MERCURY SUPPRESSION OF A POTASSIUM CURRENT IN HUMAN B-LYMPHOCYTES

Mercury is a recognized environmental toxin. Several organ systems are targeted by this substance and impairment of immune function is known to result from exposure to mercury. Using the patch clamp technique i n the whole cell configuration on resting human B lymphocytes we have identified an outward potassium current and studied the effects of mer cury on this current. We present data that demonstrate: (i) the absenc e of inward currents; (ii) a time and voltage dependent outward curren t with a threshold of -40 mV and reversal potential near E(K+); (iii) blocking of this current by TEA (tetraethylammonium chloride) in a dos e dependent manner; (iv) a slow time course for recovery from inactiva tion of this outwardly rectifying K+ current and, (v) the diminution a nd final block of this potassium current by mercury. These data supple ment the findings from our laboratories that demonstrate inhibitory ef fects on B cell activation by mercury. We propose that the movement of potassium ions across the B cell membrane, an event presumed to be on e of the first signals in the mitogenic process, is a target of mercur y toxicity.