Calcium Action Potentials in the Skeletal Muscle Fibres of the Stick Insect Carausius Morosus
نویسنده
چکیده
The ionic requirements for the generation of action potentials in the ventral longitudinal muscle fibres of the stick insect, Carausius morosus, were investigated. Ca-free Ringer rapidly and reversibly abolished the action potential. In the presence of tetraethylammonium (TEA) ions (to suppress outward currents) the overshoot of the action potential changed 26 mV for a 10-fold change in [Ca]0. The maximum rate of rise of the action potential (measured in TEA Ringer) showed saturation at high [Ca]0. Cobaltous ions (20 HIM) and the organic Ca antagonist D 600 (5 x io" g/ml) reversibly inhibited the action potential; the inhibitory effect of 1 mM-La was irreversible. Barium and strontium, but not magnesium, were able to substitute for calcium as charge carriers. These results suggest that an inward movement of Ca underlies the action potential of Carausius fibres.
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