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Hormonal control of salt and water balance in vertebrates

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Abstract

The endocrine system mediates many of the physiological responses to the homeostatic and acclimation demands of salt and water transport. Many of the hormones involved in the control of salt and water transport are common to all vertebrates, although their precise function and target tissues have changed during evolution. Arginine vasopressin (vasotocin), angiotensin II, natriuretic peptides, vasoactive intestinal peptide, urotensin II, insulin and non-genomic actions of corticosteroids are involved in acute (minutes and hours) alterations in ion and water transport. This rapid alteration in transport is primarily the result changes in behavior, blood flow to osmoregulatory organs, and membrane insertion or activation (e.g., phosphorylation) of existing transport proteins, ion and water channels, contransporters and pumps. Corticosteroids (through genomic actions), prolactin, growth hormone, and insulin-like growth factor I primarily control long-term (several hours to days) changes in transport capacity that are the result of synthesis of new transport proteins, cell proliferation, and differentiation. In addition to the important task of establishing broad evolutionary patterns in hormones involved in ion regulation, comparative endocrinology can determine species and population level differences in signaling pathways that may be critical for adaptation to extreme or rapidly changing environments.

Section snippets

Physiological requirements for salt and water transport

Maintenance of constant intracellular and extracellular ionic and osmotic conditions (Bernard’s constancy of ‘le milieu intérieur’) is critical for the normal functioning of cells. With several notable exceptions, such as hagfish, sharks and ureotelic marine frogs, the majority of vertebrates maintain a remarkably similar salt content of their extracellular fluid, approximately one-third that of seawater. This basic strategy results in different transport demands for vertebrates depending on

Acute endocrine responses

Most organisms have at least a limited capacity to respond to an osmotic or ionic challenge by rapidly changing existing transport mechanism. Some of these may be independent of hormones (autoregulatory), such as changes in ion availability to transporters. Most changes in ion transport, however, are cued by neuroendocrine or endocrine factors. Although there is a continuum of temporal responses, we can roughly divide transport responses into those that activate existing transport mechanisms

Acclimation endocrine responses

Acclimation responses increase the overall capacity of an organism to perform a physiological function. The acclimation response is similar or identical to phenotypic plasticity; its presence or absence will often determine the capacity of an animal to live in certain habitats and thus determine the ecological limits of species’ distributions. A classic example of acclimation in human physiology is the increased capacity for oxygen extraction after exposure to high altitudes. This occurs over a

Summary and perspectives

In this review we have summarized the acute and acclimation endocrine responses that regulate physiological responses to osmotic challenges. Acute responses are rapid (seconds to hours) and are the result of activation of existing transport mechanisms. Examples of acute regulation include behavioral changes such as drinking, altered blood flow, insertion of transporters into the plasma membrane, and phosphorylation of transporters. Acclimation responses occur over hours and days and are the

References (36)

  • W.G. Anderson et al.

    The effects of environmental salinity on circulating levels of ANG II, CNP and AVT in the euryhaline elasmobranch, Carcharhinus leucas

    Gen. Comp. Endocrinol.

    (2006)
  • R.J. Balment et al.

    Arginine vasotocin and fish osmoregulation

    Fish Physiol. Biochem.

    (1993)
  • R.J. Balment et al.

    Arginine vasotocin a key hormone in fish salt and water balance and many other aspects of physiology and behaviour

    Gen. Comp. Endocrinol.

    (2006)
  • P.J. Bentley

    Comparative Vertebrate Endocrinology

    (1998)
  • S.D. Bradshaw

    Homeostasis in Desert Reptiles

    (1997)
  • N. Charrel et al.

    Biochemical characterisation and immunohistochemical localization of urotensin II in the human brainstem and spinal cord

    J. Neurochem.

    (2004)
  • Donald, J.A., Trajanovska, 2006. A perspective on the role of natriuretic peptides in amphibian osmoregulaton. Gen....
  • Goldstein, D.L., 2006. Regulation of the avian kidney by arginine vasotocin. Gen. Comp. Endocrinol. (this volume)....
  • Cited by (221)

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