Magnesium is the second most abundant intracellular cation and presents in all living organisms. Magnesium is also regarded as an important element for neuromuscular functions and the efficiency of energy metabolism. Some studies have reported that prolonged and submaximal exercise induces hypomagnesaemia, whereas short-term, high-intensity exercise induces hypermagnesaemia. Whether exercise results in increased or decreased magnesium concentrations remains controversial. The aim of proposal is to develop auto-blood sampling method and microdialysis technique to detect the dynamic changes of glucose, lactate, pyruvate and magnesium levels of blood and brain in conscious and freely moving animals during exercise. Sprague-Dawley rats are pretreated with normal saline (control group) and magnesium sulfate (90 mg·kg-1, intraperitoneal injection) before a 15 min forced swimming. The dialysate and whole blood samples are continuously and simultaneously collected by the both microdialysis system and automated blood sampling system (automated blood sampler, Instech ABS). The dynamic profiles of glucose, lactate, pyruvate and magnesium before, during and after swimming are determined by microdialysis analyzer (CMA/600) and flame atomic absorption spectrometer (Perkin-Elmer Model 5100 FAAS). These data will provide dynamic information of central and peripheral magnesium as well as energy metabolites during exercise performance; moreover, the relationship of exercise, magnesium and energy metabolites levels will be further studied.
