The ureter in vitro: normal motility and response to urinary pathogens.

The effects of bacteria on in vitro ureteric contractility were studied, using a model which allowed selective exposure of organisms to the ureteric mucosa and smooth muscle, respectively. A cannula attached to a pressure transducer was ligated into the proximal lumen of 2.5-cm segments of canine ureter. The distal ureter was ligated to form a closed pressure monitored system, and the segment suspended in a 20-ml organ bath containing Krebs Henseleit buffer at physiological pH and temperature. Following onset of spontaneous activity, broths of Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa and Staphylococcus aureus were added to either the buffer solution or ureteric lumen in doses of > 10(6) organisms/ml. Experiments were repeated using heat-killed organisms, bacterial filtrates and E. coli endotoxin. Ureteric contractility was stimulated by organisms added to the buffer medium, but reversibly inhibited by bacteria placed in the ureteric lumen. Heat-killed organisms, endotoxin and live filtrates had no effect on normal motility when exposed to either the ureteric mucosa or muscularis respectively. These findings reflect the conflicting changes in ureteric motility seen in vivo when bacteria are administered systemically or directly into the ureteric lumen.