Electrical properties of squid axon membrane. II. Effect of partial degradation by phospholipase A and pronase on electrical characteristics.
Passive electrical characteristics of perfused squid axon membrane are investigated. In a previous publication, we reported that the capacitance of intact squid axon membrane is partly frequency dependent. We extended the same measurement to perfused axons. We found that the electrical characteristics of perfused axon membrane are essentially the same as those of intact axons. In this work, we investigated the effects of phospholipase A and pronase on the membrane capacitance. Phospholipase A is known to block the sodium activation and pronase to eliminate the sodium inactivation. Phospholipase A is found to increase the frequency dependent as well as the frequency independent capacitances. Our tentative conclusion is that this enzyme perturbs the lipid structure and decreases its thickness. Pronase is found to increase the frequency dependent capacitance slightly while the capacitance  of the lipid layer remains unaltered. Although voltage clamp data indicate that the pronase disrupts the excitatory mechanism extensively, this enzyme has relatively little effect on the overall membrane capacitance.
D000818:Animals; D001369:Axons / Q000502:physiology*; D049832:Decapodiformes; D004594:Electrophysiology; D066298:In Vitro Techniques; D008566:Membranes / Q000502:physiology; D008959:Models, Neurological; D009419:Nerve Tissue Proteins / Q000502:physiology*; D010740:Phospholipases; D010743:Phospholipids / Q000502:physiology*; D011402:Pronase
D009419:Nerve Tissue Proteins; D010743:Phospholipids; D010740:Phospholipases; D011402:Pronase