Affiliation:
1. Department of Biology, University of California, Santa Cruz, 95064,USA
2. Neuroendocrinology Laboratory, Division of Life Science, NASA Ames Research Center, Moffett Field, CA 94035, USA
Abstract
SUMMARYThe physiological actions of vasopressin (VP) in marine mammals are not well defined. To help elucidate its hormonal and renal effects in this group of mammals, northern elephant seal (Mirounga angustirostris) pups(N=7; 99±4 kg) were first infused with 0.9% saline (control;220 ml), followed 24 h later with VP (as a 20 ng kg-1 bolus, then 2 ng kg-1 min-1 for approximately 35 min in 225±16 ml saline). During both control and VP periods, blood samples were collected prior to infusion, and 15, 30, 60, 120 min and 24 h after infusion to examine the hormonal responses of the pups to VP. Renal responses were quantified from 24 h urine samples obtained prior to infusion (control) and 24 h post-infusion. Compared to the control period, infusion of VP increased plasma concentrations of cortisol over a 120 min period and aldosterone over 30 min,while plasma renin activity (PRA) was decreased for a 120 min period. The plasma urea:creatinine ratio was elevated following infusion of VP. Urine output and osmotic clearance were increased by 69±18% (mean ± s.e.m.) and 36±10%, respectively, but free water clearance and glomerular filtration rate were not significantly altered 24 h post-infusion of VP. Solute (osmolality, Na+, K+ and Cl-) excretion and fractional excretion of electrolytes were also increased when compared to control values. The increase in cortisol concentration suggests that VP may possess corticotropin releasing hormone-like activity in elephant seals. If osmotic diuresis and natriuresis are typical consequences of elevated [VP] in fasting pups, then not increasing VP normally during the fast may serve as a protective mechanism to avoid the potential loss of Na+ induced by elevated [VP]. Therefore, under natural fasting conditions, pups may be highly sensitive to small changes in[VP], resulting in the maintenance of water and electrolyte balance.
Publisher
The Company of Biologists
Subject
Insect Science,Molecular Biology,Animal Science and Zoology,Aquatic Science,Physiology,Ecology, Evolution, Behavior and Systematics
Reference41 articles.
1. Aguilera, G. and Rabadan-Diehl, C. (2000). Vasopressinergic regulation of the hypothalamic-pituitary-adrenal axis:implications for stress adaptation. Reg. Peptides96, 23-29.
2. Bie, P., Munksdorf, M. and Warberg, J. (1984). Renal effects of overhydration during vasopressin infusion in conscious dogs. Am. J. Physiol.247(
3. Bouby, N., Ahloulay, M., Nsegbe, E., Déchaux, M.,Schmitt, F. and Bankir, L. (1996). Vasopressin increases glomerular filtration rate in conscious rats through its antidiuretic action. J. Am. Soc. Nephrol.7,842-851.
4. Bradley, S. E., Mudge, G. H. and Blake, W. D.(1954). The renal excretion of sodium, potassium, and water by the harbor seal (Phoca vitulina L.): effect of apnea; sodium,potassium, and water loading; pitressin; and mercurial diuresis. J. Cell. Comp. Physiol. B157,445-449.
5. Brooks, A. N. and Challis, J. R. G. (1989). Effects of CRF, AVP and opioid peptides on pituitary-adrenal responses in sheep. Peptides10,1291-1294.
Cited by
11 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献