Role of intracellular calcium stores in contrast medium-induced renal vasoconstriction.
OBJECTIVE
Renovascular smooth muscle contractility, an important factor in contrast media-induced nephrotoxicity, depends on intracellular Ca2+ concentration, which is composed of extracellular Ca2+ influx and intracellular Ca2+ release. These factors were investigated in contrast media-induced renal vasoconstriction in an in vitro model.


METHODS
KCl-induced isometric contractions of rabbit renal artery were compared with contractions elicited by contrast media (diatrizoate, iohexol, iopamidol). Measurements were made after incubation with the Ca2+ channel blockers nifedipine, verapamil, and diltiazem to assess the role of extracellular Ca2+ influx and after ryanodine and thapsigargin to investigate the role of intracellular Ca2+ release.


RESULTS
The Ca2+ channel blockers partially inhibited contractions induced by contrast media, while KCl-induced contractions were completely abolished. Ryanodine and thapsigargin also markedly inhibited contrast media-induced contractions.


CONCLUSIONS
Ionic and nonionic contrast media induced quantitatively different renal vasocontractions. Ca2+ channel blockers inhibited this vasocontraction only slightly compared with intracellular Ca2+ release blockers.
Drescher
P
P
Department of Radiology, Medical College of Wisconsin, Milwaukee 53226, USA.
Rauch
D
D
Madsen
P O
PO
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D003287:Contrast Media / Q000633:toxicity*; D009994:Osmolar Concentration; D011189:Potassium Chloride / Q000494:pharmacology; D011817:Rabbits; D012077:Renal Artery / Q000187:drug effects*; D012433:Ryanodine / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects*
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D003287:Contrast Media; D012433:Ryanodine; D011189:Potassium Chloride; D019284:Thapsigargin; D002118:Calcium