The actions of 5-hydroxytryptamine on the membrane of putative sympatho-excitatory neurones in the rostral ventrolateral medulla of the adult rat in vitro.
Intracellular recordings were obtained in vitro from neurones lying within the rostral ventrolateral medulla of the adult rat. Neurones could be classified into three groups: silent neurones, irregularly firing neurones which had a regular pattern of action-potential generation. Membrane hyperpolarization of regularly firing neurones failed to reveal underlying EPSPs or disrupt the regular pattern of action-potential generation. Superfusion of a high Mg2+, low Ca2+ aCSF did not abolish action-potential generation but the regular pattern of firing of these neurones was lost. 5-Hydroxytryptamine evoked a slow concentration-dependent hyperpolarization in both spontaneously active and silent neurones, accompanied by a decrease in cell-input resistance. This study has provided further evidence for pacemaker-like neurones within the RVLM and for the modulation of these neurones by 5-hydroxytryptamine.
Lewis
D I
DI
Department of Physiology, Medical School, University of Birmingham, UK.
Coote
J H
JH
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects*; D004594:Electrophysiology; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology* / Q000187:drug effects; D009474:Neurons / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000494:pharmacology*; D013564:Sympathetic Nervous System / Q000166:cytology* / Q000187:drug effects
D012701:Serotonin; D008274:Magnesium; D002118:Calcium