Low level lead inhibits the human brain cation pump.
The impact of low level lead exposure on human central nervous system function is a major public health concern. This study addresses the inhibition of the cation pump enzyme Na, K-ATPase by low level lead. Human brain tissue was obtained at autopsy and frozen until use. Brain homogenates were preincubated with PbCl2 for 20 min at 0 degrees C. Inhibition of K-paranitrophenylphosphatase (pNPPase), a measure of the dephosphorylation step of Na,K-ATPase, reached steady state within 10 min. K-pNPPase activity, expressed (mean +/- SEM) as a percentage of control (45.2 +/- 2.7 nmol/mg/min), fell to 96.3 +/- 0.9% at 0.25 uM [PbCl2] to 82.0 +/- 1.6% at 2.5 uM [PbCl2] in homogenates prepared from normal brain. Similar results were obtained with homogenates prepared from brains of patients with a history of alcohol abuse and of those with other miscellaneous conditions. Since the mean blood level of lead in the United States has ranged recently from 9.2 to 16.0 ug/dl (0.44 to 0.77 uM), these results indicate that current in vivo levels of lead exposure may impair important human brain function.
Bertoni
J M
JM
Department of Neurology, Creighton University, Omaha, NE 68131.
Sprenkle
P M
PM
D009597:4-Nitrophenylphosphatase / Q000037:antagonists & inhibitors; D000328:Adult; D000375:Aging / Q000378:metabolism; D000437:Alcoholism / Q000201:enzymology / Q000378:metabolism; D001693:Biological Transport, Active / Q000187:drug effects; D001921:Brain / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D006801:Humans; D007854:Lead / Q000494:pharmacology*; D008274:Magnesium; D008875:Middle Aged; D011188:Potassium; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*
D007854:Lead; C029891:lead chloride; D009597:4-Nitrophenylphosphatase; D000254:Sodium-Potassium-Exchanging ATPase; D008274:Magnesium; D011188:Potassium