B. Kurelec et al., DETERMINATION OF POLLUTANTS WITH MULTIXENOBIOTIC RESISTANCE INHIBITING PROPERTIES, Marine environmental research, 39(1-4), 1995, pp. 261-265
Recent evidence indicates that inherent presence of multixenobiotic re
sistance (MXR) mechanism represents a general biological defence mecha
nism for protection of organisms against both endogenous and environme
ntal toxins. In aquatic organisms exposed to polluted waters, this P-1
70 glycoprotein pump also removes 'new' man-made toxic chemicals out o
f cells. Many chemical agents may alter the function of this fragile m
echanism. A new class of compounds, referred to as 'chemosensitizers',
deserve a top rank among environmentally-hazardous chemicals, since t
hey block this basic natural defence mechanism. The authors measured t
he concentration of such MXR-inhibiting substances by two methods: the
'binding' assay and the 'efflux' assay. The 'efflux' assay of water f
rom the polluted Sava and Rhein Rivers and the unpolluted Korana River
revealed the presence of 440, 489, and 176 ppb of verapamil equivalen
ts of MXR-inhibitors, respectively. These concentrations of MXR-inhibi
tors obviously may revert the natural resistance of organisms inhabiti
ng these rivers to a pathobiologic sensitivity.