VOLTAGE-DEPENDENT POTASSIUM CURRENTS OF SYMPATHETIC PREGANGLIONIC NEURONS IN NEONATAL RAT SPINAL-CORD THIN SLICES

Citation
T. Miyazaki et al., VOLTAGE-DEPENDENT POTASSIUM CURRENTS OF SYMPATHETIC PREGANGLIONIC NEURONS IN NEONATAL RAT SPINAL-CORD THIN SLICES, Brain research, 743(1-2), 1996, pp. 1-10
Citations number
36
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Neurosciences
Journal title
ISSN journal
0006-8993
Volume
743
Issue
1-2
Year of publication
1996
Pages
1 - 10
Database
ISI
SICI code
0006-8993(1996)743:1-2<1:VPCOSP>2.0.ZU;2-H
Abstract
Voltage-dependent potassium currents were analyzed in the visually ide ntified sympathetic preganglionic neurons (SPNs) of neonatal rat spina l cord thin slices by the whole-cell patch-clamp technique. Some of th e SPNs were identified by the presence of retrogradely transported flu orescent dye, DiI, injected into the superior cervical ganglion severa l days prior to experimentation. In a tetrodotoxin (TTX)-containing so lution, a step depolarization from the holding potential of -72 mV gen erated a slow outward current that was suppressed by tetraethylammoniu m (TEA) and by Ca2+-free/2.5 mM Co2+ solution. Ca2+-dependent current consisted of a transient and a sustained components. In a Ca2+-free (s ubstituted with Mg2+) solution with TTX and TEA, a step depolarization from a hyperpolarized potential evoked a transient outward current th at was blocked by 4-aminopyridine (4-AP). A step hyperpolarization evo ked a voltage-dependent inward current, the conductance of which was d ependent not only on the membrane potential, but also on the extracell ular K+ concentration. Tail current analyses revealed that all of thes e currents were carried by K+ ions. These results indicate that SPN po ssesses at least five types of voltage-dependent K+ current, including the delayed rectifier current (I-K), Ca2+-dependent transient Current (I-C), Ca2+-dependent sustained current (I-AHP) A-current (I-A) and i nward rectifying current (I-ir), which may be targets of putative tran smitters released from various descending and segmental inputs impingi ng upon the SPN.