In:
Journal of Experimental Biology, The Company of Biologists, Vol. 200, No. 13 ( 1997-07-01), p. 1895-1904
Abstract:
Chronic salt stress in ducklings (Anas platyrhynchos) resulted in a sustained accumulation of cyclic AMP in the secretory cells of the nasal salt glands. Adaptive increases in the activity of the Na+/K+-ATPase, measured as ATP hydrolysis rates in freshly isolated tissue, were observed after 12 h of salt stress. This change in enzyme activity was associated with increases in protein abundance in the α-as well as in the β-subunit of Na+/K+-ATPase and an increase in β-subunit glycosylation. We investigated whether the increase in the cytosolic cyclic AMP concentration and the adaptive changes in Na+/K+-ATPase activity were causally related. Using an organotypic tissue culture system for salt gland slices from unstressed (naive) ducklings, we produced similar changes in Na+/K+-ATPase activity and subunit abundance by treating cultured tissue with drugs that elevate cytosolic cyclic AMP levels (forskolin, 8-CPT-cAMP) during a 15 h culture period. Protein synthesis assays using cultured tissue revealed that elevations in cytosolic cyclic AMP level mediate increases in Na+/K+-ATPase subunit abundance by slowing down the degradation of ATPase subunits. This increase in the amount of enzyme protein was associated with a significant increase in Na+/K+-ATPase activity in tissue homogenates. The time course of these changes in cyclic-AMP-treated cultured tissue resembled that observed in salt-stressed intact animals, indicating that the elevation in cyclic AMP level in salt gland tissue may constitute a portion of the signalling events ultimately leading to the adaptive increase in Na+/K+-ATPase activity in vivo.
Type of Medium:
Online Resource
ISSN:
0022-0949
,
1477-9145
DOI:
10.1242/jeb.200.13.1895
Language:
English
Publisher:
The Company of Biologists
Publication Date:
1997
detail.hit.zdb_id:
1482461-9
SSG:
12
Bookmarklink