THE EFFECT OF NIFEDIPINE AND VERAPAMIL ON RHYTHMIC CONTRACTIONS OF HUMAN ISOLATED URETER

The effect of calcium antagonists nifedipine and verapamil on spontane ous rhythmic contractions of human isolated ureter obtained from donor subjects undergoing kidney transplantation was investigated in compar ison with a nonsteroidal antiinflammatory drug indomethacin. Stop-time s i.e. the time elapsing from application, were determined for each dr ug. The rank order of potency at 10(-8) and 10(-7) M concentrations of the drugs was : nifedipine>verapamil greater-than-or-equal-to indomet hacin. However, no significant difference of the stop-times was observ ed at 10(-6) M concentration of the drugs tested. The rhythmic contrac tions were re-activated by PGF2alpha after stoppage with indomethacin but not with nifedipine or verapamil. These results suggest that not o nly endogenous PG synthesis but also an influx of calcium from the ext racellular space is responsible for the spontaneous rhythmic activity of human ureter. The beneficial effects of using calcium antagonists i n the treatment of ureteric colic is discussed.