ISSN:
1432-0878
Keywords:
CA++-ATPase
;
Pituitary gland, pars nervosa
;
Pituicytes
;
Neurosecretion
;
Guinea pig
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary Ca++-ATPase activity (cf. Ando et al. 1981) was examined both light- and electron-microscopically in the neurohypophysis of the guinea pig. Apart from a strong activity within the walls of the blood vessels, in the parenchyma of the neurohypophysis the reaction product of the Ca++-ATPase activity was restricted to the plasmalemma of the pituicytes. This reaction was completely dependent upon Ca++ and the substrate, ATP; the reaction was inhibited by 0.1 mM quercetin, an inhibitor of Ca++-ATPase. A reduction of the enzyme activity occurred by 1) adding Mg++ to the standard incubation medium, and 2) substituting Ca++ with Mg++ at varing concentrations. In all experiments the neurosecretory fibers were devoid of Ca++-ATPase activity. The function of the Ca++-ATPase activity in the plasmalemma of the pituicytes is discussed in connection with the regulation of the extracellular Ca++ concentration, which seems to be important with respect to the discharge of secretory material from the neurosecretory fibers.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00228433
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