The effect of subarachnoid metrizamide and iohexol on cerebral glucose metabolism in vivo.

We studied the effect of metrizamide and iohexol on local cerebral glucose utilization (LCGU) using autoradiography. Metrizamide or iohexol was introduced into the subarachnoid space of rabbits and positioned over the right hemisphere for 3 or 6 hours. Using the unexposed (left) hemisphere as an internal control, we calculated relative changes in LCGU. In the three metrizamide-exposed animals the LCGU was decreased over the contrast media-exposed right temporoparietal cortex (L-R difference was positive). There was no significant changes in LCGU and no positive L-R difference after treatment with iohexol (three animals). We conclude that metrizamide does affect glucose metabolism in vivo, and this effect is dependent on localization of the contrast medium. The clinically safer drug, iohexol, in similar concentration and higher osmolality, did not decrease glucose metabolism.