LONG-TERM HYPOXIA INCREASES THE NUMBER OF NOREPINEPHRINE-CONTAINING GLOMUS CELLS IN THE RAT CAROTID-BODY - A CORRELATIVE IMMUNOCYTOCHEMICALAND BIOCHEMICAL-STUDY
A. Verna et al., LONG-TERM HYPOXIA INCREASES THE NUMBER OF NOREPINEPHRINE-CONTAINING GLOMUS CELLS IN THE RAT CAROTID-BODY - A CORRELATIVE IMMUNOCYTOCHEMICALAND BIOCHEMICAL-STUDY, Journal of the autonomic nervous system, 44(2-3), 1993, pp. 171-177
A group of adult rats was divided into two subgroups: one was submitte
d to long-term normobaric hypoxia (10% O2, two weeks) while the other
(control group) was kept in the same room, breathing air. Animals from
each subgroup were used to study either the norepinephrine content of
the carotid body by high pressure liquid chromatography or to localiz
e norepinephrine-containing structures using an immunocytochemical pro
cedure (peroxidase-labelled antibodies on cryostat sections). The bioc
hemical study showed, as expected, a large increase in carotid body no
repinephrine content (19-fold) and turnover (ten-fold) in hypoxic rats
. The immunocytochemical study revealed only a few norepinephrine-immu
nopositive glomus cells in sections through the carotid body of normox
ic rats, whereas the carotid body of hypoxic rats showed a very large
number of norepinephrine-positive glomus cells. This increase was quan
tified, using an image analyser, and it was found to constitute a 61-f
old increase in the number of immunopositive profiles per section and
a 29-fold increase in the immunopositive profile area/section area rat
io. It is concluded that long-term hypoxia increases rat carotid body
norepinephrine content by inducing norepinephrine synthesis in glomus
cells in which this amine was not detectable previously, before hypoxi
a.