English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We investigated the combined effect of increased brain topical K +  concentration and reduction of the nitric oxide(NO . ) level caused by nitric oxide scavenging or nitric oxide synthase (NOS) inhibition on regional cerebral blood flow and subarachnoid direct current (DC) potential. Using thiopental-anesthetized male Wistar rats with a closed cranial window preparation, brain topical superfusion of a combination of the NO .  scavenger hemoglobin(Hb; 2 mmol/L) and increased K +  concentration in the artificial cerebrospinal fluid ([K + ] ACSF ) at 35 mmol/L led to sudden spontaneous transient ischemic events with a decrease of CBF to 14 ± 7% (n = 4) compared with the baseline (100%). The ischemic events lasted for 53 ± 17 minutes and were associated with a negative subarachnoid DC shift of −7.3 ± 0.6 mV of 49 ± 12 minutes' duration. The combination of the NOS inhibitor N-nitro-L-arginine(L-NA, 1 mmol/L) with [K + ] ACSF  at 35 mmol/L caused similar spontaneous transient ischemic events in 13 rats. When cortical spreading depression was induced by KCl at a 5-mm distance, a typical cortical spreading hyperemia (CSH) and negative DC shift were measured at the closed cranial window during brain topical superfusion with either physiologic artificial CSF (n = 5), or artificial CSF containing increased [K + ] ACSF  at 20 mmol/L (n = 4), [K + ] ACSF  at 3 mmol/L combined with L-NA (n = 10), [K + ] ACSF  at 10 mmol/L combined with L-NA (five of six animals) or [K + ] ACSF  at 3 mmol/L combined with Hb (three of four animals). Cortical spreading depression induced long-lasting transient ischemia instead of CSH, when brain was superfused with either[K + ] ACSF  at 20 mmol/L combined with Hb (CBF decrease to 20± 20% duration 25 ± 21 minutes, n = 4), or [K + ] ACSF  at 20 mmol/L combined with L-NA (n = 19). Transient ischemia induced by NOS inhibition and [K + ] ACSF  at 20 mmol/L propagated at a speed of 3.4 ± 0.6 mm/min, indicating cortical spreading ischemia (CSI). Although CSH did not change oxygen free radical production, as measured on-line by in vivo lucigenin-enhanced chemiluminescence, CSI resulted in the typical radical production pattern of ischemia and reperfusion suggestive of brain damage (n = 4). Nimodipine (2 μg/kg body weight/min intravenously) transformed CSI back to CSH (n = 4). Vehicle had no effect on CSI(n = 4). Our data suggest that the combination of decreased NO .  levels and increased subarachnoid K +  levels induces spreading depression with acute ischemic CBF response. Thus, a disturbed coupling of metabolism and CBF can cause ischemia. We speculate that CSI may be related to delayed ischemic deficits after subarachnoid hemorrhage, a clinical condition in which the release of Hb and K +  from erythrocytes creates a microenvironment similar to the one investigated here.

journal of cerebral blood flow and metabolism

Nitric Oxide Scavenging by Hemoglobin or Nitric Oxide Synthase Inhibition by <i>N</i>-Nitro-L-Arginine Induces Cortical Spreading Ischemia When K<sup>+</sup> Is Increased in the Subarachnoid Space

Nitric Oxide Scavenging by Hemoglobin or Nitric Oxide Synthase Inhibition by N-Nitro-L-Arginine Induces Cortical Spreading Ischemia When K+ Is Increased in the Subarachnoid Space

Nitric Oxide Scavenging by Hemoglobin or Nitric Oxide Synthase Inhibition by N-Nitro-L-Arginine Induces Cortical Spreading Ischemia When K⁺ Is Increased in the Subarachnoid Space