Kv4 (A-type) potassium currents in the mouse medial nucleus of the trapezoid body.
Principal neurones of the mouse medial nucleus of the trapezoid body (MNTB) possess multiple voltage-gated potassium currents, including a transient outward current (or A-current), which is characterized here. The A-current exhibited rapid voltage-dependent inactivation and was half inactivated at resting membrane potentials. Following a hyperpolarizing pre-pulse to remove inactivation, the peak transient current was 1.07 nA at -17 mV. The pharmacological characteristics of this A-current were consistent with Kv4 subunits in expression studies; the A-current was resistant to block by tetraethylammonium and dendrotoxin-I but sensitive to millimolar concentrations of 4-aminopyridine and 5 microM hanatoxin. Immunohistochemistry confirmed that Kv4.3 sub-units are present in the MNTB. In a single-compartment model of an MNTB neurone, the A-current served to accelerate the decay of the initial action potentials in a stimulus train and suggested that removal of A-current steady-state inactivation could raise firing threshold for non-calyceal synaptic inputs. This A-type current was not observed in the rat.
Johnston
Jamie
J
MRC Toxicology Unit and Department of Cell Physiology and Pharmacology, University of Leicester, Leicester LE1 9HN, UK.
Griffin
Sarah J
SJ
Baker
Claire
C
Forsythe
Ian D
ID
D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D001306:Auditory Pathways / Q000166:cytology / Q000502:physiology; D001933:Brain Stem / Q000166:cytology / Q000502:physiology*; D051379:Mice; D008808:Mice, Inbred CBA; D009474:Neurons / Q000502:physiology; D009924:Organ Culture Techniques; D021122:Protein Subunits / Q000502:physiology*; D051381:Rats; D051672:Shal Potassium Channels / Q000502:physiology*; D013045:Species Specificity
D021122:Protein Subunits; D051672:Shal Potassium Channels