The role of the spleen in producing red blood cells during stress (measurements of haematocrit, haemoglobin, chloride, adrenaline conc., spleen mass) in Antarctic fish (Pagothenia borchgrevinki, Trematomus bernacchii)

The effects of stress (both hypoxia and exercise) on haematocrit in Antarctic fish was investigated with the aim to examine red cell release from the spleen under conditions of stress. The spleen of individuals of Pagothenia borchgrevinki was surgically isolated from the blood system to determine if it was acting as a supply of additional red cells during times of stress. Other fish had sham operations or no operations. Fish were designated as resting or exercised. The exercised fish were swum in a respirometer at a speed (~1.5 body lengths per second) known to produce a rapid increase in haematocrit. All fish were quickly killed and blood samples were collected from the caudal vein. Measurements were made of haematocrit (%) and haemoglobin concentration (mmol/L), and plasma was used for determinations of chloride and adrenaline concentrations (mmol/L). The spleen was removed from each animal and weighed (mass in grams and % body mass) and the haemoglobin concentration (mmol/L) was determined.