| Abstract: | The relation between the inhibitory action of prostaglandin E1 (PGE1) and external Ca concentration was investigated using the guinea-pig isolated ureter and the perfused central artery of the rabbit isolated ear. PGE1 20 ng/ml reduced the ureteral contraction evoked by a single electrical stimulation. This inhibitory action of PGE1 was enhanced with a decreased external Ca concentration. PGE1 100 ng/ml also reduced Ca-induced contracture of the ureter depolarized in Ca-free K(80 mM)-Krebs' solution. Furthermore, PGE1 50 ng/ml inhibited the responses of peripheral vascular resistance to noradrenaline, and this effect increased with a reduced external Ca concentration. |
