Cardiac, ventilatory and metabolic responses of two ecologically dissimilar species of fish to waterborne cyanide

Abstract

Changes in heart rate, ventilatory activity and oxygen consumption were determined in trout (Salmo gairdneri) and brown bullhead catfish (Ictalurus nebulosus) during exposure to a steadily increasing concentration of waterborne cyanide selected to produce death in 8-9 hours for each species. The lethal cyanide concentration for the bullheads was an order of magnitude higher than for trout. Trout developed an immediate and gradually increasing bradycardia throughout the exposure period. Cyanide produced tachycardia in the bullhead followed by a gradual onset of bradycardia as the concentration of cyanide was raised. Pericardial injection of atropine (a muscarinic cholinergic antagonist) indicated that bradycardia in the trout was due initially to increased vagal tone but later due to the direct effect of cyanide on the heart. Hyperventilation in the trout persisted throughout the exposure period, although the rate and amplitude fluctuated and was variable between individual fish. During the last hour of exposure (highest cyanide concentration), ventilation was characterized by rapid, shallow breaths followed by a sudden respiratory arrest. The bullheads exhibited hyperventilation during the first 3 hours of exposure followed by a gradual, linear drop in ventilation rate and amplitude until death occurred. Cardiac and ventilatory responses in both species were attributed to stimulation of central and peripheral chemoreceptors by cyanide. Evidence is presented which suggests the initial response in the bullheads was due, at least in part, to gustatory stimulation by the cyanide. Oxygen consumption of the trout remained above pre-exposure levels for the majority of the test period. Oxygen consumption in the bullhead paralleled the changes in heart and ventilatory rates. Whole-body lactate levels of fingerlings of both species during cyanide exposure were measured to estimate the extent of anaerobiosis. Whole-body lactate levels were much greater in the bullheads than the trout, indicating a higher capacity for anaerobiosis, possibly due to a greater fuel supply. Overall, the trout responded to cyanide in a manner similar to that produced by environmental hypoxia whereas the bullheads experienced a gustatory stimulus which masked the hypoxia-like response.

Oxygen Flux As an Indicator of Physiological Stress in Fathead Minnow (Pimephales promelas) Embryos: A Real-Time Biomonitoring System of Water Quality

“…This effectively inhibits the final transfer of electrons to oxygen, destroys the mitochondrial membrane potential, and stalls the production of ATP . Brown bullheads ( Ictalurus nebulosus ) exposed to increasing concentrations of cyanide (200−1800 μg/L) over a 9 h period experienced an increase in oxygen consumption and heart rate through 3 h of exposure, followed by a decrease in both parameters until death at 9 h . Brook trout ( Salvelinus fontinalis ) exposed to 5 μg/L cyanide over 29 d had their swimming performance reduced by 50% , while those exposed to 25 μg/L for 5 h underwent an inhibition in oxygen intake .…”

In vitro expansion of autonomously contracting, cardiomyogenic structures from rainbow trout Oncorhynchus mykiss

“…The high regeneration potential and thus high feasibility to generate stable long‐term cultures of fish heart‐muscle cells have great advantages over systems using live animal models. Cell‐based assays to test heart function regarding 1) treatment with metals and other cytotoxics (Sawyer & Heath, 1988), 2) influence of anaesthetics (Hill et al , 2002) and 3) climate change and the implications of changes of abiotic parameters (Gehrke & Fielder, 1988; Hill & Womersley, 1993; Franklin et al , 2001), such as reduced oxygen concentration (Hartmund & Gesser, 1992), changing water temperature (Mitani et al , 1989; Viant et al , 2003) and pH, could provide a plethora of new insights into heart physiology.…”

Oxygen flux as an indicator of physiological stress in aquatic organisms: a real-time biomonitoring system of water quality

“…This effectively inhibits the final transfer of electrons to oxygen, destroys the mitochondrial membrane potential, and stalls the production of ATP [28] . Declines in oxygen consumption have been reported in several studies that have exposed fish to different concentrations of pentachlorphenol (25 -1800 μg/L) fo r different l engths of t ime (5 h -29 d) [30][31][32] . Ou r res ults i ndicate th at s ignificant decre ases i n oxy gen flux b y f athead minnows are detectable within 2 h at con centrations at or abov e 44 μg/L a nd t hat a dose-response relationship e xists.…”