Regional blood-brain barrier permeability to water and cerebral blood flow during status epilepticus: insensitivity to norepinephrine depletion.

To test whether status epilepticus alters regional blood-brain barrier (BBB) permeability to water when systemic hypertension is avoided, and whether central noradrenergic innervation contributes to the regulation of BBB in this setting, Wistar rats with unilateral 6-hydroxydopamine lesion of the nucleus locus coeruleus (LC) were subjected to 8 min of bicuculline-induced status epilepticus while ventilated with 100% oxygen; arterial normotension was preserved by withdrawal of arterial blood as required. Regional cerebral blood flow and permeability-times-surface-area product (PS) for water were measured by a double-label modification of the Kety integral strategy, with [14C]butanol and [3H]water, respectively. In normocapnic control rats, regional cerebral blood flow (rCBF) was 1.92 +/- 0.57 ml/g/min and water extraction fraction was 0.81 +/- 0.08 (S.D.). Values in control rats breathing 100% oxygen were similar. During status epilepticus, rCBF increased two- to three-fold; water extraction fraction declined, but there were no significant side-to-side differences for either rCBF or regional PS product for water in LC-lesioned animals despite an 81% reduction of cortical norepinephrine content on the lesioned side. The PS product for water increased by 42% during status epilepticus, but the flow vs PS-product relationship did not depart from that predicted on the basis of data in control rats. Thus, when systemic hypertension is prevented, brief status epilepticus does not induce abnormal BBB permeability to water, and unilateral LC lesion fails to influence either rCBF or the cerebrovascular PS product for water.