Effect of a radiographic contrast agent on renal function in the rat. Comparison with equiosmolar mannitol

The renal effects of the radiographic contrast agent meglumine iothalamate (Conray; C) were evaluated in rats. C produced a 42% fall in glomerular filtration rate (p less than 0.05) and a 44% fall in effective renal plasma flow (p less than 0.05). The effects of C were blunted by both acute and chronic volume expansion. Equiosmolar mannitol produced similar hemodynamic responses as C. The fractional excretions of sodium and potassium were similar in rats given C or mannitol. The renal effects of C appear to be due to its hypertonicity. These effects may be modified by volume expansion.