Effects of cadmium on anoxic survival, haematology, erythrocytic volume regulation and haemoglobin-oxygen affinity in the marine bivalve Scapharca inaequivalvis

Abstract

Exposure to 50 ppb Cd for 6 wk reduced survival of Scapharca inaequivalvis in anoxic water (LT 50 decreasing from ≈ 15 to 12 days). The treatment decreased packed erythrocyte volume (haematocrit) and erythrocyte count but increased mean cellular haemoglobin concentration. In vitro Cd administration had no significant effect on O 2 affinity or co-operativity in O 2 binding of the stripped haemolysate. Erythrocyte suspensions exhibited a slight volume regulatory decrease, following swelling in hypotonie media, and no significant capacity for volume regulatory increase under hypertonic stress. Neither pattern was markedly affected by in vivo or in vitro Cd administration, which however, tended to reduce the primary volume changes. The results are discussed as regards Cd toxicity and the cellular and molecular mechanisms implicated in volume regulation and tissue-O 2 supply.