Effects of prostaglandins on vesicourethral smooth muscle of rabbit therapeutic implications

The effects of PGF₂-alpha and PGE₂ on the vesicourethral smooth muscle of the rabbit were studied in vitro. PGF₂-alpha had potent contractile effects on the bladder body and comparatively less in the bladder base and the proximal urethra. PGE₂ contractile effects were two times greater than PGF₂-alpha on the bladder body but minimal or absent on the base and the urethra. The effects of PGF₂-alpha and PGE₂ seem to be mediated through a prostaglandin receptor as indicated by competitive antagonism of both prostaglandins by N-0164, a synthetic phenyl phosphonate. It also appears that the effects of PGF₂-alpha and PGE₂ may not be mediated through muscarinic, adrenergic, nicotinic, or histaminic receptors or direct smooth-muscle action. The therapeutic implications of PGE₂ in patients with problems of bladder emptying are discussed.