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Residue dynamics of quinaldine and TFM in rainbow trout

Study of the residue dynamics of 2-methylquinoline (quinaldine) and 3-trifluoromethyl-4-nitrophenol (TFM) in rainbow trout yielded the following findings: 1. Uptake and distribution of TFM by trout was influenced by the biotransformation of the lipidsoluble free phenol. No such effect was observed with quinaldine. 2. Disappearance of quinaldine and TFM from gallbladder bile was slower than from plasma or muscle during 24 hr of withdrawal in fresh water. 3. The concentration of TFM conjugate may exceed that of free TFM in bile by a factor of 10 3 .

General Pharmacology

Organophosphate inhibition of avian salt gland Na, K-ATPase activity

1. Adult black ducks ( Anas rubripes ) were given freshwater or saltwater (1.5% NaCl) for 11 days and half of each group was also given an organophosphate (17 p.p.m. fenthion) in the diet on days 6–11. 2. After 11 days, ducks drinking saltrwater had lost more weight and had higher plasma Na and uric acid concentration and osmolalities than birds drinking freshwater. 3. Saltwater treatment stimulated the salt gland to increased weight and Na, K-ATPase activity. 4. Fenthion generally reduced plasma and brain cholinesterase activity and depressed cholinesterase and Na, K-ATPase activities in salt glands of birds drinking saltwater.

Comparative Biochemistry and Physiology, Part C: C

Comparative cardiovascular effects of four fishery anesthetics in spinally transected rainbow trout, oncorhynchus mykiss

1. We compared the effects of four anesthetics on heart rate, dorsal and ventral aortic blood pressure, and electrocardiograms of rainbow trout ( Oncorhynchus mykiss ). 2. Exposure to the local anesthetics tricaine methanesulfonate (MS-222) and benzocaine hydrochloride (BZH) produced minimal cardiovascular alterations. Mean dorsal aortic pressure (DAP) decreased during exposure to MS-222, and mean DAP and mean ventral aortic pressure (VAP) increased 15% during recovery from BZH. 3. Exposure to the general anesthetic 2-phenoxyethanol (2-PE) or the hypnotic agent etomidate (ET) dramatically decreased heart rate and blood pressures and altered EKG patterns. 4. During recovery, VAP and DAP increased above baseline for an extended period. Heart rate and EKG patterns rapidly returned to normal.

Comparative Biochemistry and Physiology, Part C: C

Embryotoxic effects of crude oil in mallard ducks and chicks

Recent studies in this laboratory have revealed that surface applications of microliter amounts of some crude and fuel oils that coat less than 10% of the egg surface reduce hatching considerably in different avian species. Applications of paraffin compounds that coat equal areas of the egg surface do not reduce hatching suggesting that toxicity is due to causes other than asphyxia. In the present study, 1–10 μl of South Louisiana crude oil, an API reference oil, were applied to the surface of fertile mallard ( Anas platyrhynchos ) and chicken ( Gallus gallus ) eggs. Early embryolethality was greater in mallard embryos than in chick embryos, but later embryolethality that coincided with the time of rapid outgrowth of the chorioallantoic membrane was more prevalent in chick embryos. The overall incidence of embryolethality was similar in both species. Retardation of growth as reflected by embryonic body weight, crown-rump length, beak length, and general appearance was more pronounced in chick than mallard embryos. Teratogenic defects were more frequent in chick embryos, and incomplete or abnormal ossification of the skull was the most common. External application of equivalent amounts of a mixture of paraffin compounds present in crude oil had virtually no embryotoxic effects in either species, suggesting that other components including aromatic hydrocarbons and organometallics may cause the embryotoxicity.

Toxicology and Applied Pharmacology

Regional cholinesterase activity in white-throated sparrow brain is differentially affected by acephate (Orthene®)

Effects of a 14-day dietary exposure to an organophosphorus pesticide, acephate (acetylphosphoramidothioic acid O,S-dimethyl ester), were determined on cholinesterase activity in three regions (basal ganglia, hippocampus, and hypothalamus) of the white-throated sparrow, Zonotrichia albicollis , brain. All three regions experienced depressed cholinesterase activity between 0.5–2 ppm acephate. The regions exhibited cholinesterase recovery at 2–16 ppm acephate; however, cholinesterase activity dropped and showed no recovery at higher dietary levels (>16 ppm acephate). Evidence indicates that the recovery is initiated by the magnitude of depression, not the duration. In general, as acephate concentration increased, differences in ChE activity among brain regions decreased. Three terms are introduced to describe ChE response to acephate exposure: 1) ChE resistance threshold, 2) ChE compensation threshold, and 3) ChE depression threshold. It is hypothesized that adverse effects to birds in the field may occur at pesticide exposure levels customarily considered negligible.

Comparative Biochemistry and Physiology, Part C: P

Drug metabolism in birds

Papers published over 100 years since the beginning of the scientific study of drug metabolism in birds were reviewed. Birds were found to be able to accomplish more than 20 general biotransformation reactions in both functionalization and conjugation. Chickens were the primary subject of study but over 30 species of birds were used. Large species differences in drug metabolism exist between birds and mammals as well as between various birds, these differences were mostly quantitative. Qualitative differences were rare. On the whole, drug metabolism studies in birds have been neglected as compared with similar studies on insects and mammals. The uniqueness of birds and the advantages of using birds in drug metabolism studies are discussed. Possible future studies of drug metabolism in birds are recommended.

Pharmacology

Testing of selected pharmacological agents for capturing waterfowl [Annual Progress Report]

The response of game-farm mallards (Frost strain) to seven pharmacological immobilizing agents was evaluated in Phase I of a planned four-phase study. A limited amount of testing was also done with wild mallards. Single dosages were administered to determine the mean effective dose (ED50) and mean lethal dose (LD50), The therapeutic index, or safety factor (LD50/ED50), and palatability were also established. Optimum dosage rates of compounds administered orally on baits were not considered in this phase of the study. Compounds were-administered by intubation and calculated in terms of mg/kg. All except one compound produced narcosis within 5 minutes at the effective dose rate.Immobilization periods for the seven compounds ranged from 7-24 minutes, and recovery periods from 1.0-6.5 hours. Such wide variations in actions of the compounds can be attributed to a compound's rate of absorption, the ease with which it passes the blood-brain barrier, its solubility in tissues, and its rate of metabolism in the liver and kidneys. Length of both the immobilization and recovery periods were extended when dosages were increased. There was no delayed mortality among survivors with any of the seven compounds at either the ED50 or LD50. Females were generally more sensitive to the anesthetizing agents than males. The ED50 for wild mallards was substantially higher than that for the experimental game-farm birds for the two compounds on which this was tested.Tribromoethanol (Avertin of Winthrop Laboratories) satisfied all test criteria an Phase I and will be subjected to more intensive investigation in ensuing tests. Thiopental sodium (Pentothal of Amdal Company) and pentobarbital sodium (Nembutal of Abbott Laboratories) were judged to be marginal. Although their therapeutic indexes were good (5.00), recovery periods were prolonged and toxic convulsions occurred at medium to high dose rates as the LD50 was approached.Alpha-chloralose (Fisher Scientific) proved least promising of the seven compounds, mainly because of its unacceptable therapeutic index (2.25) and because it possesses prolonged induction and recovery periods. Two new experimental drugs, methoxymol and metomidate (Pitman-Moore), appeared effective and safe when administered by intubation but produced a taste aversion when added to bait. Rejection because of taste was also a problem with secobarbital (Seconal of Elanco Products), and its therapeutic index of 2.75 was unacceptable. Monitoring of heart and respiratory rates, and body temperature by telemetry showed promise as a technique for determining physiological response to drug action.

Report

Intra-strain dioxin sensitivity and morphometric effects in swim-up rainbow trout ( Oncorhynchus mykiss )

Inter and intra-specific differences in sensitivity of early life stage salmonids to 2,3,7,8-TCDD exposure have been reported, but intra-strain differences have not been found in the literature. Our results indicate that intra-strain variability in terms of embryo mortality (LD50) is small in Eagle Lake strain of rainbow trout, LD50 values ranging from 285 to 457 pg TCDD egg g −1 . These results confirm Eagle Lake as a less sensitive strain within rainbow trout, and do not indicate overlap with reported LD50 values for brook or lake trout. Our results also demonstrate that although generalized edema in regions including the yolk-sac are frequently associated with mortality following dioxin exposure, not all edematous fish die. We detected dose-dependent decreases in cranial length, eye diameter, mass, and total length ( P <0.05) in viable swim-up rainbow trout. These effects are presumed to indicate more subtle dose-dependent disruptions of the viteline vein vasculature and, therefore, in access to energy sources. A tendency for dose-dependent decrease in liver glycogen reserves concurred with previous results on salmonids and with the well described TCDD-induced alterations in intermediate metabolism of rats and chicken embryos (wasting syndrome). This syndrome could be contributing to the reduced growth that we observed.

Comparative Biochemistry and Physiology, Part C: T