ABSTRACT
Electrocytes from the electric organ of Electrophorus electricus exhibited sodium action potentials that have been proposed to be repolarized by leak currents and not by outward voltage-gated potassium currents. However, patch-clamp recordings have suggested that electrocytes may contain a very low density of voltage-gated K(+) channels. We report here the cloning of a K(+) channel from an eel electric organ cDNA library, which, when expressed in mammalian tissue culture cells, displayed delayed-rectifier K(+) channel characteristics. The amino-acid sequence of the eel K(+) channel had the highest identity to Kv1.1 potassium channels. However, different important functional regions of eel Kv1.1 had higher amino-acid identity to other Kv1 members, for example, the eel Kv1.1 S4-S5 region was identical to Kv1.5 and Kv1.6. Northern blot analysis indicated that eel Kv1.1 mRNA was expressed at appreciable levels in the electric organ but it was not detected in eel brain, muscle, or cardiac tissue. Because electrocytes do not express robust outward voltage-gated potassium currents we speculate that eel Kv1.1 channels are chronically inhibited in the electric organ and may be functionally recruited by an unknown mechanism.
Subject(s)
Electric Organ/chemistry , Electric Organ/physiology , Electrophorus/metabolism , Membrane Potentials/physiology , Potassium Channels, Voltage-Gated , Potassium Channels/chemistry , Potassium Channels/physiology , Potassium/metabolism , Amino Acid Sequence , Animals , CHO Cells , Cloning, Molecular , Cricetinae , Cricetulus , Electrophorus/genetics , Kv1.1 Potassium Channel , Molecular Sequence Data , Organ Specificity , Potassium Channels/genetics , Rats , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Sequence Homology, Amino Acid , Species Specificity , Tissue Distribution , Xenopus laevisSubject(s)
S100 Proteins/metabolism , Schwann Cells/metabolism , Adult , Animals , Biomarkers , Cells, Cultured , Humans , Mice , Mice, Inbred ICR , Schwann Cells/cytologyABSTRACT
Specificity of reinnervation after a peripheral nerve lesion has given rise to considerable controversy. As a contribution to solving this issue we have evaluated the specificity of reinnervation of the peroneal nerve after a complete transection of the sciatic nerve repaired with an 8 mm silicone tube, leaving a 4 mm gap between the nerve stumps. Our findings reveal unspecificity of reinnervation of the distal peroneal branch. This lack of specificity is shown by a random distribution of fibers originating from both proximal branches at the level of the tube and at distal peroneal and tibial branches, argue against specificity of regeneration in this model.
