['a', ';', 'U.', 'PROPOSAL', 'A', '0500/3050.05', 'RL33', '(RY', 'A6:', '(KE)', 'PAGE:', '3-1', '3.', 'INTRODUCTION', 'The', 'striated', 'muscle', 'of', 'the', 'isolated', 'Phrenic', 'nerve-diaphragm', 'Preparation', 'contracts', 'when', 'the', 'phrenic', 'nerve', 'is', 'electrically', 'stimulated.', 'The', 'indirect', 'stimulation', 'provides', 'the', 'possibility', 'to', 'study', 'the', 'effects', 'of', 'substances', 'on', 'the', 'neuromuscular', 'trans-', 'mission,', 'The', 'physiological', 'transmitter', 'in', 'motoneurons', 'is', 'acetylcholine.', 'Acetylcholine,', 'added', 'in', 'low', 'concentrations', 'to', 'the', 'incubation', 'medium,', 'increases', 'the', 'force', 'of', 'contraction', 'of', 'the', 'diaphragm,', 'whereas', 'at', 'higher', 'concentrations', 'it', 'gradually', 'inhibits', 'the', 'contraction.', 'This', 'effect', 'can', 'also', 'be', 'achieved', 'by', 'using', 'acetyl-', 'cholinesterase', 'inhibitors.', 'Nicotine,', 'besides', 'its', 'stimulating', 'and', 'inhibiting', 'effects', 'on', 'postsynaptic', 'ganglionic', 'receptors,', 'also', 'acts', 'on', 'the', 'acetylcholine', 'receptors', 'of', 'the', 'motor', 'endplate.', 'Just', 'as.', 'acetylcholine,', 'in', 'low', 'concentrations', 'it', 'increases', 'and', 'at', 'higher', 'concentrations', 'it', 'decreases', 'the', 'force', 'of', 'contraction,', 'when', 'the', 'phrenic', 'nerve', 'is', 'stimulated', 'by', 'single', 'electrical', 'impulses.', 'There', 'are', '2', 'types', 'of', 'neuromuscular', 'blocking', 'substances,', 'the', 'competitive', 'blocking', 'substances', 'such', 'as', 'tubocurarine', '(used', 'here', 'as', 'reference', 'substance)', 'and', 'the', 'depolarizing', 'blocking', 'substances', 'such', 'as', 'suxamethonium', 'and', 'decamethonium.', '88eSPss20e']