Response to alkyltins of two Na+-dependent ATPase activities in Tapes philippinarum and Mytilus galloprovincialis.
Organotin effects on the Na-dependent ATPases involved in ionic regulation of aquatic animals are poorly known, in spite of the largely documented contamination of seafood, especially bivalve molluscs. This study deals with the in vitro effect of TBT on the Na,K-ATPase and the ouabain-insensitive Na-ATPase in gill and mantle microsomes from the cultured bivalve molluscs Tapes philippinarum and Mytilus galloprovincialis. In the mussel also MBT, DBT and TeET were tested. While in both species the Na-ATPase showed an overall refractoriness to organotins, the Na,K-ATPase was progressively inhibited by increasing TBT concentrations (0-34 microM). In both species the Na,K-ATPase activity was more strongly inhibited in the gills than in the mantle. At the maximal TBT concentration tested (34.4 microM), while gill Na,K-ATPase activity was abolished, mantle enzyme activity was, respectively, reduced to 20% in T. philippinarum and to 50% in M. galloprovincialis. Mussel Na,K-ATPase was differently susceptive to the organotins tested and in both tissues showed an inhibition efficiency order TBT>DBT>>MBT=TeET (no effect), tentatively related to the different organotin polarity and to a possible interaction with membrane-bound enzyme complexes. The different response of the two ATPases to organotins is consistent with the known different susceptivity of the two enzyme activities to environmental contaminants, assay conditions and endogenous factors.
Department of Biochemistry G. Moruzzi, Section of Veterinary Biochemistry, University of Bologna, Via Tolara di sopra, 50, 40064 Ozzano Emilia (BO), Italy. apagliar@vet.unibo.it
Alessandra
A
Pagliarani
Patrizia
P
Bandiera
Vittoria
V
Ventrella
Fabiana
F
Trombetti
Maurizio
M
Pirini
Anna Rosa
AR
Borgatti
D000818:Animals; D049872:Bivalvia / Q000201:enzymology*; D004305:Dose-Response Relationship, Drug; D005880:Gills / Q000201:enzymology; D016014:Linear Models; D008861:Microsomes / Q000201:enzymology; D049878:Mytilus / Q000201:enzymology; D009947:Organotin Compounds / Q000008:administration & dosage / Q000378:metabolism / Q000633:toxicity*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013045:Species Specificity; D014220:Trialkyltin Compounds / Q000008:administration & dosage / Q000378:metabolism / Q000633:toxicity*
D009947:Organotin Compounds; D014220:Trialkyltin Compounds; C516409:mono-n-butyltin; C056189:di-n-butyltin; C032789:tetraethyltin; C011559:tributyltin; D000254:Sodium-Potassium-Exchanging ATPase