INVESTIGATION OF GATING CURRENTS IN SKELETAL MUSCLE

本文将采用三微电极电压钳技术进行研究

The three microelectrode voltage clamp technique will be used to investigate membrane charge movement (gating current) in frog skeletal muscle fibers. In addition, the intracellular free Ca 2 ion concentration change will be measured during step depolarizations using the metallochromic indicator dye arsenazo III. The dye will be injected iontophoretically into fibers in the cutaneous pectoris muscle. A 50 microsm diameter spot of light from a tungsten-halogen lamp will be focused on the point of voltage control. Changes in light transmittance will be measured at three wavelengths using a compound microscope, beam splitters and interference filters. A microscope photometer system with the required sensitivity has been constructed and tested. The objective of the research is to test the hypothesis that membrane charge movement in muscle is a gating current for Ca 2 ion release from the sarcoplasmic reticulum. The hypothesis will be tested by examining whether charge movement and the Ca 2 ion transient behave in parallel during a variety of experimental conditions. For example, the voltage dependence, subthreshold response, threshold behavior and the response to prolonged depolarization will be examined.