Experiments were performed to determine the role of acetylcholine (ACh) in neuromuscular transmission in the heart of the leech Hirudo medicinalis. Superfused or iontophoretically applied ACh rapidly depolarized both isolated heart muscle cells and muscle cells in isolated hearts in a dose-dependent manner. the depolarization was associated with a conductance increase of the muscle membrane tha...

Congenital myasthenic syndromes (CMS) are rare and heterogeneous genetic diseases characterized by compromised neuromuscular transmission and clinical features of fatigable weakness; age at onset, presenting symptoms, distribution of weakness, and response to treatment differ depending on the underlying molecular defect. Mutations in one of the multiple genes, encoding proteins expressed at the...

Nicotinic receptor (nAChR) subtypes involved in preand postjunctional actions underlying tetanic fade were studied in rat phrenic-nerve hemidiaphragms. We investigated the ability of subtype-specific nAChR antagonists to depress nerve-evoked contractions and [H]-acetylcholine ([H]-ACh) release. Muscle tension was transiently increased during brief high frequency trains (50 Hz for 5 sec). The ra...

Equilibrium conditions of neurotransmitter concentration and receptor binding are never achieved during synaptic transmission at the neuromuscular junction. Thus, it is important to determine the binding kinetics of drugs that act this synapse. Previous determinations of the dissociation rate of (+)-tubocurarine have produced inconsistent results ranging from 0.1 to 4000/s. Here, we used a dire...

Reversible acetylcholinesterase inhibitors are used as first-line treatment for myasthenia gravis. They improve symptoms by increasing concentration of acetylcholine at the neuromuscular junction and stimulating nicotinic receptors. Serious bradyarrhythmias can occur from muscarinic stimulation in heart, which in rare cases may progress to asystole. These patients can initially be managed with ...

advances, it's now possible to get an in-depth look at cellular processes. These images show three-dimensional Monte Carlo simulations of synaptic variability at the vertebrate neuromuscular junction. The simulations were created using the MCELL computer program. In the image at top right, highly convoluted synaptic membranes have been reconstructed; the cleft face of the muscle membrane is lig...

Crude extracts and three isolated alkaloids from Erythrina mulungu plants have shown anxiolytic effects in different animal models. We investigated whether these alkaloids could affect nicotinic acetylcholine receptors and if they are selective for different central nervous system (CNS) subtypes. Screening experiments were performed using a single concentration of the alkaloid co-applied with a...

introduction:yasthenia gravis is an autoimmune disorder resulting from a decreased number of active acetylcholine receptors at the neuromuscular junction. thymectomy is one of its current treatments. due to sensitivity of myasthenic patients to non-depolarizing muscle relaxants and also the interaction of this medication with anti-cholinestrase drugs, determining the dosage of non-depolarizing ...

Hybridoma techniques have been used to generate monoclonal antibodies to an antigen concentrated in the basal lamina at the Xenopus laevis neuromuscular junction. The antibodies selectively precipitate a high molecular weight heparan sulfate proteoglycan from conditioned medium of muscle cultures grown in the presence of [35S]methionine or [35S]sulfate. Electron microscope autoradiography of ad...