Octreotide induces a negative water balance in healthy and cirrhotic rats during a salt load without changing arterial or portal pressure . Dep. of liver and pancreatic diseases, K.U. Leuven, UZ Gasthuisberg, Leuven, Belgium

SUMMARYWe measured the salt and water balance of hatchling leatherback sea turtles, Dermochelys coriacea, during their first few days of life to investigate how they maintain homeostasis under the osmoregulatory challenge of a highly desiccating terrestrial environment and then a hyperosmotic marine environment. Hatchlings desiccated rapidly when denied access to sea water,with their hematocrit increasing significantly from 30.32±0.54 % to 38.51±1.35 % and plasma Na+ concentration increasing significantly from 138.2±3.3 to 166.2±11.2 mmoll-1 in 12 h. When hatchlings were subsequently put into sea water, hematocrit decreased and plasma Na+ concentration was unchanged but both were significantly elevated above pretreatment values. In other hatchlings kept in sea water for 48 h, body mass and plasma Na+ concentration increased significantly, but hematocrit did not increase. These data show that hatchlings were able to osmoregulate effectively and gain mass by drinking sea water. We stimulated hatchlings to secrete salt from the salt glands by injecting a salt load of 27 mmol kg-1. The time taken for secretion to begin in newly hatched turtles was longer than that in 4-day-old hatchlings, but the secretory response was identical at 4.15±0.40 and 4.13±0.59 mmol Na+ kg-1 h-1respectively. Adrenaline and methacholine were both potent inhibitors of salt gland secretion in a dose-dependent manner, although methacholine administered simultaneously with a subthreshold salt load elicited a transient secretory response. The results showed that hatchling leatherbacks are able to tolerate significant changes in internal composition and efficiently use their salt glands to establish internal ionic and water balance when in sea water.

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Some observations on ion and water balance in the puffin, Fratercula arctica

Canadian Journal of Zoology ◽

10.1139/z70-081 ◽

1970 ◽

Vol 48 (3) ◽

pp. 479-482 ◽

Cited By ~ 2

Author(s):

Maryanne Robinson Hughes

Keyword(s):

Body Weight ◽

Water Balance ◽

Solid Material ◽

The Body ◽

Plasma Sodium ◽

Salt Glands ◽

Mean Values ◽

Salt Load ◽

Fratercula Arctica ◽

The Mean

The mean values for six adult puffins were hematocrit, 0.511 ± 0.007; plasma sodium, 160.7 ± 2.3, potassium, 3.1 ± 0.1, and chloride, 133.4 ± 1.9 meq/l.The cloacal fluid of one young laboratory-reared puffin was always hypotonic to the plasma in Na and Cl and never contained more than one-half the ingested Na, K, or Cl; contained less than 40% of the ingested water; and solid material was less than 10% of the total as determined by dry weight.In one salt load experiment (4.0 ml 1.0 N NaCl/3 92-gram adult) the salt glands proved very efficient, producing a secretion of 975 meq/l (maximum) Cl and eliminating 75% of the load in 20 min. The salt glands and kidneys are large, 0.1% and 1.8% of the body weight respectively.

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