Acetylcholine (ACh), released from axonal terminals of motor neurons in neuromuscular junctions regulates the efficacy of neurotransmission through activation of presynaptic nicotinic and muscarinic autoreceptors. Receptor-mediated presynaptic regulation could reflect either direct action on exocytotic machinery or modulation of Ca2+ entry and resulting intra-terminal Ca2+ dynamics. We have mea...

Excessive inflammation and tumor-necrosis factor (TNF) synthesis causes morbidity and mortality in diverse human diseases including endotoxaemia, sepisis, rheumatoid arthritis and inflammatory bowel diseases. Highly conserved, endogenous mechanisms normally regulate the magnitude of innate responses and prevent excessive inflammation. The release of system, through the vagus nerve, can inhibit ...

In this study, effects of Buthus eupeus venom on chick biventer cervices nerve-muscle preparation were investigated by twitch tension method. The venom, at 1.3 ?g/ml, increased contractile responses in indirect stimulations. These effects were milder in direct muscle stimulations. It also caused significant enhancement in postjunctional sensitivity as assessed by responses to exogenous acetylch...

Objectives At the completion of this course, the reader should be able to: 1. Identify the anatomy and physiology of acetylcholine and nicotinic acetylcholine receptors. 2. Describe the method of action of neuromuscular blocking drugs. 3. Describe the available methods for monitoring recovery from neuromuscular blockade. 4. Discuss the options available to reverse neuromuscular blockade and the...

Four critically positioned amino acids on each of the alpha, beta, delta, and gamma subunits of the Torpedo nicotinic acetylcholine receptor are determinants of channel conductance. Our results show that the gamma and epsilon subunits of Xenopus muscle receptors are identical at all four positions, despite the fact that alpha 2 beta delta epsilon receptors have a 50% greater conductance than al...

Nicotinic acetylcholine receptors (nAChRs) are a diverse family of neurotransmitter-gated ion channels which contain five transmembrane subunits arranged around a central pore. Distinct receptor subtypes are expressed at the vertebrate skeletal neuromuscular junction, in mechanosensory cells and within the central and peripheral nervous systems. A total of 17 nAChR subunits (alpha1-alpha10, bet...

Expression of adult-type nicotinic acetylcholine receptors at the neuromuscular junction is thought to result from selective induction of their genes in endplate-associated nuclei due to local neurotrophic control. However, denervation studies indicate that endplate-specific expression can be maintained in the absence of the nerve. We investigated the role played by the basal lamina in this exp...

Autoregulation of synaptic transmission in the nervous system is one of the homeostatic processes by which the transmission can be regulated according to varied physiological conditions. The neuromuscular cocultures of Xenopus laevis embryos were used to investigate the role of presynaptic nicotinic receptors in the autoregulation of developing motoneurons. The bath application of 2 microM nico...

Studies of the regulation of tyrosine phosphorylation at the neuromuscular junction during development and following denervation suggest that tyrosine phosphorylation of the nicotinic acetylcholine receptor is regulated by neuronal innervation of muscle. The finding that agrin, a neuronally derived extracellular matrix protein also induces tyrosine phosphorylation of the nicotinic receptor, sug...