Cardiac remodelling, blood chemistry, haematology and oxygen consumption of Atlantic cod, Gadus morhua L., induced by experimental haemolytic anaemia with phenylhydrazine

Abstract

Anaemia is a common pathology associated with many infectious and non-infectious diseases. The effects of haemolytic anaemia induced by i.p. injection of phenylhydrazine (PHZ) were studied in Atlantic cod. Phenylhydrazine injection (0.3 mg kg(-1)) in a DMSO and saline vehicle induced a reproducible and stable anaemia reducing haematocrit, (Hct) by 62% over 3 weeks. Controls consisted of fish injected with saline and DMSO/saline vehicle with minimal effects on Hct or whole blood haemoglobin (Hb). Although anaemia resulted in reduced blood lactate and glucose in PHZ injected fish, there were no effects of anaemia on blood, sodium, chloride or potassium. Similarly, there were no changes in the relative proportions of leucocytes in the blood although an increase in the number of immature erythrocytes was observed in the anaemic fish. Anaemic fish showed a 29 and 22% increase in cardiac somatic index (CSI) relative to saline and vehicle controls, respectively, although there were no significant differences in the linear dimensions of the ventricle. Changes in cardiac somatic and ventricular somatic index correlated positively and significantly with Hct but not with whole blood Hb concentration. Anaemic fish had significantly reduced resting routine oxygen consumption compared with vehicle controls but were not able to increase oxygen consumption following a bout of exhaustive exercise. Plasma lactate concentrations increased significantly after exercise to a greater extent in anaemic fish compared with vehicle control fish. Phenylhydrazine is a useful model for studying haemolytic anaemia in Atlantic cod with minimal effects on blood biochemistry and haematology and clearly reduces the aerobic capacity in Atlantic cod.

Cardiorespiratory responses to haemolytic anaemia in rainbow trout Oncorhynchus mykiss

“…labrax (Wang et al , ), but contrasts with the reported decrease in for anaemic G . morhua (Powell et al , ) and O . mykiss (Gallaugher et al , ).…”

“…For example, routine has been reported to remain stable (Cameron & Davis, ) and to decrease significantly (Gallaugher et al , ) in anaemic rainbow trout Oncorhynchus mykiss (Walbaum, 1792). Likewise, routine was stable in anaemic pinfish Lagodon rhomboides (L. 1766) (Cameron & Wohlschlag, ), starry flounder Platichthys stellatus (Pallas 1787) (Wood et al , ) and European sea bass Dicentrarchus labrax (L. 1758) (Wang et al , ), but decreased significantly in anaemic Atlantic cod Gadus morhua L. 1758 (Powell et al , ). Also, while most anaemic fishes elevate heart rate ( f H ) to compensate (Cameron & Wohlschlag, ; Cameron & Davis, ; Holeton, 1971 a , b , 1972; Gallaugher et al , ; Wang et al , ), P .…”

Cardiac remodelling of Atlantic halibut Hippoglossus hippoglossus induced by experimental anaemia with phenylhydrazine

“…With either type of anaemia (haemorrhagic or haemolytic), the result is a reduction in the oxygen‐carrying capacity of the blood that stimulates erythropoietin transcription through hypoxia‐inducible factor 1 α (HIF‐1 α ). Increases in cardiac output occur, driven by increases in stroke volume and cardiac frequency and aided by cardiac hypertrophy resulting from structural remodelling of the heart at least in phenylhydrazine‐induced anaemia in rainbow trout, Oncorhynchus mykiss (Walbaum 1792), (Simonot & Farrell, 2007, 2009) and cod Gadus morhua L. 1758 (Powell et al , 2011). Bottom dwelling fishes such as pleuronectiformes have been observed with low haematocrits, although the mechanisms by which the fishes may compensate for these effects are unknown.…”

“…It does, however, suggest that a state of anaemia with haematocrit of 7·6% or 2·5 g dl −1 haemoglobin did not appear to relate directly to a chronic state of hypoxaemia in H. hippoglossus where an increase in circulating lactate might be expected. Wood et al (1982) also reported no increase in plasma lactate levels in anaemic P. stallatus nor have increases in plasma lactate been noted in other marine fishes suffering from phenylhydrazine‐induced anaemia (Burke, 2009; Powell et al , 2011). Blood lactate may not reflect cellular hypoxaemia or the relationship with haematocrit and haemoglobin concentration may not be direct or may be delayed.…”

“…The reasons for these species differences are not clear, although the difference in lifestyle of the fishes may offer some explanation. Hippoglossus hippoglossus , like G. morhua (Powell et al , 2011), are cold water species and demersal or demerso‐pelagic. Seriola lalandi on the other hand are very active pelagic species found in much warmer environments.…”