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.