Anesthetic, fish

Anesthetics. Ethyl amiaobenzoate [94-09-7] (benzocaiae), C2H22NO2, is the only anesthetic candidate that might allow spawned-out broodstock carcasses to be used for pet or human food. Studies are still required to determine which residues remain ia the carcasses (9). Electronarcosis is an alternative to chemical anesthesia that uses varying electrical frequencies to rapidly anesthetize fishes and allow gentie recovery. Electronarcosis has been used effectively on tilapia (Oreochromis sp.) and the common carp Cyprinus carpid) and the technique is being tested with other fishes (23,24). 

Place embryos in 3-cm Petri dish, in E3 containing 0.1 mg/ ml Tricaine to anesthetize fish. Add chemical compound for pretreatment as in Subheading 3.2, step 2. (Hereafter media will refer to E3 containing Tricaine, with or without compound.) If the effect of the compound is reversible, it can be washed out simply by replacing the compound-containing media with fresh E3. 

Anesthetize sexually mature males by placing them in a 0.002% (w/v) tiicaine solution until gill movement has stopped. Rinse anesthetized fish in water. 

Figure 52. Apparatus for collecting samples from anesthetized fish. Distilled or tap water was pumped over the gills of the experimental fish in the chamber, flowed out the side arm into the two colunms, each containing 10 g ion-exchange resin (IRA 400). The cannula delivered urine into a 10-ml graduated cylinder. To secure the animals in position, damp cotton was tucked in around the tail of the fish. From Hunn and Fromm (1964).

The studies on which we report here were conducted as part of an ongoing program to evaluate the safety of various chemicals (anesthetics, collecting aids, selective toxicants, and a herbicide) that are used on fish, or that are used in the aquatic environment, or are possible contaminants of that environment. 

In a series of studies on 2-amino-A-phenylthiazole (Piscaine), a fish anesthetic, Suzuki and co-workers (24) isolated and identified an N-glucuronide metabolite (2-amino-A-phenylthiazole-2-N-g-mono-D-glucopyranosiduronic acid) from medaka (Oryzias latipes), rainbow trout, and carp (Cyprinus oarpio) (Figure l). 

On the basis of studies on the metabolism of the fish anesthetic, methane sulfonate of m-aminobenzoic acid ethyl ester (MS-222), by a shark (the spiny dogfish, Squalus aeanthias), Maren et al. (25) reported the formation of a metabolite, m-aminobenzoic acid, by cleavage of the ester bond (Figure 1). This ester-hydrolyzed product was not partitioned across the gill, but was slowly excreted by the kidney. 

Fish also metabolize xenobiotics by N-acetylation. This process is well documented for the fish anesthetic MS-222 (26-30). 

Fish rapidly eliminate residues of MS-222 after exposure to the anesthetic (27). Blood, kidney, liver, and muscle show different rates of elimination, which probably reflect the form of the drug present and fluid turnover times in the tissues. The concentration of the anesthetic in these tissues decreased to the detection limit of their method within 5 h. 

Suzuki et al. (24) identified a minor biotransformation product of 2-amino- -phenylthiazole in rainbow trout and carp as 2-acetamido-it-(V-hydroxyphenyl )-thiazole (Figure 1). They were unable, however, to demonstrate the presence of this metabolite in the medaka. These authors also suggested that the effectiveness of the 2-amino-A-phenylthiazole as a fish anesthetic is related to the rate at which the drug is activated by biotransformation. 

The attenuated clearance of BSP observed in MCB or CCI4 treated fish may be due to factors unrelated to liver dysfunction. For example, anesthetic effects associated with CCI4 or MCB intoxication may have influenced plasma clearance of BSP... 

Puffer fish Fugu spp. Tetrodotoxin (found in Vibrio, Pseudomonas spp.) Alkaloid Predators. Local anesthetic (5-30 minutes) death in 6-24 hours (60% mortality)... 

The odors of amines are quite unpleasant many of the malodorous compounds that are released as fish decay are low-molecular-weight amines. Amines of high molecular weight are nonvolatile, so they have little odor. One of the materials used to manufacture nylon, hexamethylenediamine, is an aliphatic amine. Many aromatic amines are used to prepare organic dyes that are widely used in industrial societies. Amines are also used to produce many medicinal products, including local anesthetics and sulfa drags. 

Anesthetics. The use of anesthetics or sedatives for restraint in sampling or cannulation procedures can, as in mammals, cause difficulties when used in conjunction with pharmacokinetic and metabolic studies. Anesthesia with MS-222, one of the most common fish anesthetics, has been shown under certain... 

Tricaine methanesulfonate (MS-222). Tricaine methanesulfonate (3-aminobenzoic acid ethyl ester methanesulfonate MS-222) is widely used for the sedation and anesthetization of fish. The compound is 0.01% ionized at body pH and has a partition coefficient of 312. This relatively nonpolar lipophilic drug is rapidly absorbed from water and eliminated in freshwater and marine fish species. 

Rice SA, Fish KJ. Anesthetic metabolism and renal function in obese and nonobese Fischer 344 rats following enflurane or isoflurane anesthesia. Anesthesiology 1986 65 28-34. 

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