RATIONALE AND OBJECTIVES. Changes in contractility of corpus cavernosu
m (CC) smooth muscle caused by radio contrast medium may result in mis
interpretations of cavernosography used diagnostically in erectile dys
function. METHODS. The authors investigated the direct effect of vario
us contrast media on rabbit CC smooth muscle tissue strips in a in vit
ro model by adding contrast medium to the tissue in a perfusion bath a
nd recording the resulting contractions. Glucose addition was used as
control. RESULTS. Application of high-osmolar, ionic contrast medium d
iatrizoate-induced CC smooth muscle contractions of 57% of the control
potassium chloride (124 mM) induced contractions. The low-osmolar (86
2 mOsm/kg) nonionic monomer contrast medium, iohexol, and the iso-osmo
lar (300 mOsm/kg) nonionic dimer contrast medium, iodixanol, elicited
contractions of 34% and 36% of the potassium chloride control contract
ions, respectively. High- and iso-osmolar glucose solutions caused con
tractions of 51%, 38%, and 24% of the control, respectively. Cyclic ad
enosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP)
regulate CC smooth muscle contractions. These are influenced by diffe
rent drugs including phosphodiesterases (PDEs), forskolin, and 3-morph
olinsydnonimine hydrochloride (SIN-1). The nonspecific PDE inhibitors
papaverine (0.1 mM) and theophylline (1 mM) reduced the contrast mediu
m-induced contractions to 66% and 69%, respectively. The specific PDE
inhibitor milrinone (0.1 mM) reduced the contractions to 69%; 0.1 mM f
orskolin and SIN-1 reduced the contractions to 34% and 41%, respective
ly. CONCLUSIONS. Contrast medium induces CC smooth muscle contractions
, depending mainly on the osmolality of the solution. The contractions
are reduced but not abolished by elevating the intracellular cAMP and
cGMP concentrations. The clinical applications in cavernosography are
discussed.