Experiments were performed on adult rainbow trout (Oncorhynchus mykiss) in vivo using chronically cannulated fish and in situ using a perfused posterior cardinal vein preparation (i) to characterise the desensitisation of chromaffin cell nicotinic receptors and (ii) to assess the ability of fish to secrete catecholamines during acute hypoxia with or without functional nicotinic receptors. Intra-arterial injection of nicotine (6.0×10(−)(7)mol kg(−)(1)) caused a rapid increase in plasma adrenaline and noradrenaline levels; the magnitude of this response was unaffected by an injection of nicotine given 60 min earlier. Evidence for nicotinic receptor desensitisation, however, was provided during continuous intravenous infusion of nicotine (1.3×10(−)(5)mol kg(−)(1)h(−)(1)) in which plasma catecholamine levels increased initially but then returned to baseline levels. To ensure that the decline in circulating catecholamine concentrations during continuous nicotine infusion was not related to changes in storage levels or altered rates of degradation/clearance, in situ posterior cardinal vein preparations were derived from fish previously experiencing 60 min of saline or nicotine infusion. Confirmation of nicotinic receptor desensitisation was provided by demonstrating that the preparations derived from nicotine-infused fish were unresponsive to nicotine (10(−)(5)mol l(−)(1)), yet remained responsive to angiotensin II (500 pmol kg(−)(1)). The in situ experiments demonstrated that desensitisation of the nicotinic receptor occurred within 5 min of receptor stimulation and that resensitisation was established 40 min later. The ability to elevate plasma catecholamine levels during acute hypoxia (40–45 mmHg; 5.3-6.0 kPa) was not impaired in fish experiencing nicotinic receptor desensitisation. Indeed, peak plasma adrenaline levels were significantly higher in the desensitised fish during hypoxia than in controls (263+/−86 versus 69+/−26 nmol l(−)(1); means +/− s.e.m., N=6-9). Thus, the results of the present study demonstrate that activation of preganglionic sympathetic cholinergic nerve fibres and the resultant stimulation of nicotinic receptors is not the sole mechanism for eliciting catecholamine secretion during hypoxia.

Bernier
N. J.
,
Perry
S. F.
(
1997
).
Angiotensins stimulate catecholamine release from the chromaffin tissue of the rainbow trout
.
Am. J. Physiol
273
,
49
–.
Bernier
N. J.
,
Perry
S. F.
(
1999
).
Cardiovascular effects of angiotensin-II-mediated adrenaline release in rainbow trout Oncorhynchus mykiss
.
J. Exp. Biol
202
,
55
–.
Boksa
P.
,
Livett
B. G.
(
1984
).
Desensitisation to nicotinic cholinergic agonists and K+, agents that stimulate catecholamine secretion, in isolated adrenal chromaffin cells
.
J. Neurochem
42
,
607
–.
Borgese
F.
,
Sardet
C.
,
Cappadoro
M.
,
Pouyssegur
J.
,
Motais
R.
(
1992
).
Cloning and expression of a cAMP-activated Na+/H+exchanger — evidence that the cytoplasmic domain mediates hormonal regulation
.
Proc. Natl. Acad. Sci. USA
89
,
6765
–.
Burgoyne
R. D.
,
Morgan
A.
,
Robinson
I.
,
Pender
N.
,
Cheek
T.
(
1993
).
Exocytosis in adrenal chromaffin cells
.
J. Anat
183
,
309
–.
Epple
A.
,
Navarro
I.
,
Horak
P.
,
Spector
S.
(
1993
).
Endogenous morphine and codeine: release by the chromaffin cells of the eel
.
Life Sci
52
,
117
–.
Epple
A.
,
Nibbio
B.
,
Spector
S.
,
Brinn
J. E.
(
1994
).
Endogenous codeine — autocrine regulator of catecholamine release from chromaffin cells
.
Life Sci
54
,
695
–.
Fritsche
R.
,
Reid
S. G.
,
Thomas
S.
,
Perry
S. F.
(
1993
).
Serotonin-mediated release of catecholamines in the rainbow trout Oncorhynchus mykiss
.
J. Exp. Biol
178
,
191
–.
Furimsky
M.
,
Moon
T. W.
,
Perry
S. F.
(
1996
).
Calcium signalling in isolated single chromaffin cells of the rainbow trout (Oncorhynchus mykiss)
.
J. Comp. Physiol
166
,
396
–.
Gfell
B.
,
Kloas
W.
,
Hanke
W.
(
1997
).
Neuroendocrine effects of adrenal hormone secretion in carp (Cyprinus carpio)
.
Gen. Comp. Endocr
106
,
310
–.
Julio
A. E.
,
Montpetit
C.
,
Perry
S. F.
(
1998
).
Does blood acid—base status modulate catecholamine secretion in the rainbow trout (Oncorhynchus mykiss)?
.
J. Exp. Biol
201
,
3085
–.
Liu
P. S.
,
Kao
L. S.
(
1990
).
Na+-dependent Ca2+influx in bovine adrenal chromaffin cells
.
Cell Calcium
11
,
573
–.
Livett
B. G.
,
Marley
P. D.
(
1993
).
Noncholinergic control of adrenal catecholamine secretion
.
J. Anat
183
,
277
–.
Malhotra
R. K.
,
Wakade
T. D.
,
Wakade
A. R.
(
1988
).
Comparison of secretion of catecholamines from the rat adrenal medulla during continuous exposure to nicotine, muscarine or excess K
.
Neuroscience
26
,
313
–.
Marley
P. D.
(
1988
).
Desensitization of the nicotinic secretory response of adrenal chromaffin cells
.
Trends Pharmac. Sci
9
,
102
–.
Montpetit
C. J.
,
Perry
S. F.
(
1999
).
Neuronal cholinergic control of catecholamine secretion from chromaffin cells in the rainbow trout (Oncorhynchus mykiss)
.
J. Exp. Biol
202
,
2059
–.
Motais
R.
,
Borgese
F.
,
Fievet
B.
,
Garcia-Romeu
F.
(
1992
).
Regulation of Na+/H+exchange and pH in erythrocytes of fish
.
Comp. Biochem. Physiol
102
,
597
–.
Nandi
J.
(
1961
).
New arrangement of interrenal and chromaffin tissues in teleost fish
.
Science
134
,
389
–.
Nilsson
S.
,
Abrahamson
T.
,
Grove
D. J.
(
1976
).
Sympathetic nervous control of adrenaline release from the head kidney of the cod, Gadus morhua
.
Comp. Biochem. Physiol
55
,
123
–.
Nilsson
S.
,
Grove
D. J.
(
1974
).
Adrenergic and cholinergic innervation of the spleen of the cod, Gadus morhua
.
Eur. J. Pharmac
28
,
135
–.
Ochoa
E. L. M.
,
Chattopadhyay
A.
,
McNamee
M. G.
(
1989
).
Desensitization of the nicotinic acetylcholine receptor: Molecular mechanisms and effects of modulators
.
Cell. Mol. Neurobiol
9
,
141
–.
Perry
S. F.
,
Daxboeck
C.
,
Dobson
G. P.
(
1985
).
The effect of perfusion flow rate and adrenergic stimulation on oxygen transfer in the isolated, saline-perfused head of rainbow trout (Salmo gairdneri)
.
J. Exp. Biol
116
,
251
–.
Perry
S. F.
,
Fritsche
R.
,
Kinkead
R.
,
Nilsson
S.
(
1991
).
Control of catecholamine release in vivo and in situ in the Atlanticcod (Gadus morhua) during hypoxia
.
J. Exp. Biol
155
,
549
–.
Perry
S. F.
,
Gilmour
K. M.
(
1996
).
Consequences of catecholamine release on ventilation and blood oxygen transport during hypoxia and hypercapnia in an elasmobranch (Squalus acanthias) and a teleost (Oncorhynchus mykiss)
.
J. Exp. Biol
199
,
2105
–.
Perry
S. F.
,
Kinkead
R.
(
1989
).
The role of catecholamines in regulating arterial oxygen content during hypercapnic acidosisin rainbow trout (Salmo gairdneri)
.
Respir. Physiol
77
,
365
–.
Perry
S. F.
,
Reid
S. D.
(
1992
).
Relationships between bloodoxygen content and catecholamine levels during hypoxia inrainbow trout and American eel
.
Am. J. Physiol
263
,
240
–.
Primmett
D. R. N.
,
Randall
D. J.
,
Mazeaud
M.
,
Boutilier
R. G.
(
1986
).
The role of catecholamines in erythrocyte pH regulation an oxygen transport in rainbow trout (Salmo gairdneri) during exercise
.
J. Exp. Biol
122
,
139
–.
Reid
S. G.
,
Bernier
N.
,
Perry
S. F.
(
1998
).
The adrenergic stress response in fish: control of catecholamine storage and release
.
Comp. Biochem. Physiol
120
,
1
–.
Reid
S. G.
,
Fritsche
R.
,
Jonsson
A. C.
(
1995
).
Immunohistochemical localization of bioactive peptides and amines associated with the chromaffin tissue of five species of fish
.
Cell Tissue Res
280
,
499
–.
Ristori
M. T.
,
Laurent
P.
(
1989
).
Plasma catecholamines in rainbow trout (Salmo gairdneri) during hypoxia
.
J. Exp. Biol
48
,
285
–.
Ritthaler
T.
,
Schricker
K.
,
Kees
F.
,
Kramer
B.
,
Kurtz
A.
(
1997
).
Acute hypoxia stimulates renin secretion and renin gene expression in vivo but not in vitro
.
Am. J. Physiol
41
,
1105
–.
Rowell
P. P.
,
Duggan
D. S.
(
1998
).
Long-lasting inactivation of nicotinic receptor function in vitro by treatment with high concentrations of nicotine
.
Neuropharmac
37
,
103
–.
Schwartz
R. D.
,
Kellar
K. J.
(
1983
).
Nicotinic cholinergic receptor binding sites in the brain: regulation in vivo
.
Science
220
,
214
–.
Soivio
A.
,
Nynolm
K.
,
Westman
K.
(
1975
).
A technique forrepeated sampling of the blood of individual resting fish
.
J. Exp. Biol
62
,
207
–.
Thomas
S.
,
Kinkead
R.
,
Wood
C. M.
,
Walsh
P. J.
,
Perry
S. F.
(
1991
).
Desensitisation of adrenaline-induced red blood cell H+extrusion in vitro after chronic exposure of rainbow trout (Salmo gairdneri) to moderate environmental hypoxia
.
J. Exp. Biol
156
,
233
–.
Thomas
S.
,
Perry
S. F.
(
1992
).
Control and consequences ofadrenergic activation of red blood cell Na+/H+exchange on blood oxygen and carbon dioxide transport
.
J. Exp. Zool
263
,
160
–.
Wada
A.
,
Takara
H.
,
Izumi
F.
,
Kobayashi
H.
,
Yanagihara
N.
(
1985
).
Influx of 22Na through receptor-associated Na channels: relationship between 22Na influx, 45Ca influx and secretion of catecholamines in cultured bovine adrenal medulla cells
.
Neuroscience
15
,
283
–.
Watanabe
T.
,
Shimamoto
N.
,
Takahashi
A.
,
Fujino
M.
(
1995
).
PACAP stimulates catecholamine release from the adrenal medulla: a novel noncholinergic secretagogue
.
Am. J. Physiol
269
,
903
–.
Yamaguchi
N.
(
1993
).
In vivo evidence for adrenal catecholamine release mediated by non-nicotinic mechanisms: local medullary effect of VIP
.
Am. J. Physiol
265
,
766
–.
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