Pathogenesis of sodium selenite and dimethylselenide acute toxicosis in pigs: cardiovascular changes.

In pigs and other food producing animals, relatively little is known about the mode of action of excess selenium. This study reports the cardiovascular effects brought about in anaesthetised Landrace pigs by 2 mg selenium kg-1 bodyweight intravenously as either sodium selenite or dimethylselenide. Sodium selenite dosing was characterised by a dramatic fall in systemic blood pressure with an increase in cardiac output and heart frequency. The only significant change elicited by dimethylselenide was a linear rise of cardiac output. Neither of the tested compounds significantly affected pulmonary arterial pressure. These results suggest that under the experimental conditions in this study, sodium selenite induces a vasculogenic shock without primarily affecting cardiac performance. The lack of detrimental effects on cardiovascular parameters with dimethylselenide indicates the importance of methylation in detoxifying excess selenium.