CADMIUM TRANSPORT IN SUBMERGED MACROPHYTE CERATOPHYLLUM-DEMERSUM L IN PRESENCE OF VARIOUS METABOLIC-INHIBITORS AND CALCIUM-CHANNEL BLOCKERS

Transport of Cd2+ in Ceratophyllum demersum was light dependent process requiring metabolic energy. The extent of Cd influx was linear up to 10 mu M external Cd2+ however, beyond that plateau after 120 min. Cadmium influx was more in the light than in the dark. Various uncouplers: 2,4-dinitrophenol (DNP), carbonyl cyanide m-chlorophenylhydrazone (CCCP), and ATPase inhibitor N-N-dicyclohexylcarbomidide (DCCD) limited this process, Cadmium ion and Ca2+ were antagonistically decreasing uptake of Ca2+ each other, Cd2+ influx followed Michaelis-Menten (Cd2+) saturation kinetics with a low value of Km 40.0 mu M which increased in the presence of Ca2+(66.66 mu M). Verapamil and nifedipine, blockers of voltage depenbenr 2+ uptake in the plant, however, provoked Cd2+ augmentation in both continuous and short Cd2+ exposure experiments, Highly significant Cd2+ influx provoked by verapamil and nifedipine was possibly due to enhanced diffusion of Cd2+ in the dark.