Myxicola Axons Research Articles

Sodium currents in Myxicola axons. Nonexponential recovery from the inactive state

Sodium currents in Myxicola axons. Nonexponential recovery from the inactive state

Helical structure of Myxicola axoplasm.

Dissection and polarizing microscopy of the giant axon of Myxicola reveal fibrous protein arranged in three levels of helical configurations, all of which may arise from torques about the axes of individual proteins.

Rectification in instantaneous potassium current-voltage relations in Myxicola giant axons.

1. Measurements of the instantaneous K current, under voltage clamp, were obtained using paired de- and hyperpolarizing clamp pulse sequences. The instantaneous potassium current-voltage relations so obtained showed constant field type rectification.2. The zero current potential of the instantaneous K current-voltage relation, when examined as a function of the K concentration, [K](o), behaved like a Nernst concentration cell potential for K. It was concluded that during the generation of the delayed current, the membrane shows substantial selectivity for K.3. The equivalent of the ;Frankenhaeuser-Hodgkin space' in Myxicola was found to be more difficult to load with K ions than in squid. The thickness of the space may be taken as effectively about seven times larger than in squid.4. Myxicola axons were found to show little or no long time constant delayed current inactivation as has been described for squid.5. In high [K](o) a negative steady-state conductance was observed which was predictable from the independence principle with a suitable scaling factor.

Giant axon of Myxicola: some membrane properties as observed under voltage clamp.

A new space-voltage clamped giant (500 to 900 microns) axon preparation is described (Myxicola infundibulum). Normal value for resting and action potentials are 71 and 89 millivolts, respectively. This preparation under voltage clamp exhibits relations between current and voltage like those described for the squid axon. The early inward current component is reduced in a solution with low sodium concentration. This preparation, then, acts in all its essential features like the squid giant axon. Myxicola, however, can be made available the year around and should prove to be an extremely useful preparation for the study of excitable membranes.