Background
Mercury's deleterious effects are associated with increased cardiovascular
risk.
Objective
To determine whether chronic exposure to inorganic mercury increases the
activity of angiotensin-converting enzyme and its relationship with
oxidative stress in several organs and tissues.
Methods
We studied male Wistar and spontaneously hypertensive rats (SHR)
(3-month-old) exposed or not to HgCl
2
for 30 days. At the end of
treatment, we investigated the following: changes in body weight,
hemodynamic parameters, angiotensin-converting enzyme (ACE) activity and
oxidative stress in the heart, aorta, lung, brain and kidney in hypertensive
compared to normotensive animals. A value of p < 0.05 was considered
significant.
Results
Chronic exposure to HgCl
2
did not affect weight gain in either
group. Systolic blood pressure, measured weekly, did not increase in Wistar
rats but showed a small increase in SHR rats. We also observed increases in
left ventricular end-diastolic pressure and ACE activity in the plasma and
hearts of normotensive rats. In the SHR+Hg group, ACE activity increased in
plasma but decreased in kidney, lung, heart, brain and aorta. Oxidative
stress was assessed indirectly by malondialdehyde (MDA) production, which
increased in Hg-treated rats in both plasma and heart. In the SHR+Hg group,
MDA increased in heart and aorta and decreased in lungs and brain.
Conclusion
These results suggest that chronic exposure to inorganic mercury aggravates
hypertension and produces more expressive changes in ACE activity and
oxidative stress in SHRs. Such exposure affects the cardiovascular system,
representing a risk factor for the development of cardiovascular disorders
in normotensive rats and worsening of pre-existing risks for
hypertension.
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