The effect of diagnostic radiopaque fluids used in discography on chymopapain activity

It has been thought that intradiscal injection of radioopaque fluids prior to intradiscal chymopapain therapy might have some inhibitory effect on its enzyme activity and, thus, disc nuclear dissolution. This raised the question--what interval should elapse between discography and injection of the chymopapain to avoid this possible effect? The effects of Hypaque (Conray), metrizamide, and Urografin on chymopapain activity were measured. The most suitable substrate was N. Benzoyl-DL-arginine paranitroanilide (BAPNA). The yellow p-nitro aniline liberated (a measure of the enzymic activity of chymopapain) was determined by absorption spectrometry. Controlled series using 1) Hypaque plus substrate plus no enzyme, 2) Hypaque, enzyme, no substrate, and 3) Hypaque plus substrate plus enzyme showed no action. Hypaque (Conray) and Urografin are seen to enhance enzymic action of chymopapain. Metrizamide has slight inhibitory action. Effects of Dimerex were variable. Weak Hypaque increases activity (20%); 100% solution doubles activity. Thus, there is no necessity to delay injection of enzyme after Hypaque, Conray, Urografin, especially as disc radioopacity can persist up to 24 hours. Prior injection of 95% alcohol (as used by Trosier) abolishes chymopapain activity.