Functional role of low-voltage-activated dihydropyridine-sensitive Ca channels during the action potential in adult rat sensory neurones.

Ferroni A, Galli A, Mazzanti M
Pflugers Arch. 1996 431 (6): 954-63

PMID: 8927515 · DOI:10.1007/s004240050091

Neuronal cell firing is crucial to nerve-nerve communication. The ability to produce consecutive action potentials is related to the activation of inward currents after each upstroke. If fast Na current is indeed responsible for the overshoot, it is still unclear which current drives membrane voltage to the Na threshold. In this study we present evidence that in adult rat sensory neurones a dihydropyridine-sensitive Ca channel exists in addition to the well characterized L-type, or high-threshold Ca channel. During stimulated action potential trains, L-type Ca channels open during the excitation wave, whereas activity of the other dihydropyridine-sensitive Ca channel was observed primarily between action potentials. This second Ca pathway shows remarkably long openings at negative potentials after a series of positive prepulses. The nerve action potential and the repetitive firing work as a physiological Ca channel facilitation mechanism. Therefore, we suggest that this novel Ca conductance provides inward current, between two consecutive action potentials, able to modulate the frequency of neuronal bursts.

MeSH Terms (13)

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester Action Potentials Animals Calcium Channel Agonists Calcium Channels Dihydropyridines Electric Conductivity Electrophysiology Ganglia, Spinal In Vitro Techniques Membrane Potentials Neurons, Afferent Rats

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