title: Histamine depolarizes rat medial vestibular nucleus neurons recorded intracellularly in vitro.
abstract: The effects of histamine (HA) on the resting membrane potential and input resistance of rat medial vestibular nucleus (MVN) neurons were investigated using intracellular recording techniques from a submerged brain slice preparation. The exogenous application of HA predominantly produced a concentration-dependent membrane depolarization and induction of action potential firing. The depolarization exhibited a rapid onset, a slow recovery, and usually occurred in the absence of any apparent change in conductance. These effects of HA could be mimicked by the H2-agonist impromidine and were reversibly blocked by the H2-antagonist cimetidine. Tetrodotoxin (TTX) or low calcium/high magnesium-containing media failed to block completely the HA-induced depolarization supporting a direct postsynaptic receptor mediated action of HA. The diminished HA-induced depolarization observed following pretreatment with TTX cannot exclude an additional presynaptic action by HA. The present findings reveal that HA exerts a novel direct excitation of rat MVN neurons through an H2-receptor.
authors: Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston 77550.
authors: K D
authors: KD
authors: Phelan
authors: J
authors: J
authors: Nakamura
authors: J P
authors: JP
authors: Gallagher
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002927:Cimetidine; D006146:Guanidines / Q000494:pharmacology; D006632:Histamine / Q000494:pharmacology*; D007093:Imidazoles / Q000494:pharmacology; D017446:Impromidine; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011968:Receptors, Histamine / Q000187:drug effects / Q000502:physiology*; D014725:Vestibular Nerve / Q000187:drug effects / Q000502:physiology*
chemical_list: D006146:Guanidines; D007093:Imidazoles; D011968:Receptors, Histamine; D002927:Cimetidine; D006632:Histamine; D017446:Impromidine