Crayfish Electrophysiology Lab Report

Five different external K+ concentrations ranging from 5.4 mM to 60 mM were used to bathe the crayfish preparation. Membrane potential was recorded from the fibres in two muscle groups in the crayfish abdomen —the medial deep extensors and the lateral deep extensors. The solution containing 5.4 mM K+ was standard crayfish saline (van Harreveld’s solution). Resting membrane potentials of the two muscle groups in van Harreveld’s solution were –64.50 ± 6.364 mV in the lateral deep extensors and –67.80 ± 3.271 mV in the medial deep extensors. The resting potentials of these two muscle groups were not significantly different (P = 0.3783 using an unpaired Student’s t-test). No significant difference was observed between the membrane potentials of the lateral and medial deep extensors at any of the external K+ concentrations used in this study.

Depolarization with increase in external K+ concentration was observed in both muscle groups. Membrane potential in the latera...