engleski

A new type of hazardous chemicals: The chemosensitizers of multixenobiotic resistance

The purpose of this overview is to introduce the property of a new class of hazardous chemicals -- the inhibitors of multixenobiotic resistance (MXR) in aquatic organisms, referred to as chemosensitizers. In fact, novel is the discovery that aquatic organisms possess MXR, a mechanism similar to the well known P-glycoprotein extrusion pump in multidrug resistant (MDR) tumor cells. MXR in aquatic organism removes out of cells and organisms both endogenous and environmental xenobiotics, including also some man-made chemicals. MXR in aquatic organisms represents a general biological first-line defence mechanism for protection against environmental toxins. Many chemical agents, the chemosensitizers, may alter the function of this fragile mechanism. It is this new, MXR-inhibiting, property, unrecognized as yet, that classifies these chemicals among top-rank hazardous water pollutants. The knowledge that the presence of one xenobiotic may block the pumping out of other xenobiotic(s), and hence accelerate their accumulation, may have important implications on environmental parameters like exposure, uptake, bioaccumulation, and toxicity. In this overview we present (1) the evidence for the expression of MXR-phenotype in aquatic organisms, (2) the demonstration of toxic consequences caused by MXR-inhibitors, and (3) the description of methods for measurement of concentration of MXR-inhibitors in environmnetal samples, or for measurement of MXR-inhibiting potential of chemicals.

aquatic organisms; chemosensitizers; determination of; induction; inhibition; multixenobiotic resistance; P170 glycoprotein

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