Background to Neuromuscular Activity 3 Calcium and Magnesium Effects 5 Muscle Characteristics 9 Labile Nature of Neuromuscular Transmission MATERIALS AND METHODS RESULTS AND DISCUSSIONS Perfusion Techniques Control Data #1: Intact Animal Control Data #2: Normal Krebs Perfusion Modified Krebs #1: Decreased [Ca**] and Normal [Mg^] Modified Krebs #2: Decreased [Ca**] and Increased [Mg**] Modified Krebs #3: Decreased [Mg^] and Normal [Ca^^] Modified Krebs #4: Decreased [Mg^] and Decreased [Ca**] 52 Stimulus Threshold Voltages 59 Tetanic Contractions