CONICET | Buscador de Institutos y Recursos Humanos

Título: Temporal evolution of neuritic calcium transients in a leech passive neuron Autores: Sung Min Yang y Lidia Szczupak Resumen The propagation of electrical signals in neurons without action potentials (passive neurons) are primarily controlled by the passive mode of transmission, although at present there are many evidences of the presence of active conductances (i.e., voltage-dependent) on their dendrites and of their effects on the integration of signals. The NS neurons are nonspiking cells, present as pairs in each midbody ganglion of the leech nervous system, which display a very extensive arborization. They regulate the action potential frequency of all the described excitatory motoneurons and receive sensory inputs. This regulation is carried out by means of electrical synapses, rather than through gradual chemical synapses. Previous results indicate that NS neurons respond to electrical stimulation with a spike-like event. This phenomenon is basically supported by low-threshold calcium channels and TEA-sensitive potassium channels. With the aim of studying the spatial and temporal distribution of the intracellular calcium transient in the neurites of this cell which accompanies that response, we used simultaneous measurement of calcium imaging and electrophysiological recordings in the soma. Neurons were loaded with the calcium sensitive fluorescent dye Calcium Green-5N and recorded by a confocal microscope, and the spike-like event was evoked by current injection in the soma. The results suggest that the calcium channels are distributed over the whole extension of the primary neurites and the calcium transients have homogeneous kinetic properties. In addition, the entry of Ca2+ into the NS neuron seems to be simultaneous in entire studied processes.