Regulation of water movement across vertebrate renal tubules

Nishimura, Hiroko; Fan, Zheng

doi:10.1016/s1095-6433(03)00162-4

Cited by 70 publications

(39 citation statements)

References 62 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Active ion reabsorption is often coupled to an osmotic water transport to the blood, depending on the water permeability of the urinary epithelium. The collecting ducts are lined by a membrane impermeable to water, and the rate of water transport depends on hormonal stimulation, on the presence of aquaporins and on the rate of water delivery by the nephrons (reviewed by Nishimura and Fan, 2003). In FW teleosts, the water permeability of the collecting ducts is very low (Nishimura et al, 1983).…”

Section: Discussionmentioning

confidence: 99%

Differential freshwater adaptation in juvenile sea-bassDicentrarchus labrax: involvement of gills and urinary system

Nebel¹,

Romestand²,

Nègre-Sadargues³

et al. 2005

Journal of Experimental Biology

View full text Add to dashboard Cite

SUMMARY The effects of long-term freshwater acclimatization were investigated in juvenile sea-bass Dicentrarchus labrax to determine whether all sea-bass juveniles are able to live in freshwater and to investigate the physiological basis of a successful adaptation to freshwater. This study particularly focused on the ability of sea-bass to maintain their hydromineral balance in freshwater and on their ion (re)absorbing abilities through the gills and kidneys. Two different responses were recorded after a long-term freshwater acclimatization. (1) Successfully adapted sea-bass displayed standard behavior; their blood osmolality was maintained almost constant after the freshwater challenge, attesting to their efficient hyperosmoregulation. Their branchial and renal Na+/K+-ATPase abundance and activity were high compared to seawater fish due to a high number of branchial ionocytes and to the involvement of the urinary system in active ion reabsorption, producing hypotonic urine. (2) Sea-bass that had not successfully adapted to freshwater were recognized by abnormal schooling behavior. Their blood osmolality was low (30% lower than in the successfully adapted sea-bass), which is a sign of acute osmoregulatory failure. High branchial Na+/K+-ATPase abundance and activity compared to successfully adapted fish were coupled to a proliferation of gill chloride cells, whose ultrastructure did not display pathological signs. The large surface used by the gill chloride cells might negatively interfere with respiratory gas exchanges. In their urinary system, enzyme abundance and activity were low, in accordance with the observed lower density of the kidney tubules. Urine was isotonic to blood in unsuccessfully adapted fish, ruling out any participation of the kidney in hyperosmoregulation. The kidney failure seems to generate a compensatory ion absorption through increased gill activity, but net ion loss through urine seems higher than ion absorption by the gills, leading to lower hyper-osmoregulatory performance and to death.

show abstract

Section: Discussionmentioning

confidence: 99%

Differential freshwater adaptation in juvenile sea-bassDicentrarchus labrax: involvement of gills and urinary system

Nebel¹,

Romestand²,

Nègre-Sadargues³

et al. 2005

Journal of Experimental Biology

View full text Add to dashboard Cite

show abstract

“…Cortisol has largely been identified as a SW-adapting hormone, primarily promoting a number of SWadapting functions (25). When administered to FW-acclimated fish, the steroid has been shown to induce epithelial features similar to those of SW fish such as 1) Cl Ϫ cell proliferation and differentiation, with associated increases in the Na ϩ ,K ϩ -ATPase activity (25,49); and 2) an increase in the permeability of ions in the esophagus (24).…”

Section: Discussionmentioning

confidence: 99%

Regulation of expression of two aquaporin homologs in the intestine of the European eel: effects of seawater acclimation and cortisol treatment

Martinez¹,

Cutler²,

Wilson³

et al. 2005

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

Complementary DNAs encoding homologs of the mammalian aquaglyceroporins (termed AQPe) and aquaporin-1 isoforms (termed AQP1) were isolated from the European eel. The AQP amino acid sequences share 35-54% identity with other known human AQPs. Although AQPe mRNA expression was approximately equivalent along the entire length of the gut, AQP1 expression was the highest in the posterior/rectal segment. Seawater (SW) acclimation increased AQP1 mRNA abundance by 5-and 17-fold in the anterior, 14-and 23-fold in the mid-, and 9-and 7-fold in the posterior/rectal gut regions of yellow and silver eels, respectively. SW acclimation had an effect on AQPe mRNA expression only in the midintestine of silver eels, where a small but significant 1.7-fold increase in abundance was measured. Western blots using an eel AQP1-specific antibody identified the presence of a major immunoreactive 28-kDa protein, primarily within the posterior/rectal segment. A 3-wk SW transfer induced an increase in AQP1 protein abundance in all intestinal segments, with the posterior/rectal region still expressing protein levels ϳ40-and 8-fold higher than the anterior and midsegments, respectively. Strong AQP1 immunofluorescence was detected within the vascular endothelium in both freshwater (FW)-and SW-acclimated eels and in the epithelial apical brush border in the posterior/ rectal gut regions of SW-acclimated eels. Cortisol infusion into FW eels had no effect on intestinal AQPe mRNA expression but induced increases in AQP1 mRNA and protein levels. These results provide evidence for the presence of a SW-induced and steroid-regulated AQP water channel pathway within the intestine of the European eel.Anguilla anguilla; gastrointestinal tract; AQP1; AQPe; corticosteroid WHEN FACED WITH EXTERNAL ENVIRONMENTS of varying salinity, euryhaline teleosts, such as the European eel (Anguilla anguilla), have a fundamental osmoregulatory problem: the maintenance of their body fluid composition and osmolality. Osmoregulation is achieved by linked ion and water transport in the gill, kidney, gastrointestinal tract, and urinary bladder (15). The intestine is a major osmoregulatory organ in euryhaline teleost fish, especially when acclimated to seawater (SW). When transferred to the marine environment, euryhaline fish such as the European eel increase their drinking rate by Ͼ10-fold and the ingested SW is mainly desalinated, first within the esophagus, possibly by passive ion diffusion, and thereafter along the entire length of the intestine, by active transport of monovalent ions into the blood. The subsequent water absorption is considered to take place in the intestine by osmotic mechanisms after active absorption of the monovalent ions, the "solute-linked water flow" pathway (52). The magnitude of water fluxes across various parts of the intestine has also been determined, with highest levels occurring in the midregion followed in descending order by the posterior and anterior intestine and rectum (5, 9).Although intestinal salt and water transporters are central t...

show abstract

“…Avp is then released into the blood stream upon appropriate stimulation (e.g., hemorrhage or dehydration) to act at the kidneys and blood vessels (Nishimura and Fan, 2003). The brain also contains several populations of smaller, parvocellular neurons whose projections remain within the brain.…”

Section: Introductionmentioning

confidence: 99%

Vasopressin: Behavioral roles of an “original” neuropeptide

Caldwell

Lee

Macbeth

et al. 2008

Progress in Neurobiology

419

416

View full text Add to dashboard Cite

Vasopressin (Avp) is mainly synthesized in the magnocellular cells of the hypothalamic supraoptic (SON) and paraventricular nuclei (PVN) whose axons project to the posterior pituitary. Avp is then released into the blood stream upon appropriate stimulation (e.g., hemorrhage or dehydration) to act at the kidneys and blood vessels. The brain also contains several populations of smaller, parvocellular neurons whose projections remain within the brain. These populations are located within the PVN, bed nucleus of the stria terminalis (BNST), medial amygdala (MeA) and suprachiasmatic nucleus (SCN).Since the 1950's, research examining the roles of Avp in the brain and periphery has intensified. The development of specific agonists and antagonists for Avp receptors has allowed for a better elucidation of its contributions to physiology and behavior. Anatomical, pharmacological and transgenic, including "knockout," animal studies, have implicated Avp in the regulation of various social behaviors across species.Avp plays a prominent role in the regulation of aggression, generally of facilitating or promoting it. Affiliation and certain aspects of pair-bonding are also influenced by Avp. Memory, one of the first brain functions of Avp that was investigated, has been implicated especially strongly in social recognition. The roles of Avp in stress, anxiety, and depressive states are areas of active exploration. In this review, we concentrate on the scientific progress that has been made on understanding the role of Avp in regulating of these and other behaviors across species, as well as discuss the implications for human behavior.

show abstract

Regulation of water movement across vertebrate renal tubules

Cited by 70 publications

References 62 publications

Differential freshwater adaptation in juvenile sea-bassDicentrarchus labrax: involvement of gills and urinary system

Differential freshwater adaptation in juvenile sea-bassDicentrarchus labrax: involvement of gills and urinary system

Regulation of expression of two aquaporin homologs in the intestine of the European eel: effects of seawater acclimation and cortisol treatment

Vasopressin: Behavioral roles of an “original” neuropeptide

Contact Info

Product

Resources

About