CARBON-MONOXIDE REGULATES CEREBRAL BLOOD-FLOW IN EPILEPTIC SEIZURES BUT NOT IN HYPERCAPNIA

CARBON monoxide (CO) is an endogenously produced gas sharing many prop erties with nitric oxide (NO), notably activating soluble guanylate cy clase and relaxing blood vessels. The brain can generate high quantiti es of CO from a constitutive enzyme, haem oxygenase (HO-2). To determi ne whether CO is involved in the regulatory mechanisms of cerebral blo od flow (CBF), two conditions associated with a reproducible CBF incre ase were studied in rats: epileptic seizures induced by kainate, and h ypercapnia. The HO inhibitor tin protoporphyrin (Sn-PP) did not modify the basal level of CBF, significantly reduced the increase in CBF dur ing status epilepticus, and did not affect the cerebrovascular respons e to hypercapnia. It is concluded that CO participates in the regulati on of CBF in specific conditions, notably those associated with glutam ate release. NeuroReport 9: 2341-2346 (C) 1998 Rapid Science Ltd.