ADVERSE-EFFECTS OF POLLUTED CONTINENTAL WATER BODIES IN CHILE ON FROGADRENERGIC SYNAPSE

For many years health risks from chemical exposures have been examined by several programmes within the World Health Organization (Becking, 1992), including analysis of drinking waters derived from river basins exposed to industrial wastes. There is growing interest in an approac h that evaluates susceptibility of the organism to pollutants by the u se of biomarkers which may indicate the presence of contaminants in ce lls (McCarthy and Shugart, 1990; Winneke and Lilienthal, 1992). One of these markers is the isolated toad skin, which has been used extensiv ely as a biological model to investigate the cellular effects of numer ous drugs (Alarcon, 1995) which alter ion transport across the epithel ium. Neurotoxic effects have occurred when chemicals interfere with ne rve transmission because they enter the environment through the proces s of industrialization and pollution (Tilson, 1993). The adrenergic sy napse between sympathetic nerve endings and skin mucous glands is a bi omarker which has been studied by authors (Norris and Quevedo, 1993a) who showed that the response to nerve stimulation consisted of a rise in the potential difference (PD) and in the short-circuit current (SCC ) across the skin. This response is due to an increase in active Cl- t ransport by the mucous glands (Thompson and Mills, 1981). Effluents fr om cellulose and paper plants contain a mixture of chemical reagents u sed in digestion of wood, cellulose fibres and lignin, and of other ch emical compounds including organochlorines derived from the bleaching process (Badinella, 1993). Several wood pulp and paper industries disc harge their wastes into the Bio-Bio, a Chilean river 380 Km in length (VIIIth Region, 37.5 degrees Lat., 73.5 degrees Long.) causing polluti on which affects urban centres and rural surroundings, and their effec ts on some biomarkers (Venegas et al.,1993) have been investigated. Ho wever, there are no studies on the neurotoxic effects of pollutants re leased in these effluents. The aim of the present work is to examine t he action of potentially toxic industrial wastes taken from different sources, on a) the responses of the frog nerve-skin preparation to ele ctrical stimulation; b) the bioelectric parameters (PD and SCC) of the isolated toad skin; and c) the characteristics of frog sciatic nerve compound action potential. A map of the location of the Bio-Bio river showing the sample sites is included (Fig. 1).