ACETAZOLAMIDE-INDUCED VASODILATION IN THE CAROTID VASCULAR BED IN HEALTHY-VOLUNTEERS

Acetazolamide (ACTZ) vasodilating properties are used for the assessme nt of cerebral vasodilatory reserve not only in cerebral pathology inv estigation, but also in clinical pharmacology studies. However, the ki netics of these vasodilating properties are not clearly established; m oreover, the cerebral selectivity of ACTZ-induced vasodilation has not been demonstrated. To address these issues, we performed an ACTZ test in 9 healthy volunteers and measured noninvasively the effects exerte d by the drug simultaneously on common carotid artery blood flow (CCAB F), middle cerebral artery mean blood flow (BF) velocity (MV) (transcr anial Doppler technique), and facial cutaneous BF (CutBF). The time of the peak increase in MV was variable, occurring between 20 and 40 min after ACTZ, and brief. In addition, simultaneous increases (with vari able mean peak times) occurred in flows in the CCA(+11% at 20 min) and in its intracranial(+25% at 30 min) and extracranial(+134% at 50 min) branches. The first finding suggests that the cerebral effects of ACT Z should be measured repeatedly to detect in each individual subject t he time of MV peak increase; the transcranial Doppler is particularly suitable for such an approach. The second finding suggests that, espec ially in patients, extracranial actions of ACTZ must be taken into acc ount for estimation of the cerebral vasodilatory reserve.