ISSN:
1432-1351
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary During in vitro experiments, different electrophysiological properties of single electrocytes were demonstrated in 3 portions (abdominal, intermediate, and tail) of the electric organ of the weakly electric fishGymnotus carapo. Membrane potentials were measured with intracellular microelectrodes, while action currents were recorded by means of extracellular micropipettes facing the electrogenic surfaces (rostral and caudal). The nerve supplies to the caudal and rostral faces of abdominal, doubly innervated electrocytes (DIEs) could be independently stimulated, while this separation is not possible in other portions of the electric organ (EO). At the abdominal level, the rostral faces generate only postsynaptic potentials; the caudal faces give rise to action potentials. When the activation of both faces is properly timed, the action currents recorded at the rostral face reproduce quite faithfully the waveform generated by the whole EO, including the duration of the different phases. Within the intermediate portion, neural activation of DIEs (tube 1 electrocytes) was performed via the posterior electromotor nerve. An action potential originates at the rostral face, invading secondarily the caudal membrane. In the most caudal 30% of the EO, the electrocytes of tube 1 are singly innervated on their caudal faces. Consequently, when activated via the posterior electromotor nerve, the caudal membrane gives rise to an action potential, which secondarily invades the rostral face. This electrical behavior is also observed in electrocytes belonging to tubes 2, 3, and 4 (caudally innervated) all along the EO. The number and distribution of spinal roots providing innervation to single DIEs at different levels of the EO were determined by electrophysiological methods.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00619354
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