Whole-body autoradiography and microautoradiography in eels after
intra-arterial administration of 125i-eel anp.
Sakaguchi, Hajime, Hiroyuki Suzuki, Hiromi Hagiwara, Hiroyuki Kaiya,
Yoshio Takei, Masayuki Ito, Sadami Shibabe, and Shigehisa Hirose.
Department of Biological Sciences and Research Center of
Experimental Biology, Tokyo Institute of Technology, Yokohama 226;
Laboratory of Physiology, Ocean Research Institute, University of
Tokyo, Tokyo 164; and Radioisotope School, Nuclear Education Center,
Japan Atomic Energy Research Institute, Tokyo 113, Japan
APStracts 3:0128R, 1996.
125I-labeled eel atrial natriuretic peptide (ANP) was administered
into the ventral or dorsal aorta of freshwater (FW) and seawater (SW)
eels, Anguilla japonica, and its major target organs were explored by
whole-body autoradiography. Localization of the ANP binding in the
target organs was also examined at tissue and cell levels by
microautoradiography using tissue sections. Whole-body
autoradiography revealed that the specific label was accumulated
predominantly in the gill, with lesser amounts in the atrium, kidney,
liver, and urinary bladder. Autoradiographic grains were most dense
in the secondary lamellae of the gill, particularly on the side of
the efferent filamental artery. Other binding sites in target tissues
were the glomerulus of the kidney, epicardium and endocardium of the
atrium, bile duct/blood vessels of the liver, and interrenal cells of
the head kidney. There was no difference in the distribution and
density of grains between injections into the ventral aorta and
dorsal aorta, although, in the former, injected 125I-labeled eel ANP
passes through the gill before reaching peripheral target tissues.
There was a tendency for down-regulation of ANP binding sites in SW
eels, especially in the gill. These results show that specific ANP
binding sites are present in organs which are implicated in
osmoregulation and cardiovascular regulation in eels, and further
suggest that the number of ANP binding sites varies according to
changes in the environmental salinity.
Received 28 November 1995; accepted in final form 26 March 1996.
APS Manuscript Number R749-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 16 April 96