ISSN:
1432-1793
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The distribution of metals (Ba, Cr, Cu, Fe, Mn, Ni and Zn) in the blood plasma and the circulating hemocytes was determined for a eulamellibranch bivalve, the quahog Mercenaria mercenaria (L.), collected from a relatively clean site at Falmouth, Massachusetts, USA. Whole blood volume was an exponential function of quahog length (Y=5.71×10-5 X3.0678; Y=ml of whole blood; X=mm length). Of this volume, 1.2±0.3% ( $$(\bar X \pm {\rm{SD)}}$$ ) was attributable to blood cells. Total metal content (μg metal, or μg metal normalized per g of whole blood) was much higher in blood plasma than in hemocytes. In quahogs exposed in the laboratory to 100 ppb 109Cd, 93.0% of the total accumulated blood Cd was in the plasma rather than in the circulating hemocytes (7.0%), irrespective of the length of exposure (1 h to 31 d). Less than 5% of the plasma Cd was either Cd2+, small inorganic Cd complexes or bound to organic molecules with a molecular weight smaller than 1 000. Cadmium was primarily bound to high molecular weight protein(s) (〉60 000 daltons) within the plasma. This plasma protein-Cd complex has a low affinity constant (approximately 104 M -1), indicating non-specific Cd binding, although the capacity for Cd-binding in the plasma is great (as high as 200 μg Cd per ml of plasma). Blood plasma may be far more important in metal transport than has previously been realized.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00391250
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