α-Adrenergic antagonist inhibition of bacterial uptake of NE. Washed exponential cultures of E. coli O157:H7, S. enterica, or Y. enterocolitica were added at a cell density of around 2 × 108 CFU/ml to DMEM containing 50 μM NE plus 5 × 105 cpm/ml of 3H-NE and the following: no additions (Control), or 200 μM phentolamine, phenoxybenzamine or prazosin. Cultures were incubated statically for 6 hrs at 37°C in a 5% CO2 humidified incubator, and analysed for growth and 3H-NE uptake as described in Materials and Methods. 3H-NE uptake assays were performed in duplicate on at least two occasions; variation within individual assay sets was 5% or less, and between experiments no more than 10%. Antagonist supplemented cultures showed statistically significant decreases in uptake of 3H-NE (P < 0.001) as compared with the Control.