Cardiovascular changes and physiological response during nitrite exposure in rainbow trout

Abstract

Nitrite-exposed (1 m) rainbow trout Oncorhynchus mykiss fell into two distinct groups with regard to susceptibility and physiological response. Group 1 accumulated nitrite in plasma to a concentration of 2·9 m within 24 h and died before 48 h. Group 2 survived for 96-144 h, and the accumulation of nitrite was slower, levelling off at a concentration c. 2·3 m at 72 h. Methaemoglobin (metHb) formation was faster in group 1 than in group 2, but both groups had a metHb fraction c. 70% before dying. The extracellular electrolyte balance was perturbed significantly only in group 1, where plasma [Cl ] decreased and plasma [K + ] increased. Heart rate increased rapidly, more in group 1 than in group 2. The tachycardia occurred before any significant changes in metHb or [K + ] had developed, suggesting that it was due to nitriteinduced vasodilation, possibly via nitric oxide generated from nitrite, that was countered by an increased cardiac pumping to re-establish blood pressure. Arterial blood pressure and pulse pressure were accordingly kept reasonably constant. Heart rate variability was significantly depressed in group 1. The ventilation rate was significantly increased fter 9 h of nitrite exposure in group 1, while the ventilation in group 2 did not increase significantly before 21 h. The data reveal that nitrite has substantial influence on the cardio-respiratory function in fishes. 2001 The Fisheries Society of the British Isles

Passage efficiency of offset and straight orifices for upstream movements of Iberian barbel in a pool‐type fishway

“…Similarly, no gasping behaviour or tissues damages signs (e.g. gill damage), which are frequently seen in nitrite‐intoxicated fish (Lewis and Morris, 1986; Jensen et al ., 1987; Aggergaard and Jensen, 2001) were observed. Indeed, pH, temperature and concentration of dissolved oxygen levels in water; which are key factors in the nitrifications process and in the consequent auto‐oxidation of haemoglobin due nitrite accumulation (i.e.…”

Nitrite-induced methemoglobinemia in Nile tilapia, Oreochromis niloticus

“…Earlier reports on the parallels between nitrite and methemoglobin are contradictory. It has been reported that the percentage of methemoglobin is closely correlated to the concentration of nitrite in blood and water (Palachek and Tomasso, 1984; Aggergaard and Jensen, 2001). After acute exposure to nitrite, elevated methemoglobin levels were also observed by Klinger (1957) in European minnow ( Phoxinus phoxinus ), by Westin (1974) in chinook salmon ( Oncorhynchus tshawytscha ) and by Svobodova et al.…”

Toxic effects of nitrite on freshwater organisms: a review

“…; Knudsen & Jensen ; Gisbert et al . ), respiratory processes (Cameron ; Aggergaard & Jensen ), cardiovascular functions (Aggergaard & Jensen ), and endocrine and excretory processes (Jensen ). Details can be found in comprehensive review by Jensen () which is still up to date.…”

“…Important internal factors include the fish species, age, size and individual fish sensitivity (Eddy et al . ; Palachek & Tomasso ; Williams & Eddy ; Bartlett & Neumann ; Aggergaard & Jensen ). The importance of the separate factors is subject to continuous verification and correction.…”