Lead increases urinary zinc excretion in rats

Area of Science:

• Toxicology
• Environmental Health
• Nutritional Biochemistry

Background:

• Lead (Pb) is a toxic metal with known adverse health effects.
• The impact of lead exposure on essential mineral metabolism, specifically zinc (Zn), requires further investigation.

Purpose of the Study:

• To investigate the effect of acute and chronic lead (Pb) exposure on urinary zinc (Zn) excretion in rats.
• To determine if Pb exposure alters the excretion of other electrolytes like sodium (Na) and potassium (K).
• To assess the impact of chronic Pb exposure on tissue Zn content and plasma renin activity.

Main Methods:

• Acute exposure: Rats received intravenous injections of varying Pb doses (0-3 mg/kg), with urinary electrolyte excretion monitored for 6 hours.
• Chronic exposure: Rats were administered Pb (500 ppm) or a control solution in drinking water for 9 weeks, with daily monitoring of Zn excretion.
• Tissue analysis: Zn content in plasma, kidneys, and testes was measured at sacrifice (70 days). Plasma renin activity was also assessed.

Main Results:

• Acute Pb exposure at the highest dose (3 mg/kg) significantly increased urinary Zn excretion, with no effect on Na or K excretion.
• Chronic Pb exposure led to elevated urinary Zn excretion from day 2 to day 35 post-treatment.
• Pb-exposed rats showed decreased Zn content in plasma and testes, but not kidneys, and exhibited higher plasma renin activity.

Conclusions:

• Chronic lead exposure in rats increases urinary zinc losses.
• These increased urinary losses contribute to a reduction in tissue zinc levels, particularly in plasma and testes.
• Elevated plasma renin activity is associated with chronic lead exposure in rats.