Abstract
The effect of certain antibiotics on the ureteral tone and motility has been studied in vitro and in situ in guinea-pigs and dogs. Tetracycline and rolitetracycline induced a constriction, while ampicillin, isoxazolyl penicillins, gentamicin, aminosidin, spiramycin and chloramphenicol induced a relaxation of the ureter. In vivo, the responses were independent of both bladder activity and systemic effects related to the antibiotic flowing into the ureter and eventually absorbed from it. The antibiotics acted directly on the ureteral smooth muscle; factors influencing the action were: (a) the free or conjugated form of the antibiotic flowing through the ureter; (b) pH of the urine; (c) time of contact; (d) time lag.
