Cadmium influx across isolated Carcinus gill epithelium interaction of lanthanum and calcium with cadmium influxes

The effects of Ca and La on Cd transport across apical and basolateral gill surfaces were examined in isolated perfused Carcinus gills. In the gills exposed to diluted sea water enriched with calcium by addition of CaCl sub(2) to 11.9 and 15.9 mmol/l the Cd influxes decreased by 55% and 85%, respectively, compared to those observed in diluted sea water (6.9 mmol Ca/l). When Ca was added to the perfusate to increase its concentration at the basolaterally oriented gill surfaces, Cd influx inhibition was less pronounced than when Ca was added apically. The effect of Ca on super(109)Cd influxes appears, therefore, to be exerted at the apical gill surface. Additionally, the effects of various concentrations of the non-specific Ca channel blocker La (added to diluted sea water) on super(109)Cd refluxes in isolated perfused Carcinus gills were studied. super(109)Cd influxes are shown to be lanthanum concentration dependent. The half-maximum inhibition of cadmium influxes by La occurred at 1.4 x 10 super(-6) mol/l. Cadmium transport is discussed in terms of non-specific influx utilizing Ca channels.