|
|
EMBARGOED
FOR RELEASE UNTIL
October 8, 2007
APS Contact
Donna Krupa
Office:
(301) 634-7253
dkrupa@the-aps.org
www.The-APS.org
Lead Exposure Accelerates
Chronic Kidney Disease
Lead
raises blood pressure and injures kidney tissue, accelerating chronic
disease in an experimental model
(Bethesda, MD) – As Americans grow more
concerned about lead levels found in children’s’ toys, a new study finds
that lead exposure accelerates chronic renal disease by raising blood
pressure and accelerating injury to kidney tissues and blood vessels. The
findings are published in the online edition of the American Journal of
Physiology–Renal Physiology.
Lead exposure has long been associated with high blood
pressure (hypertension), arteriolosclerosis, kidney disease and gout.
Studies in workers exposed to lead have confirmed these associations. Other
studies have suggested that even low levels of lead in the blood can be
associated with higher frequencies of high blood pressure and chronic kidney
disease.
The new study, the first of its kind in an animal
model, shows that low level lead exposure accelerates chronic renal disease,
primarily by raising blood pressure and accelerating certain kinds of
cellular injury. It was conducted by Carlos Roncal, Wei Mu, Sirirat Reungjui,
Kyung Mee Kim, George N. Henderson, Xiaosen Ouyang, Takahiko Nakagawa, and
Richard J. Johnson, all of the Division of Nephrology, Hypertension, and
Transplantation, University of Florida, Gainesville, FL. The study is
entitled, “Lead, at Low Levels, Accelerates Arteriolopathy and
Tubulointerstitial Injury in Chronic Kidney Disease”. It appears in the
online edition of the American Journal of Physiology-Renal Physiology.
Study of Chronic, Low Dose Lead Exposure
The study used male rats which were fed a standard
diet. In addition, 16 of the rats consumed drinking water treated with lead
acetate (i.e., 150 ppm of lead (L)) for four weeks. The dose of lead
administered resulted in mild toxicity and is similar or slightly lower than
the levels observed in subjects with occupational exposure. Thereafter they
underwent remnant kidney (RK) surgery and afterwards continued on the lead
acetate for 12 more weeks.
A control group also underwent RK surgery but without
lead acetate. At eight and 12 weeks after surgery, the body weight of all
the rodents was measured and systolic blood pressure was assessed. Twelve
weeks after RK surgery, kidney tissue was collected for histologic and
molecular biologic studies from both groups.
Study Results
Lead treatment was well tolerated and resulted in
modest elevations in whole blood lead levels (26.4 ± 4.5 vs. 1 0 µg/dl, wk
16, p ± < 0.001). But low lead
level exposure reduced body weight, increased blood pressure and worsened
renal dysfunction. Specifically, lead exposure:
-
was associated with higher systolic blood pressure and
worse renal function (creatinine clearance 1.4±0.4 vs. 1.8 ±0.5 ml/min,
RK+L vs. RK, p<0.05), and with a tendency for greater urinary protein
(6.6±6.1 vs. 3.6±1.5 mg protein/mg creatinine, RK+L vs. RK); and
-
while scarring in the renal capillary system tended to be
worse in lead treated rats (37.6 ± 11 vs. 28.8 ± 2.3 percent, RK+L vs.
RK), the most striking finding was that kidney tissue disease
(arteriolar disease, peritubular capillary loss, tubulointerstitial
damage and macrophage infiltration) worsened with lead exposure. These
developments were associated with the significantly
increased renal expression of monocyte chemoattractant protein-1 mRNA.
Conclusions
According to Dr. Johnson, the seior researcher, “This
study examined the effect of mild, chronic lead intoxication in an
experimental model of chronic renal disease. The dose of lead administered
resulted in mild toxicity. This degree of lead poisoning was sufficient to
cause higher blood pressures and accelerate the progression of renal
failure.”
###
Journal Publication Information
Online edition of the American Journal of Physiology—Renal Physiology
For Members of the Press
For a copy of the paper, or to arrange an interview with the lead
researcher, please contact Donna Krupa at 301.634.7209 (direct dial), or
dkrupa@The-APS.org.
Key Words
Lead exposure and high blood pressure; lead exposure and kidney disease
Physiology is the study of how molecules, cells, tissues and organs function
to create health or disease. The American Physiological Society (APS) has
been an integral part of this scientific discovery process since it was
established in 1887.
|
|
