DRUG EFFECTS ON CEREBRAL BLOOD-FLOW IN THE BABOON MODEL - ACETAZOLAMIDE AND NIMODIPINE

The sensitivity of the baboon model under anaesthesia for single photo n emission computed tomography (SPECT) of the brain with Tc-99m-HMPAO, as recently developed by us to study cerebral blood flow patterns, wa s investigated using drugs that are known to increase cerebral blood f low, e.g. acetazolamide, the carbonic anhydrase inhibitor and nimodipi ne, the calcium channel blocker. Increases in cerebral blood flow for both acetazolamide and nimodipine were observed that correspond well w ith other studies. Statistically significant regional specificity was noted for acetazolamide and nimodipine. Interestingly a combination of these drugs did not enhance cerebral blood flow but rather decreased it in comparison with the individual drug responses. The results were correlated with arterial blood pressure, heart rate, pCO(2) and pO(2). A blood pressure decrease was noted for both drugs, while acetazolami de had a marked influence on pO(2). The results indicate that the babo on model is sensitive for evaluation of drug effects on cerebral blood flow.