Pd. Marley et al., NERVES CONTAINING NITRIC-OXIDE SYNTHASE AND THEIR POSSIBLE FUNCTION IN THE CONTROL OF CATECHOLAMINE SECRETION IN THE BOVINE ADRENAL-MEDULLA, Journal of the autonomic nervous system, 54(3), 1995, pp. 184-194
NADPH-diaphorase reactivity and neuronal nitric oxide synthase (nNOS)
immunostaining have been localised in sections of bovine adrenal gland
s. Both were present in nerve fibres and terminals in the subcapsular
region and running between zona glomerulosa cells, amongst the medulla
ry chromaffin cells, between large ganglion cells in rare encapsulated
medullary ganglia and in large nerve bundles running through the cort
ex. Occasional isolated fibres were stained in deeper cortical layers.
Both NADPH-diaphorase reactivity and nNOS immunoreactivity were prese
nt in a population of ganglion cells located individually or in small
groups at the medullary-cortical boundary. NADPH-diaphorase reactivity
was also found in all cortical cells (zona glomerulosa cells being mo
re densely stained than other cortical cells) and in large fibrous str
uctures in large nerve bundles (tentatively identified as glial cells)
: these structures were not stained with antisera to nNOS. Chromaffin
cells were not stained with either technique. The possible role of neu
rally-released nitric oxide in the regulation of nerve-induced catecho
lamine secretion from chromaffin cells was investigated in isolated, p
erfused, bovine adrenal glands. The secretion of both adrenaline and n
oradrenaline in response to field stimulation of adrenal nerves at eit
her 2 Hz or 10 Hz was unaffected by the presence of N-omega-nitro-L-ar
ginine (30 mu M), sodium nitroprusside (10 mu M) or L-arginine (100 mu
M) in the perfusing solution. It is concluded that, although nitric o
xide may be generated and released from adrenal medullary nerves inner
vating chromaffin cells, it does not play a direct role in the acute r
egulation of adrenal catecholamine secretion.