Endotoxin does not directly alter norepinephrine release or vasoactivity in dog pulmonary artery and portal vein

The direct effect of Escherichia coli endotoxin on the release of norepinephrine (NE) and the contractile response consequent to the release of NE were studied in isolated, superfused segments of dog pulmonary artery and portal vein during resting conditions and during electrical stimulation (ES). High-pressure liquid chromatography with electrochemical detection was used to quantify the endogenous NE released and that remaining in the tissue after stimulation. Endotoxin (1 micrograms/ml and 10 micrograms/ml in superfusate) had no effect on the release of NE from either pulmonary artery or portal vein. Endotoxin also had no effect on vasoactivity in response to ES. Thus, in isolated pulmonary artery and portal vein, endotoxin, in the doses employed, does not directly affect release of NE from adrenergic nerve endings, nor does it affect the sequence of events that starts with transmitter-receptor interaction and ends with contraction of smooth muscle cells.