Circulatory effects of acute or chronic endotoxemia in rats

A study was made of the effects of acute (4 h) infusion of Escherichia coli endotoxin on cardiovascular function in rats. Rats with acute endotoxemia had a reduced cardiac output but maintained their arterial blood pressure. Fractional distribution of the cardiac output was increased to the liver and reduced to the gastorintestinal tract and skin. No changes in fractional distribution to the kidneys, lungs, or heart were observed although absolute blood flow to these areas was reduced. Rats with chronic endotoxemia had a reduced cardiac output and hypotension with no change in peripheral resistance. Other changes resembled those seen in acute endotoxemia apart from a low renal fraction of the cardiac output. Calculation and interpretation of blood flow changes in these animals was difficult because of a large fall in hematocrit and changes in organ weight.