COMPARISON OF 3 HISTOLOGICAL FIXATIVES ON THE IMMUNOREACTIVITY OF MAMMALIAN P-GLYCOPROTEIN ANTIBODIES IN THE SHEEPSHEAD MINNOW, CYPRINODON-VARIEGATUS

Mammalian P-glycoprotein is a highly conserved integral membrane prote in functioning as an energy-dependent efflux pump which decreases the concentration of certain lipophilic aromatic compounds entering the ce ll by diffusion. Expression of such a transporter in teleost species c ould play a significant role in conferring resistance to fish populati ons exposed to xenobiotic stressors and may serve as a potential indic ator of species at risk for certain environmental contaminants. In pre vious studies we demonstrated that a strong correlation existed betwee n corresponding mammalian and teleost tissues showing immunoreactivity to specific mammalian P-glycoprotein antibodies. In the present study , comparisons of staining pattern, intensity, and tissue specificity b etween tissues treated in Bouin's, Dietrich's and Lillie's histologica l fixatives were determined in the sheepshead minnow, Cyprinodon varie gatus, using monoclonal antibodies C219, C494, JSB-1 and polyclonal an tiserum MDR(Ab-1). Immunoreactivity of these antibodies was found to b e fixative-dependent. Results are presented illustrating the different ial staining patterns and tissue specificity observed for each tissue type, fixative, and antibody combination. Our data indicate tissue fix ation has a significant impact on P-glycoprotein antibody immunoreacti vity in teleost tissues and must be considered in the comparison and i nterpretation of results. J. Exp. Zool. 281:251-259, 1998. (C) 1998 Wi ley-Liss, Inc.dagger.