Inspiratory-activated and inspiratory-inhibited airway vagal preganglionic neurons in the ventrolateral medulla of neonatal rat are different in intrinsic electrophysiological properties.
This study investigates the firing properties of the inspiratory-activated and inspiratory-inhibited airway vagal preganglionic neurons located in the external formation of the nucleus ambiguus. The results showed that inspiratory-activated and inspiratory-inhibited neurons are distributed with different density and site preference in this area. Inspiratory-inhibited neurons exhibit significantly more positive resting membrane potential, more negative voltage threshold and lower minimal current required to evoke an action potential under current clamp. The afterhyperpolarization in inspiratory-activated neurons was blocked by apamin, a blocker of the small-conductance Ca(2+)-activated K(+) channels; and that in inspiratory-inhibited neurons by charybdotoxin, a blocker of the large-conductance Ca(2+)-activated K(+) channels. Under voltage clamp, depolarizing voltage steps evoked tetrodotoxin-sensitive rapid inward sodium currents, 4-aminopyridine-sensitive outward potassium transients and lasting outward potassium currents. 4-Aminopyridine partially blocked the lasting outward potassium currents of inspiratory-activated neurons but was ineffective on those of inspiratory-inhibited neurons. These findings suggest that inspiratory-activated and inspiratory-inhibited neurons are differentially organized and express different types of voltage-gated ion channels.
The State Key Laboratory of Medical Neurobiology and Institute of Brain Sciences, Fudan University Shanghai Medical College, China.
Yonghua
Y
Chen
Lili
L
Hou
Xujiao
X
Zhou
Dongying
D
Qiu
Wenjun
W
Yuan
Lei
L
Zhu
Jijiang
J
Wang
D000818:Animals; D000831:Animals, Newborn; D001030:Apamin / Q000494:pharmacology; D001339:Autonomic Fibers, Preganglionic / Q000187:drug effects / Q000502:physiology*; D001933:Brain Stem / Q000502:physiology; D018999:Charybdotoxin / Q000494:pharmacology; D055724:Electrophysiological Phenomena; D005456:Fluorescent Dyes; D007002:Hypoglossal Nerve / Q000502:physiology; D066298:In Vitro Techniques; D008526:Medulla Oblongata / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers / Q000494:pharmacology; D024681:Potassium Channels, Calcium-Activated / Q000187:drug effects / Q000502:physiology; D051381:Rats; D015656:Respiratory Mechanics / Q000502:physiology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology; D014132:Trachea / Q000294:innervation / Q000502:physiology; D014630:Vagus Nerve / Q000187:drug effects / Q000502:physiology*
D005456:Fluorescent Dyes; D026902:Potassium Channel Blockers; D024681:Potassium Channels, Calcium-Activated; D018999:Charybdotoxin; D001030:Apamin