Respiratory Response to Experimentally Induced Anaemia in the Pinfish (Lagodon Rhomboides)

Abstract

Injection of phenylhydrazine hydrochloride produced surviving pinfish with as low as 0·26 g. % haemoglobin (2·9% of the normal value). Haematocrits dropped as low as 1–2%, against a normal value of about 30%. Measurements of resting metabolism showed no significant difference related to haemoglobin level, but anaemic fish were slightly higher. Tolerance times at low oxygen levels were not clearly related to haemoglobin levels. Cardiac rates show a compensatory increase in response to haemoglobin reduction which accounts for about 50% of the predicted increase in cardiac output. Haemoglobin is thought to provide a reserve capacity in circulatory ability for oxygen transport through its influence on cardiac output. The reserve capacity is important in meeting unusual demands of migration or escape, and may prove useful in comparing different species.