Effect of experimental lead toxicity on cardiovascular function in calves.

The effect of lead was studied on cardiovascular function in calves given oral doses of 5 mg lead acetate/kg body weight daily till the appearance of clinical signs of toxicity. Arterial blood pressure and electrocardiogram were recorded before (day 0) and on days 30 and 60 of lead administration. There was a significant increase in arterial blood pressure in lead-intoxicated calves on day 30 (124.8 +/- 1.0 mm Hg) with the peak values noted on day 60 (150.8 +/- 4.3 mm Hg). ECG in lead 11 showed marked increases in P wave duration and amplitude and duration of P-R interval. Duration of Q-T interval was decreased and T wave was inverted after 30 days of continuous lead exposure. Histopathological examination showed degeneration of cardiac musculature, mononuclear cell infiltration and swelling of Purkinjee fibers in calves sacrificed after the onset of irreversible signs of lead toxicity.