Expression of na+,k+-atpase in the brown trout, salmo trutta: in
vivo modulation by hormones and seawater.
Madsen, Steffen S., Mette K. Jensen, Jane Nohr, and Karsten
Kristiansen.
Institute of Biology and Department of Molecular Biology, Odense
University, Campusvej 55, DK-5230 Odense M, Denmark; Department of
Integrative Biology, University of California at Berkeley, Berkeley,
CA 94720, U.S.A.
APStracts 2:0173R, 1995.
Expression of the Na+,K+-ATPase -subunit was investigated in the gill
and trunk kidney of Salmo trutta. Groups of freshwater (FW) fish were
treated with various hormones (cortisol (F): 3 x 4.0 g g-1;
recombinant salmon growth hormone (rsGH): 3 x 0.25 g g-1; salmon
prolactin (sPRL): 3 x 0.25 g g-1; recombinant bovine insulin-like
growth factor-I (rbIGF-I): 2 x 0.01 g g-1 or 2 x 0.1 g g-1), or
transferred to 25 ppt seawater (SW) and sampled after 1,2,3 and 50
days. Total RNA was analysed by Northern blotting using Xenopus
laevis Na+,K+-ATPase -subunit cDNA as probe. The probe detected a 3.8
kb transcript. Relative to untreated FW control fish, the abundance
of -subunit Na+,K+-ATPase mRNA in gill tissue increased 1.7-2.5 fold
after treatment with F, rsGH and rbIGF-I and after transfer to SW.
Na+, K+-ATPase enzyme activity was also significantly stimulated in
these groups, except at 0.01 g g-1 rbIGF-I. sPRL was without effect.
In the kidney, -subunit mRNA level and Na+,K+-ATPase activity were
unaffected by hormone treatment and SW transfer. The results
indicate, that an increased abundance of -subunit mRNA is part of the
molecular mechanism behind the increased gill Na+,K+-ATPase activity
induced by SW-transfer, F, GH and IGF-I.
Received 21 February 1995; accepted in final form 19 June 1995.
APS Manuscript Number R129-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 11 July 1995.