Ž.
B ain Resea ch 754 1997 298–302
Sho communica ion
E idence o wo ypes o nico inic ecep o s in he ca ca o id body
chemo ecep o cells
a´aab b
Ana Obeso , Ma ia Angeles Gomez-Nino , Lau a Alma az , B uce Dinge , Sal a o e Fidone ,
´˜
Cons ancio Gonzalez a,)
´
aDepa amen o de Bioquımica y Biologıa Molecula y Fisiologıa, Facul ad de Medicina, UniÕe sidad de Valladolid, 47005 Valladolid, Spain
´´ ´
b
Depa men o Physiology, UniÕe si y o U ah School o Medicine, Sal Lake Ci y, UT, USA
Accep ed 4 Feb ua y 1997
Abs ac
Cu en concep s on he loca ion and unc ional signi icance o nico inic ecep o s in he ca o id body es on
a
-bunga o oxin binding
and au o adiog aphic s udies. Using an in i o p epa a ion o he ca ca o id body whose ca echolamine deposi s ha e been labeled by
w
3
xw
3
x
p io incuba ion wi h he i ia ed na u al p ecu so H y osine, we ha e ound ha nico ine induces elease o H ca echolamines in a
Ž. Ž.
dose-dependen manne IC s9.81
m
M . We also ound ha mecamylamine 50
m
M comple ely abolished he nico ine-induced
50
Ž.
elease, while
a
-bunga o oxin 100 nM; 20 imes i s binding Konly educed he elease by 56%. These indings indica e ha
d
chemo ecep o cells, and pe haps o he ca o id body s uc u es, con ain nico inic ecep o s ha a e no sensi i e o
a
-bunga o oxin and
o ce a e ision o he cu en concep s on choline gic mechanisms in he ca o id body chemo ecep ion.
Keywo ds: Ca o id body; Nico inic ecep o ; Nico ine;
a
-Bunga o oxin; Ca echolamine
Ž.
The signi icance o ace ylcholine ACh in he ca o id
Ž.
body CB a e ial chemo ecep o s has been deba ed
h oughou he his o y o a e ial chemo ecep o s. Hey-
wx
mans e al. 17,18 disco e ed ha nico ine and exogenous
ACh, ac ing a he le el o he CB, can e oke espi a o y
e lexes compa able o hose p oduced by hypoxia and
wx
acidosis, and Schwei ze and W igh 24 obse ed ha
Ž.
p os igmine an inhibi o o ACh-es e ase mimicked he
ac ion o ACh. These indings lead o he p oposal ha
ACh would be he neu o ansmi e media ing he ac i a-
ion o he senso y ne e endings o he ca o id sinus ne e
Ž.
CSN . This p oposal, known as he choline gic hypo hesis
o CB chemo ecep ion, was highly deba ed, and in he
six ies Eyzagui e’s labo a o y accumula ed sound expe i-
men al e idence o suppo a nico inic ecep o -media ed
ole o ACh in he genesis o he ac i i y in he CSN, in
wx
esponse o a a ie y o s imuli 9 . Howe e , he con o-
e sy con inued because classical nico inic blocke s sup-
p essed he exci a o y ac ions o nico inic agonis s, bu
only educed in a a iable pe cen age he ac i a ion p o-
wx
duced by na u al s imuli 20,21 .
)Ž.
Co esponding au ho . Fax: q34 83 423588.
Biochemically, i was shown ha he CB con ains ACh
wx
12,16 , exp esses an adequa e ac i i y o choline ace yl
wx
ans e ase 16 , accumula es choline by a high a ini y
wx
sys em, and exhibi s a high u no e a e o ACh 10 . In
spi e o all hese da a, he ole o ACh in he chemo ecep-
ion p ocess emained elusi e. Radioligand binding and
w125 xŽ
au o adiog aphic s udies, using I
a
-bunga o oxin
a
-
.
BT as ligand in no mal, CSN-dene a ed and sympa hec-
omized CBs, showed ha he high a ini y speci ic bind-
ing was loca ed in chemo ecep o cells and sympa he ic
wx
endings, bu no in senso y ne e endings 4,5 . Elec o-
physiological s udies ha e also shown he p esence o
wx
nico inic ecep o s in chemo ecep o cells 15,25 , and
neu ochemically i has been shown ha chemo ecep o
Ž.
cells elease ca echolamines CA in esponse o nico inic
wx
agonis s 5,14 . These indings ha e been conside ed o
indica e ha ACh ac s as a seconda y neu o ansmi e
exclusi ely on he p esynap ic side o he chemo ecep o
wx
cell-senso y ne e ending synapse 11,13 .
The e is, howe e , a inding ha was no sa is ac o ily
explained: while classical nico inic blocke s ully elimi-
wx
na ed he nico ine-media ed exci a ion o he CSN 9,20 ,
a
-BT a a concen a ion nea 10 imes he K, inhibi ed by
d
only 50% he elease o CA and CSN discha ges elici ed
0006-8993 97 $17.00 Copy igh q1997 Else ie Science B.V. All igh s ese ed.
Ž.
PII S0006-8993 97 00185-6
()
A. Obeso e al. B ain Resea ch 754 1997 298–302 299
wx
by nico ine 5 . In he ligh o ecen ad ances in he
wx
biology o he nico inic ecep o 3,19,23 we ha e es ed
he possibili y ha chemo ecep o cells exp ess wo unc-
ional sub ypes o nico inic ecep o s, one sensi i e and
ano he insensi i e o
a
-BT. Using an in i o p epa a ion
Ž.
o ca CB whose ca echolamine CA deposi s ha e been
w3x
labeled by incuba ion wi h he na u al p ecu so H y o-
sine, we ha e ound ha
a
-BT, a concen a ions 20 imes
abo e i s binding K, inhibi s he nico ine e oked elease
d
w3x
o H CA by only 56%, while he classical nico ine
blocke mecamylamine a 50
m
M inhibi ed he nico ine-
e oked elease by 100%. These indings imply ha
chemo ecep o cells exp ess nico inic ecep o s con aining
wx
a
-
a
subuni s and he eby sensi i e o
a
-BT 19,23 , and
78
o he sub ypes o nico inic ecep o s wi h di e en
a
subuni s insensi i e o he oxin.
Expe imen s we e pe o med wi h CBs o adul ca s
Ž.
2.5–3.5 kg . The animals we e anes he ized wi h sodium
Ž.
pen oba bi al 40 mg kg; i.p. , and a e acheo omy, he
ca o id bi u ca ions we e iden i ied, emo ed and placed in
Ž
a luci e chambe con aining ice-cold modi ied Ty ode in
.
mM : NaCl, 112; KCl, 4.7; CaCl , 2.2; MgCl , 1.1;
22
.wx
sodium glu ama e, 42; HEPES, 5; glucose, 5.5 2 a pH
7.40 and equilib a ed wi h 100% O .
2
Unde a dissec ing mic oscope he CBs we e cleaned o
su ounding issue and he ea e incuba ed in glass ials
con aining 2 ml o Ty ode placed in a me abolic shake a
a cons an empe a u e o 378C. The incuba ing solu ion
Ž
con ained 100
m
M 6-me hyl- e ahyd op e ine a y osine
.Ž
hyd oxylase co ac o , 1 mM asco bic acid as a co ac o
.w3xŽ
o dopamine-
b
-hyd oxylase and 40
m
M H y osine 20
.
Ci mM; Ame sham , he na u al p ecu so o ca echol-
Ž.
amines CA . A e 2 h o incuba ion CA deposi s we e
labeled so ha each CB has syn hesized 12 pmol o
w3xŽ. 5
H dopamine DA , equi alen o 3=10 d.p.m., and
w3xŽ.
1 pmol o H no epineph ine NE , equi alen o 3
=104d.p.m. A e he labeling pe iod he o gans we e
ans e ed o new ials con aining 4 ml o p ecu so - ee
Ty ode con inuously bubbled wi h 100% O sa u a ed wi h
2
wa e apo . The solu ion was enewed e e y 30 min
du ing 2 h and disca ded; in his washing pe iod mos o
he p ecu so as well as he labile pool o labeled CA we e
w3x
los , and a e wa ds he basal elease o H CA was s able
wx
o se e al hou s 1 . The ea e he incuba ing solu ions
we e enewed e e y 10 min and collec ed o he ul e io
w3x
analysis in hei H CA con en .
The collec ion o incuba ing solu ions was g ouped in
s imula ion cycles, each cycle consis ing in a con ol sam-
ple o de e mine he basal elease, a s imulus sample
co esponding o he incuba ing pe iod in he p esence o
Ž.
he agen s es ed, and se e al pos -s imulus samples co -
esponding o pe iods o incuba ion wi h con ol solu ions
w3xŽ
un il he elease o H CA e u ned o he basal le el see
.Ž
Fig. 1A . Nico inic blocke s i.e., mecamylamine and
a
-
.Ž.
BT we e included in he con ol pe iod s p io o nico ine
applica ion o assu e an adequa e di usion o he d ug and
block o nico inic ecep o s. A gi en p epa a ion could be
subjec ed o one o mo e s imula ion cycles depending on
he e e sibili y o he e ec o he agen unde s udy. The
w3x
analysis o he eleased H CA included: acidi ica ion o
he collec ed incuba ing solu ions o pH 3.2 wi h a mix u e
o glacial ace ic and asco bic acid o a oid deg ada ion o
CA, bulk adso p ion o all ca echols eleased in o alumina
a a pH o 8.6, in ense washing o alumina columns wi h
dis illed wa e and bulk elu ion o all ca echols wi h 1 N
HCl. Pa o he elua e was used o de e mine he o al
w3x
amoun o H CA eleased in each pe iod by liquid
scin illa ion spec ome y, and he es was pooled wi h
co esponden samples o a o al o ou expe imen s, d ied
unde acuum, esuspended in he mobile phase con aining
unlabeled ca echols as ca ie s o he labeled subs ances,
and high pe o mance liquid ch oma og aphied o iden i y
w3x
Fig. 1. A: a s imula ion cycle o show he ime cou se o he elease o H ca echolamines induced by 100
m
M nico ine in he ca ca o id body. The line
Ž. Ž.
c ossing he his og am sepa a es g aphically he basal elease below om he e oked elease abo e . B: log dose- esponse cu e o nico ine on he
w3x
elease o H ca echolamine by he ca ca o id body. The elease esponse is exp essed as imes basal elease. Da a we e i ed o he ollowing unc ion:
wŽ.
p
x
ysAyA 1qx x , whe e A is he maximum e ec , x is he concen a ion o nico ine, x is he IC and pis he Hill coe icien . The IC
22 0 2 050 50
was 9.81
m
M. Da a a e means"S.E.M.; ns6.
()
A. Obeso e al. B ain Resea ch 754 1997 298–302300
w3xŽ
he ac ual H ca echol eleased o ch oma og aphic de-
wx.
ails see e . 14 . The e ec o a gi en agen on he
w3x
elease o H CA was calcula ed in wo di e en ways:
Ž.
i s , he e oked elease abo e he dashed line in Fig. 1A
was e e ed o he basal elease p io he applica ion o
he s imulus and exp essed as imes basal elease, and
second, he e oked elease by a gi en s imulus was e-
e ed o he issue con en and exp essed as pe cen o he
issue con en .
The signi icance o he e ec s obse ed was assessed
wi h a wo- ailed S uden - es o pai ed o unpai ed da a
acco ding o expe imen al design. [3]
E ec s o nico ine on he elease o H CA. Fig. 1A
shows a s imula ion cycle wi h 100
m
M nico ine. Nico-
w3x
ine-induced elease o H CA is ep esen ed by he d.p.m.
abo e he dashed line c ossing he his og am. No e ha
nea ly 80% o he e oked elease is collec ed du ing he 10
min pe iod co esponding o he nico ine applica ion, and
ha du ing he pos -s imulus pe iods he e is a slow de-
cline o he elease o each basal p e-s imula ion le els.
This slow phase o he e oked elease is ep esen ed by he
w3xw
3
x
washing-ou o H CA ca aboli es; a pa he H CA
eleased du ing he s imulus pe iod is aken ou by he
w3x
issues and deg aded, and he H ca aboli es a e slowly
disposed by he cells. Fig. 1B shows a dose-e ec cu e
w3x
o nico ine on he elease o H CA. The e oked elease
is exp essed as imes basal elease. A he lowes concen-
Ž.
a ion es ed 0.1
m
M , nico ine inc eased he elease o
w3x
H CA by a ac o o 0.65 abo e basal elease; maximal
esponse, co esponding o a elease o 14.4 imes abo e
basal was ob ained wi h 50
m
M nico ine, and he nico ine
Ž.
concen a ion p oducing hal maximal e ec IC was
50
9.81
m
M. The same IC was ob ained i he e oked
50
elease was exp essed as pe cen age o issue con en , he
w3x
Fig. 2. Analy ical p o ile o he H ca echol eleased. In basal condi ions
w3xŽ.
H dihyd oxyphenyl ace ic acid DOPAC , he main ca aboli e o
w3xw
3
x
H dopamine, ep esen ed 60% o he o al H ca echols eleased. Du -
w3x
ing hypoxic s imula ion H DOPAC amoun ed o 20% o he eleased
ma e ial and du ing nico inic s imula ion i ep esen ed 17%. The ca abo-
w3x
li es o H no epineph ine we e below de ec ion.
Fig. 3. E ec s o mecamylamine and
a
-bunga o oxin on he elease o
w3x
H ca echolamines elici ed by nico ine. The le g oup o columns
w3x
ep esen s he elease o H CA elici ed by 50
m
M nico ine du ing he
Ž. Ž .
s imulus S and he pos -s imulus PS pe iods. The middle g oup o
Ž.
columns shows he comple e inhibi ion o he nico ine 50
m
M elease
esponse p oduced by 50
m
M mecamylamine, and he igh g oup o
w3xŽ
columns co esponds o he elease o H CA p oduced by nico ine 50
.
m
M in he p esence o 100 nM
a
-bunga o oxin. Da a a e means"S.E.M.;
ns6 o nico ine and nico ine plus mecamylamine and ns8 o nico ine
plus
a
-bunga o oxin. )P-0.001 in all he cases.
basal elease in a 10 min pe iod ep esen ing 0.5% o he
issue con en .
w3x
Fig. 2 shows he analy ical p o ile o he H ca echols
ound in basal samples, in incuba ing samples co espond-
Ž.
ing o he s imula ion wi h nico ine 50
m
M , and o
compa a i e pu poses in incuba ing samples co esponding
Ž
o s imula ion wi h hypoxia incuba ion wi h 10% O -equi-
2
.w3xw
3
x
lib a ed solu ions . The a io o H DA H NE ound in
basal samples was 10.5, indica ing ha 91% o he o al
w3xw
3
x
H CA eleased was H DA and he emaining 9% was
w3x
H NE. These pe cen ages a e compa able o hose ound
wx
in he issues 22 , indica ing ha in basal condi ions bo h
w3x
H CA a e eleased a a a e p opo ional o hei issue
le els. Du ing hypoxic s imula ion he elease o bo h
w3xw
3
xw
3
x
H CA inc eased, and he H DA H NE a io in he
collec ed samples inc eased o 23, indica ing a p e e en ial
w3x
elease o H DA. On he con a y, du ing nico inic s imu-
w3xw
3
x
la ion he a io o H DA H NE in he collec ed sam-
ples d opped o a alue o 4, indica ing a p e e en ial
w3x
elease o H NE. E en a mo e ma ked p e e en ial e-
w3x
lease o H NE du ing nico inic s imula ion has been
wx
p e iously epo ed in he abbi CB 14 .
Fig. 3 shows he e ec o
a
-BT and mecamylamine on
w3x
he elease o H CA elici ed by nico ine. Since in p e i-
ous expe imen s i was ound ha maximal
a
-BT binding
Žwx.
was a ained in 30 min see e . 5 , he oxin was
included in he incuba ing solu ion o he h ee 10 min
con ol pe iods p io o and du ing nico ine applica ion;
()
A. Obeso e al. B ain Resea ch 754 1997 298–302 301
mecamylamine was included in he incuba ing solu ion o
a single 10 min con ol pe iod p io o and du ing nico ine
Ž.
applica ion. No e ha mecamylamine 50
m
M comple ely
blocked he elease induced by an iden ical concen a ion
o nico ine. Howe e ,
a
-BT a a concen a ion o 100 nM,
wx
which is nea ly 20 imes i s Kin binding expe imen s 5 ,
d
only inhibi ed he nico ine-induced elease by 56%. This
le el o inhibi ion is iden ical o ha ob ained wi h 50 nM
wx
a
-BT 5 , and he e o e i was no necessa y o es highe
concen a ions. Nei he nico inic blocke a ec ed he con-
w3x
ol uns imula ed o basal elease o H CA.
The main inding o his wo k is ha mecamylamine
w3x
comple ely inhibi s he elease o H CA while
a
-BT only
inhibi s 56%, indica ing ha he e is a se o nico inic
ecep o s in he CB ha is insensi i e o
a
-BT. These
esul s also imply ha he cu en concep s conce ning he
iden i ica ion and loca ion o nico inic ecep o s in he CB,
which a e based on
a
-BT binding and au o adiog aphic
expe imen s, need o be e ised.
w3x
The dose- esponse o nico ine on he elease o H CA
ob ained in he p esen s udy is displaced o he igh when
wx
compa ed o ha ob ained by Eyzagui e and Zapa a 7 o
ACh on he ca CSN discha ges. They epo ed a h eshold
Žy8.
o he esponse o 68 nM 10 g ml , an IC o
50
0.68
m
M and a maximal esponse a 6.8
m
M; hese
alues indica e a displacemen o he igh by mo e han an
o de o magni ude o he dose- esponse cu e epo ed
he e. A eady explana ion o his di e ence could be ha
ACh inc eases CSN discha ges ac ing on senso y ne e
endings and no on chemo ecep o cells; al e na i ely, he
CA eleased om chemo ecep o cells could ep esen he
d i e s o he CSN discha ges, in such a way ha small
inc eases in he elease abo e basal p oduce signi ican
inc eases in he CSN discha ges, and submaximal elease
Ž
p oduces maximal CSN ac ion po en ial equency see
.
below . I is impossible o compa e ou da a wi h hose
ob ained in o he s udies, because in mos o hem ACh o
nico ine we e adminis e ed in a-a e ially as bolus injec-
ions o in he in lowing ubing o he eco ding chambe .
w3x
The p e e en ial elease o H NE obse ed du ing nico-
inic s imula ion co ela es wi h he obse a ion ha nea ly
40% o he
a
-BT binding si es disappea a e ch onic CB
wx
sympa hec omy 5 and indica e ha a signi ican pa o
w3x
he H NE eleased comes om in aglomic sympa he ic
endings. In ac , and con a y o he si ua ion in he abbi
wx w
3x
14 , he p e e en ial elease o H NE obse ed unde
nico inic s imula ion in he ca CB disappea s a e sympa-
Ž.
hec omy Gomez-Nino, unpublished .
´˜
Ou indings wi h mecamylamine s.
a
-BT clea ly
demons a e ha pa o he nico inic ecep o s in he ca
CB a e no sensi i e o he snake oxin. Al hough he
p esen pha macological s udy does no allow o iden i y
he sub ypes o nico inic ecep o s, i is clea ha chemo e-
cep o cells should exp ess nico inic ecep o s wi h
a
o
7
a
subuni s, because only hese subuni s bind
a
-BT; i is
8
also clea ha hey mus exp ess nico inic ecep o s wi h
o he
a
subuni s, p obably o he sub ypes
a
o
a
35
which a e he mos commonly ound in sympa he ic neu-
wx
ons, and PC12 cells 19 which a e emb yologically e-
la ed o he CB. Ou indings in u n indica e ha p e ious
iden i ica ion o nico inic ecep o s on he basis o
a
-BT
binding and au o adiog aphic s udies ha e le ou pa o
he nico inic ecep o s in he CB, and he possibili y exis s
ha a pa o hese missed ecep o s a e loca ed in he
senso y ne e endings. The unambiguous answe o his
possibili y would equi e he demons a ion o he ecep-
o s in he senso y ne e endings and o he demons a-
ion o he message o hem in he chemo ecep o neu ons
o he pe osal ganglion by immunohis ochemical and o
in si u hyb idiza ion echniques. Howe e , he ac ha
nico inic e ec s on CSN discha ges a e g ea ly diminished
2q2qwx
o abolished in Ca - ee o Mg - ich solu ions 8,9
sugges s ha nico inic ecep o s a e p edominan ly o ex-
clusi ely loca ed in chemo ecep o cells, and he eby ha
nico inic e ec s on CSN discha ges a e media ed ia he
Ca2q-dependen elease o o he neu o ansmi e s. In con-
clusion, he p esen da a demons a ing ha a pa o he
nico inic ecep o s a e no sensi i e o
a
-BT obliga es a
e ision o he concep s o he choline gic mechanisms in
wx
he CB chemo ecep o s 6 .
Acknowledgemen s
Suppo ed by Spanish DGICYT G an PB92 0267 and
by NIH G an s NS07938 and NS12636.
Re e ences
wx
1 Alma az, L., Gonzalez, C. and Obeso, A., E ec s o high po assium
´
w3x
on he elease o H dopamine om he ca ca o id body in i o, J.
()Ž.
Physiol. Lond. , 379 1986 293–307.
wx
2 Ba on, M. and Eyzagui e, C., E ec s o empe a u e on some
memb ane cha ac e is ics o ca o id body cells, Am. J. Physiol., 233
Ž.
1977 C35–C46.
wx
3 Cla ke, P.B.S., The all and ise o neu onal alpha-bunga o oxin
Ž.
binding p o eins, T ends Pha macol. Sci., 13 1992 407–413.
wx
4 Dinge , B., Gonzalez, C., Yoshizaki, K. and Fidone, S., Alpha-
´
Ž.
bunga o oxin binding in ca ca o id body, B ain Res., 205 1981
187–193.
wx
5 Dinge , B., Gonzalez, C., Yoshizaki, K. and Fidone, S., Localiza ion
´
and unc ion o ca ca o id body nico inic ecep o s, B ain Res., 339
Ž.
1985 295–304.
wx
6 Eyzagui e, C., Fidone, S. and Nishi, K., Recen s udies on he
Ž.
gene a ion o chemo ecep o impulses. In: M.J. Pu es Ed. , The
Pe iphe al A e ial Chemo ecep o s, Camb idge Uni e si y P ess,
London, 1975, pp. 175–194.
wx
7 Eyzagui e, C. and Zapa a, P., The elease o ace ylcholine om
ca o id body issues. Fu he s udy on he e ec s o ace ylcholine
and choline gic blocking agen s on he chemosenso y discha ge, J.
()Ž.
Physiol. Lond. , 195 1968 589–607.
wx
8 Eyzagui e, C. and Zapa a, P., Pha macology o pH e ec s on
()
ca o id body chemo ecep o s in i o, J. Physiol. Lond. , 195
Ž.
1968 557–588.
wx
9 Eyzagui e, C. and Zapa a, P., A discussion o possible ansmi e
()
A. Obeso e al. B ain Resea ch 754 1997 298–302302
o gene a o subs ances in ca o id body chemo ecep o s. In: R.W.
Ž.
To ance Ed. , A e ial Chemo ecep o s, Blackwell Scien i ic Pub-
lica ions, Ox o d, 1968, pp. 213–251.
wx
10 Fidone, S., Wein aub, S., S a inoha, W., S i ling, C. and Jones, L.,
Endogenous ace ylcholine le els in ca ca o id body and he au o a-
diog aphic localiza ion o a high a ini y componen o choline
up ake. In: H. Acke , S. Fidone, D. Pallo , C. Eyzagui e, D.W.
Ž.
Lubbe s and R.W. To ance Eds. , Chemo ecep ion in he Ca o id
¨
Body, Sp inge -Ve lag, Be lin, 1977, pp. 106–113.
wx
11 Fidone, S.J. and Gonzalez, C., Ini ia ion and con ol o chemo ecep-
´
Ž.
o ac i i y in he ca o id body. In: A.P. Fishman Ed. , Handbook o
Physiology. The Respi a o y Sys em, Am. Physiol. Soc., Be hesda,
MD, 1986, pp. 247–312.
wx
12 Fidone, S.J., Wein aub, S.T. and S a inoha, W.B., Ace ylcholine
con en o no mal and dene a ed ca ca o id bodies measu ed by
py olysis gas ch oma og aphy mass agmen ome y, J. Neu-
Ž.
ochem., 26 1976 1047–1049.
wx
13 Gonzalez, C., Alma az, L., Obeso, A. and Rigual, R., Ca o id body
´
chemo ecep o s: om na u al s imuli o senso y discha ges, Physiol.
Ž.
ReÕ., 74 1994 .
wx
14 Gomez-Nino, A., Dinge , B., Ganzalez, C. and Fidone, S.J., Di e -
´˜ ´
en ial s imulus coupling o dopamine and no epineph ine s o es in
Ž.
abbi ca o id body ype I cells, B ain Res., 525 1990 160–164.
wx
15 Hayashida, Y. and Eyzagui e, C., Vol age noise o ca o id body
Ž.
ype I cells, B ain Res., 167 1979 189–194.
wx
16 Hells om, S., Pu a i e neu o ansmi e s in he ca o id body. Mass
agmen og aphic s udies, AdÕ. Biochem. Psychopha macol.,16
Ž.
1977 257–263.
wx
17 Heymans, C., Bouckae , J.J. and Dau ebande, L., Sinus ca o idien
e e lexes espi a oi es; sensibili e des sinus ca o idiens aux sub-
´´
s ances chimiques. Ac ion s imulan e espi a oi e e lexe du sul u e
´
de sodium, du cyanu e de po assium, de la nico ine e de la lobeline,
´
Ž.
A ch. In . Pha macodyn. The ., 40 1931 54–91.
wx
18 Heymans, C., Bouckae , J.J., Fa be , S. and Hsu, F.J., In luence
e lexogene de l’ace ylcholine su les e minaisons ne euses
´` ´
chimio-sensi i es du sinus ca o idien, A ch. In . Pha macodyn.
Ž.
The ., 54 1936 129–135.
wx
19 McGehee, D.S. and Role, L.W., Physiological di e si y o nico inic
ace ylcholine ecep o s exp essed by e eb a e neu ons, Annu. ReÕ.
Ž.
Physiol., 57 1995 521–546.
wx
20 McQueen, D.S., A quan i a i e s udy o he e ec s o choline gic
()
d ugs on ca o id chemo ecep o s in he ca , J. Physiol. Lond. , 273
Ž.
1977 515–532.
wx
21 McQueen, D.S., Pha macological aspec s o pu a i e ansmi e s in
Ž.
he ca o id body. In: H. Acke and R.G. O’Regan Eds. , Physiology
o he Pe iphe al A e ial Chemo ecep o s, Else ie Science, Ams-
e dam, 1983, pp. 149–195.
wx
22 Rigual, R., Gonzalez, E., Gonzalez, C., Jones, L. and Fidone, S., A
´´
compa a i e s udy o he me abolism o ca echolamines in he abbi
Ž.
and ca ca o id body. In: J.A. Ribei o and D.J. Pallo Eds. ,
Chemo ecep o s in Respi a o y Con ol, C oom Helm, London,
1987, pp. 124–134.
wx
23 Sa gen , P.B., The di e si y o neu onal nico inic ace ylcholine
Ž.
ecep o s, Annu. ReÕ. Neu osci., 16 1993 403–443.
wx
24 Schwei ze , A. and W igh , S., Ac ion o p os igmine and ace yl-
Ž.
choline on espi a ion, Qua . J. Exp. Physiol., 28 1938 33–47.
wx
25 Wya , C.N. and Pee s, C., Nico inic ace ylcholine ecep o s in
isola ed ype I cells o he neona al a ca o id body, Neu oscience,
Ž.
54 1993 275–281.