Figure 1. Effects of different doses of radiographic contrast medium on renal function of rats pre-treated with indomethacin and L-nitroarginine methyl ester (L-NAME). (a) Serum creatinine (Cr) before () and 24 h after () injection of 8 ml kg^-1 saline (Group 1, control) or increasing doses of diatrizoate (Group 2, 4 ml kg^-1; Group 3, 6 ml kg^-1; and Group 4, 8 ml kg^-1). Significant increases (^*p<0.01) in serum Cr occurred in Groups 3 and 4, but no significant rise occurred in Groups 1 and 2 (n=5 per group). The rise in serum Cr in Group 4 was significantly higher (p<0.05) than in Group 3. (b) Percentage change in Cr clearance from baseline (24 h pre injection) to 24 h post injection with 8 ml kg^-1 saline (Group 1, control) or increasing doses of diatrizoate (Group 2, 4 ml kg^-1; Group 3, 6 ml kg^-1; and Group 4, 8 ml kg^-1. Significant decreases (^*p<0.01) in Cr clearance occurred in Groups 3 and 4 but no significant change occurred in Groups 1 and 2 (n=5 per group). The decrease in Cr clearance in Group 4 was larger (p<0.05) than in Group 3.