological relevance of peripheral type benzodiazepine receptors on motor nerve and skeletal muscle.
1. Effects of agonists and antagonists of peripheral and central benzodiazepine receptors (pBZR and cBZR) on neuromuscular transmission were studied in mouse isolated phrenic nerve-diaphragm preparations. 2. Ro5-4864, a pBZR agonist, had no effect on the neuromuscular transmission but increased muscle contractility and antagonized the tetanic fade induced by neostigmine. 3. Ro5-4864 inhibited the regenerative tonic endplate depolarization caused by repetitive stimulation in the presence of neostigmine without affecting the amplitude and decay time of miniature and evoked single endplate potentials. 4. All the effects of Ro5-4864 were shared by PK11195, a pBZR antagonist, but not by clonazepam and flumazenil, a cBZR agonist and antagonist, respectively. 5. It is suggested that peripheral type benzodiazepine receptors modulate presynaptic function and muscle contraction.
Department of Pharmacology, College of Medicine, National Taiwan University, Taipei.
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Chiou
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Chang
D000818:Animals; D001570:Benzodiazepinones / Q000494:pharmacology; D003964:Diaphragm / Q000187:drug effects / Q000294:innervation; D004558:Electric Stimulation; D004594:Electrophysiology; D005260:Female; D005442:Flumazenil / Q000494:pharmacology; D058787:GABA-A Receptor Antagonists; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008839:Microelectrodes; D009045:Motor Endplate / Q000187:drug effects; D009046:Motor Neurons / Q000187:drug effects*; D009119:Muscle Contraction / Q000187:drug effects; D009132:Muscles / Q000187:drug effects / Q000294:innervation*; D009388:Neostigmine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D010791:Phrenic Nerve / Q000187:drug effects; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D001570:Benzodiazepinones; D058787:GABA-A Receptor Antagonists; C028513:4'-chlorodiazepam; D009388:Neostigmine; D005442:Flumazenil; D005680:gamma-Aminobutyric Acid