ABSTRACT
A comparison was made between three different techniques for electrical stimulation of human skeletal muscle: percutaneous stimulation via large aluminum foil electrodes or via ordinary ECG-electrodes and intramuscular stimulation via platinum-coated wires.--The relationship between voltage and duration of the stimulating pulses and the evoked force of contraction is described.--A series of experiments on surgical patients who were curarized showed that these electrical stimulation techniques selectively activate nerve-endings within the muscle, and not the muscle fibres directly.--In a group of male volunteers there were linear relationships between body weight and maximum voluntary contraction force (MVC) of the knee extensors and between body weight and the stimulating voltage needed to produce 50% of MVC.
Subject(s)
Electric Stimulation/methods , Muscle Contraction , Adult , Aged , Body Weight , Female , Humans , Male , Middle AgedABSTRACT
The neuromuscular blocking agent succinylcholine (SCh) has been identified and quantitated in biological material using gas chromatography-mass spectrometry. The bisquaternary ammonium compound SCh is extracted from tissue homogenates or body fluids into dichloromethane as an ion pair with hexanitrodiphenylamine (DPA). The evaporated ion pair residue is demethylated with sodium benzenethiolate to form the corresponding tertiary amine which is identified and quantitated by gas chromatography-mass spectrometry using a glass capillary column coated with SE 52. In the quantitative analysis deuterated SCh is used as internal standard. The instrument is focussed on m/z 58 for demethylated SCh and m/z 62 or 64 for the internal standard. Concentrations as low as 5 ng SCh iodide/g tissue or body fluid are easily detected.
