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1.
J Environ Biol ; 2004 Jan; 25(1): 7-10
Artículo en Inglés | IMSEAR | ID: sea-113555

RESUMEN

Ammonia is the main nitrogenous waste material excreted by gills, then is oxided first to nitrite and then to nitrate. The proportion of ionized-un-ionized ammonia depends on pH and temperature, when this variables increase in a solution containing ammonia the equation goes to left, so the proportion of NH3 increases and the solution becomes more toxic. The purpose of this study was to investigate the acute lethal effects of elevated pH and ammonia on tambaqui juveniles. With a constant ammonia concentration of 5.0 mg/l NH3, there was no mortality a pH of 6.0 (control) and 7.0; but was of 10-20% a pH of 8.0 and 100% at 9.0. The lethal effects of elevated pH and un-ionized ammonia should be recognized as a potential factor contributing to the variable success of tambaqui production ponds, but this species is highly resistant in comparison with other freshwater fish.


Asunto(s)
Factores de Edad , Amoníaco/química , Animales , Líquidos Corporales/efectos de los fármacos , Peces , Agua Dulce , Branquias/efectos de los fármacos , Concentración de Iones de Hidrógeno , Iones , Dosificación Letal Mediana , Compuestos de Nitrógeno/metabolismo , Contaminantes del Agua/toxicidad
2.
J Environ Biol ; 2002 Jul; 23(3): 225-9
Artículo en Inglés | IMSEAR | ID: sea-113875

RESUMEN

The objective was to determine the plasmatic enzyme cholinesterase recovery, after being inhibited by an organophosphorous in juveniles of Prochilodus lineatus. Fish were exposed 12 h to a sublethal concentration of 1 mg/l of monocrotophos, and immediately placing in clean water during 12, 24, 48 and 96 h to detoxification. After this period, blood was extracted and plasma were used for the quantification of cholinesterase. The results showed a enzymatic inhibition of 91.9%, 55.1%, 50.4% and 33.4% with 12, 24, 48 and 96 h of recovery, respectively. The enzymatic activity spreads to be normalized with the course of hours and the degree of inhibition obtained initially was very high and sustained in the first 48 h.


Asunto(s)
Adaptación Fisiológica , Animales , Colinesterasas/farmacología , Relación Dosis-Respuesta a Droga , Exposición a Riesgos Ambientales , Peces/fisiología , Insecticidas/efectos adversos , Compuestos Organofosforados
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