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| TR |
TITLE |
AUTHORS |
KEYWORDS |
MATERIALS & METHODS
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MICROSCOPIC
TECHNIQUES |
SPECIES |
MORPHOLOGY |
CELL
LINE |
| 587 |
Subunit
composition and role of Na+,K+-ATPases in adrenal chromaffin cells |
Hai
Lin, Shoichiro Ozaki, Naoji Fujishiro, Kazuo Takeda, Issei Imanaga, Glenn D Prestwich, and Masumi
Inoue |
cortical
hormones, amperometry, ouabain |
After incubation, tissues were
washed in Ca2+-deficient solution, and placed in a dish with non-fluorescent glass at the central
area (MatTek), then dissociated using fine needles.
|
laser
confocal microscopy |
guinea-pig |
|
AM |
| Abstract |
| |
Adrenal medullary (AM) cells are exposed to high concentrations
of cortical hormones, one of which is a ouabain-like substance. Thus, the effects of ouabain
on catecholamine secretion and distribution of Na+,K+-ATPase a and ß subunits in rat and
guinea-pig AM cells were examined using amperometry and immunological techniques. While exposure
to 1 µm ouabain did not have a marked effect on resting secretion, it induced an increase
in secretion due to mobilization of Ca2+ ions that were stored during a 4 min interval between
muscarine applications. Immunocytochemistry revealed that Na+,K+-ATPase a1 subunit-like and
ß3 subunit-like immunoreactive (IR) materials were distributed ubiquitously at the cell
periphery, whereas a2- and ß2-like IR materials were present in restricted parts of the
cell periphery. The a1 and a2 subunits were mainly immunoprecipitated from AM preparations by
anti-ß3 and anti-ß2 antisera, respectively. Peripheral BODIPY-FL-InsP3 binding sites
were localized below membrane domains with a2- and ß2-like IR materials. The results indicate
that in AM cells, a1ß3 isozymes of Na+,K+-ATPase were present ubiquitously in the plasma
membrane, while a2ß2 isozymes were in the membrane domain closely associated with peripheral
Ca2+ store sites. This close association of the a2ß2 isozyme with peripheral Ca2+ store
sites may account for the facilitation of mobilization-dependent secretion in the presence of
1 µm ouabain. |
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