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Angiotensin-stimulated drinking in marine fish
The American Journal of Physiology
|June 1, 1986
Summary
Marine fish drinking is stimulated by angiotensin II (ANG II) and hemorrhage, similar to mammals. Freshwater fish showed no such response, indicating differences in osmoregulation and fluid balance control.
Area of Science:
- Comparative Physiology
- Osmoregulation
- Animal Behavior
Background:
- Drinking behavior is crucial for fluid balance in fish.
- Angiotensin II (ANG II) is known to stimulate drinking in mammals.
- Understanding drinking regulation in marine versus freshwater fish is key to osmoregulation.
Purpose of the Study:
- To investigate drinking rates in marine and freshwater fish.
- To determine the effect of angiotensin II (ANG II) and hemorrhage on fish drinking.
- To compare drinking responses between marine and freshwater stenohaline species.
Main Methods:
- Measuring polyethylene glycol ingestion to quantify drinking rates.
- Utilizing marine (long-horned sculpin, flounder) and freshwater (goldfish, mottled sculpin, common shiner) species.
- Administering intramuscular injections of ANG II and inducing hemorrhage.
Main Results:
- Marine fish exhibited higher basal drinking rates than freshwater fish.
- ANG II and hemorrhage significantly stimulated drinking in marine species (2-3 fold and 6-10 fold, respectively).
- Freshwater species showed no significant change in drinking rates following ANG II injection or hemorrhage.
Conclusions:
- Exogenous ANG II and hemorrhage stimulate drinking in marine stenohaline fish, mirroring mammalian responses.
- Freshwater stenohaline fish lack these ANG II and hemorrhage-induced drinking responses.
- Blocking endogenous ANG II did not affect basal or hemorrhage-stimulated drinking in marine fish, suggesting complex regulatory pathways.