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Heat-activated currents in neurons cultured from rat dorsal root ganglia
s195
385 TOMOYA
HEAT-ACTIVATED
CURRENTS
CULTURED
RAT DORSAL ROOT GANGLIA
TERAUCHI,
KEIZO TAKAO,
Dept. of Bioinformatics, Nociceptive However.
FROM
heat-activated
voltage-clamp
AIKO HORI, KIYOSHI MATSUMURA,
Graduate School of Informatics, non-selective
non-nociceptive
heat-activated
IN NEURONS
Kyoto Univ.. Sakyo-ku,
cation current has been reported
heat-activated
current
(-60 mV)
recording
warming
above
a threshold
Kyoto 606-8501
in neurons of rat dorsal root wglia
has not been clarified.
current in neurons cultured from DRG of l-2 weeks-old
SHIGEO KOBAYASHI
Here. we investigated
rats by patch-clamp
temperature
induced
whole-cell inward
(DRG).
ionic mechanism recording.
current.
of In
Threshold
temperature distributed widely from 30 to 45 oC. The heat-activated current was not inhibited by extracellular application of ruthenium red. indicating that the conductance was different from that of capsaicin receptors. GDPpS added in pipette mediated
solution
did not block the heat-activated
by G-protein.
Moreover,
EGTA
suggesting that it was not modulated activated conductance
386
current.
added in pipette
by intracellular
suggesting
solution
free Ca ions.
activation
was not
did not change the heat-activated
that the current
current,
We clarified properties
of non-nociceptive
heat-
in a subset of DRG neurons.
WARM CELLS IN CULTURED
REVEALED BY MICROFLUORIMETRY OF Ca2+ DORSAL ROOT GANGLION NEURONS
H. Gotoh, H. Akatsuka, K. Suto Dept. of Bioengineering,
Fat. of Engineering, Soka University,
Tangicho l-236, Hachioji, Tokyo 192
Warm cells were identified by Fura-PE3-based microfluorimetry of Ca2+ in cultured dorsal root ganglion (DRG) neurons. In response to a physiologically relevant stimulus temperature (43”C), a subpopulation of small DRG neurons from new born rats increased the intracellular Ca2+ concentration ([Ca2+]i). 7% (18 cells out of 254 cells checked in total) of the cells responded to the warm stimulus. The residual cells showed very weak response; we ignored these nonspecific responders . The stimulus evoked elevation in [Ca2+]i from 52.5 z 9.5 nM (Mean i SD, n=18) to 171.0 + 15.6 nM in cells between 15 and 25 Q m in diameter. The Ca2+ response was reproducible and the same single cell body produced a smilar degree of [ Ca2+]i increase at least 5 times at the interval of 3 min. The depletion of extracellular Ca2+ diminished the Ca2+ elevation. The Na+-free condition also diminished the response. We concluded that the heat stimulation opens nonselective cation channels in putative warm cells from DRG neurons. ( Gotoh H. et al.. Brain Res., 796,319-322, 1998)
387
CHARACJEUZATION OF COLD CELLS
KIMIHIKO
SL’O.
Fat. ol Englnecrlng,
Soda I.niv..
of coid stimulus transduction
NEL’RONS
Fura-PW
(5!t\1)-loaded
marked Increase 111[Ca’-1,. 17% of the neurons \I cre response\-e neurons
larger In small-d~amertr The absence
I 15-Xbtm).
of cvtracellular
Ca”
’ c;, kKh!OJI. l--3.
Tangxho
192-8577
Tokyo
\\ a< 1111 estlgatcd m 1 ~tro b! us1n9 cultured dorsal root panghon (DRG)
neurons l‘rom nex born rats. In the Ca” Indlator
temperature.
DORSAL ROOT GANGLION
IHIDEKI GOTOH
Dept. or Blocnglncennp.
The mechamsm
IN CULTURED
More &Is
and the magnrludc
exhIbIted
ncarl> nulhllcd
neurol~s a1 35 (‘ , coohng
01. the mcrcase \\ a5 slgmficantl!
the cold response
the lesponsc.
10 25 c caused
depending
\\ hlle Sa+-free
detectable effect. In cold cells. tn o classes ha\ e been Identitled m respect of the 5pxlflclt>
lo
on the stimulus
condltlon
on@ to the cold stlmulntlon !around 25 <’). and the other ha!, a polb modal ntx~ccpt~on (se\ ercr coldness). scnsItI\ It!- ret ealed that
1112
latter \\ ~15a pal\ modal noclceptor.
These data suggest that the cold stnnulatlon opens Ca’--permeable
sholred
no
cold Furnull. One responds
channels In cold cell\ from DRG neuron\.
Bradykuun
385 TOMOYA
HEAT-ACTIVATED
CURRENTS
CULTURED
RAT DORSAL ROOT GANGLIA
TERAUCHI,
KEIZO TAKAO,
Dept. of Bioinformatics, Nociceptive However.
FROM
heat-activated
voltage-clamp
AIKO HORI, KIYOSHI MATSUMURA,
Graduate School of Informatics, non-selective
non-nociceptive
heat-activated
IN NEURONS
Kyoto Univ.. Sakyo-ku,
cation current has been reported
heat-activated
current
(-60 mV)
recording
warming
above
a threshold
Kyoto 606-8501
in neurons of rat dorsal root wglia
has not been clarified.
current in neurons cultured from DRG of l-2 weeks-old
SHIGEO KOBAYASHI
Here. we investigated
rats by patch-clamp
temperature
induced
whole-cell inward
(DRG).
ionic mechanism recording.
current.
of In
Threshold
temperature distributed widely from 30 to 45 oC. The heat-activated current was not inhibited by extracellular application of ruthenium red. indicating that the conductance was different from that of capsaicin receptors. GDPpS added in pipette mediated
solution
did not block the heat-activated
by G-protein.
Moreover,
EGTA
suggesting that it was not modulated activated conductance
386
current.
added in pipette
by intracellular
suggesting
solution
free Ca ions.
activation
was not
did not change the heat-activated
that the current
current,
We clarified properties
of non-nociceptive
heat-
in a subset of DRG neurons.
WARM CELLS IN CULTURED
REVEALED BY MICROFLUORIMETRY OF Ca2+ DORSAL ROOT GANGLION NEURONS
H. Gotoh, H. Akatsuka, K. Suto Dept. of Bioengineering,
Fat. of Engineering, Soka University,
Tangicho l-236, Hachioji, Tokyo 192
Warm cells were identified by Fura-PE3-based microfluorimetry of Ca2+ in cultured dorsal root ganglion (DRG) neurons. In response to a physiologically relevant stimulus temperature (43”C), a subpopulation of small DRG neurons from new born rats increased the intracellular Ca2+ concentration ([Ca2+]i). 7% (18 cells out of 254 cells checked in total) of the cells responded to the warm stimulus. The residual cells showed very weak response; we ignored these nonspecific responders . The stimulus evoked elevation in [Ca2+]i from 52.5 z 9.5 nM (Mean i SD, n=18) to 171.0 + 15.6 nM in cells between 15 and 25 Q m in diameter. The Ca2+ response was reproducible and the same single cell body produced a smilar degree of [ Ca2+]i increase at least 5 times at the interval of 3 min. The depletion of extracellular Ca2+ diminished the Ca2+ elevation. The Na+-free condition also diminished the response. We concluded that the heat stimulation opens nonselective cation channels in putative warm cells from DRG neurons. ( Gotoh H. et al.. Brain Res., 796,319-322, 1998)
387
CHARACJEUZATION OF COLD CELLS
KIMIHIKO
SL’O.
Fat. ol Englnecrlng,
Soda I.niv..
of coid stimulus transduction
NEL’RONS
Fura-PW
(5!t\1)-loaded
marked Increase 111[Ca’-1,. 17% of the neurons \I cre response\-e neurons
larger In small-d~amertr The absence
I 15-Xbtm).
of cvtracellular
Ca”
’ c;, kKh!OJI. l--3.
Tangxho
192-8577
Tokyo
\\ a< 1111 estlgatcd m 1 ~tro b! us1n9 cultured dorsal root panghon (DRG)
neurons l‘rom nex born rats. In the Ca” Indlator
temperature.
DORSAL ROOT GANGLION
IHIDEKI GOTOH
Dept. or Blocnglncennp.
The mechamsm
IN CULTURED
More &Is
and the magnrludc
exhIbIted
ncarl> nulhllcd
neurol~s a1 35 (‘ , coohng
01. the mcrcase \\ a5 slgmficantl!
the cold response
the lesponsc.
10 25 c caused
depending
\\ hlle Sa+-free
detectable effect. In cold cells. tn o classes ha\ e been Identitled m respect of the 5pxlflclt>
lo
on the stimulus
condltlon
on@ to the cold stlmulntlon !around 25 <’). and the other ha!, a polb modal ntx~ccpt~on (se\ ercr coldness). scnsItI\ It!- ret ealed that
1112
latter \\ ~15a pal\ modal noclceptor.
These data suggest that the cold stnnulatlon opens Ca’--permeable
sholred
no
cold Furnull. One responds
channels In cold cell\ from DRG neuron\.
Bradykuun