32 33 Hagfishes are the most ancient of the extant craniates, and demonstrate a 34 high tolerance for a number of unfavorable environmental conditions including 35 elevated ammonia. Proposed mechanisms of ammonia excretion in aquatic 36 organisms include vesicular NH4+ transport and release by exocytosis in marine 37 crabs, and passive NH3 diffusion, active NH4+ transport and paracellular leaka...

HIGHLIGHTS Fluoxetine increases the metabolic rate and excretion of ammonia in both species. O:N ratio fish showed higher values highest concentrations fluoxetine. The LC50 - 96 hour Palaemon pandaliformis represented greater toxicity. Both species are a good biological model for fluoxetine exposure studies.

The freshwater snakehead Channa asiatica is an obligatory air-breather that resides in slow-flowing streams and in crevices near riverbanks in Southern China. In its natural habitat, it may encounter bouts of aerial exposure during the dry seasons. In the laboratory, the ammonia excretion rate of C. asiatica exposed to terrestrial conditions in a 12 h:12 h dark:light regime was one quarter that...

Fishes, in general, follow ammonotelic mode of excretion. However, certain stress factors may provoke them to excrete urea. In the present study, the possible role of ureogenesis to avoid accumulation of toxic ammonia under water-restricted condition was tested in Heteropneustes fossilis. A total of hundred fishes were collected and sacrificed. Excretory urea and ammonia were estimated in the w...

Among the various physiological-biochemical changes associated with the invasion of land from an aquatic environment is that dealing with the nature of the nitrogen excretion product of protein and amino acid catabolism. In general terms (l-4), the excretion of ammonia (ammonotelism), urea (ureotelism), or uric acid (uricotelism) is related to the availability of water to an organism. Ammonia c...

Handling of electrolytes and acidic equivalents by the antennal gland was monitored in freshwater crayfish (Pacifastacus leniusculus) during control normoxia (Po 2 = 148mmHg; 1 mmHg = 133-3Pa), 72h of hyperoxia (Po2 = 500mmHg) and 24 h of recovery. A preparation was developed for direct collection of urinary flow (UFR) which was confirmed using inulin clearance (CIN). Renal effluxes of Na + , C...

Among the various physiological-biochemical changes associated with the invasion of land from an aquatic environment is that dealing with the nature of the nitrogen excretion product of protein and amino acid catabolism. In general terms (l-4), the excretion of ammonia (ammonotelism), urea (ureotelism), or uric acid (uricotelism) is related to the availability of water to an organism. Ammonia c...

HE RECENT EMPHASIS on disorders of acid-base metabolism has necessitated a reappraisal of those urinary constituents which represent elimination of acid or base. The conventional expression for urinary acid excretion (“net acid excretion”) is titratable acid bicarbonate + ammonia (T.A. CO2 + NH4 ) (1). It has been the contention of this laboratory that acid excretion is more inclusively represe...

Effects of increased ammonia and/or arginine absorption across the portal-drained viscera (PDV) on net splanchnic (PDV and liver) metabolism of nitrogenous compounds and urinary N excretion were investigated in six catheterized Hereford x Angus steers (501 +/- 1 kg BW) fed a 75% alfalfa:25% (as-fed basis) corn-soybean meal diet (0.523 MJ of ME/[kg BW(0.75).d]) every 2 h without (27.0 g of N/kg ...

Digestion affects nitrogen metabolism in fish, as both exogenous and endogenous proteins and amino acids are catabolized, liberating ammonia in the process. Here we present a model of local detoxification of ammonia by the intestinal tissue of the plainfin midshipman (Porichthys notatus) during digestion, resulting in an increase in urea excretion of gastrointestinal origin. Corroborating evide...