Developmental changes in the expression of Shaker- and Shab-related K(+) channels in neurons of the rat trigeminal ganglion.
We have investigated properties of voltage-gated K(+) channels in neurons of the pre- and postnatal rat trigeminal ganglion (TG). To correlate functional data with information on gene expression of Shaker- and Shab-related channels in these pseudo-unipolar neurons, the patch-clamp technique was combined with the single-cell reverse transcription-polymerase chain reaction (RT-PCR). A majority (80%) of prenatal TG neurons possessed only sustained delayed rectifier currents with half-maximal current inactivation at -30 mV. In the postnatal cells, steady-state inactivation of sustained currents occurred at more negative voltages (half-maximal inactivation at -58 mV). About 65% of the postnatal cells displayed a transient outward component in addition to the sustained currents. With increasing age, the sensitivity of sustained currents to 4-aminopyridine (4-AP) decreased significantly. The Shaker channel toxins, alpha-dendrotoxin and agitoxin-2 (50 and 10 nM), were much less effective. Discrimination between both stages with tetraethylammonium chloride (5 mM) was not possible since the currents were reduced generally by about 50%. After recording, the cell content was harvested and single-cell RT-PCR was performed to compare K(+) current properties and mRNA expression within the same cell. Most cells simultaneously expressed several different Shaker- and Shab-like transcripts. At postnatal day 14, the frequency of cells carrying transcripts encoding Kv1.1 decreased. Detailed analysis revealed a higher 4-AP sensitivity of TG neurons expressing Kv1.1 transcripts.
Seifert
G
G
Experimental Neurobiology, Neurosurgery, University of Bonn, Sigmund-Freud-Str. 25, 53105, Bonn, Germany. gese@mailer.meb.uni-bonn.de
Kuprijanova
E
E
Zhou
M
M
Steinhäuser
C
C
D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D019256:Cadmium Chloride / Q000494:pharmacology; D051668:Delayed Rectifier Potassium Channels; D004546:Elapid Venoms / Q000494:pharmacology; D004622:Embryo, Mammalian / Q000166:cytology / Q000502:physiology; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000235:genetics*; D024642:Potassium Channels, Voltage-Gated; D011247:Pregnancy; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012604:Scorpion Venoms / Q000494:pharmacology; D051669:Shab Potassium Channels; D051637:Shaker Superfamily of Potassium Channels; D019789:Tetraethylammonium / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D012668:Trigeminal Ganglion / Q000166:cytology / Q000196:embryology / Q000378:metabolism*
D051668:Delayed Rectifier Potassium Channels; D004546:Elapid Venoms; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D012333:RNA, Messenger; D012604:Scorpion Venoms; D051669:Shab Potassium Channels; D051637:Shaker Superfamily of Potassium Channels; C087603:agitoxin 2; D013779:Tetrodotoxin; D019789:Tetraethylammonium; C020273:dendrotoxin; D015761:4-Aminopyridine; D019256:Cadmium Chloride