Blood pressure lowering after experimental cerebral ischemia provides neurovascular protection

Hazem F. Elewa, Anna Kozak, Maribeth H Johnson, Adviye Ergul, Susan C. Fagan

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

BACKGROUND: There is evidence that acutely elevated blood pressure (BP) after stroke is associated with increased cerebral hemorrhage and edema. Previous experiments in our laboratory have shown that candesartan 1 mg/kg administered after reperfusion in a model of hypertension after experimental ischemic stroke reduces neurovascular damage and improves outcome. These results could be either mediated by BP lowering or a BP-independent cerebrovascular protective effect. OBJECTIVES: To determine the contribution of BP lowering to the neurovascular protection previously reported with candesartan after stroke. METHODS: Male Wistar rats (280-305 g) underwent 3 h of middle cerebral artery occlusion (MCAO). At reperfusion, either hydralazine 1 mg/kg (n = 8), enalapril 5 mg/kg (n = 7) or enalapril 10 mg/kg (n = 8) were administered intravenously. BP was measured by telemetry for 2 days before and 24 h after MCAO. After neurological function was assessed, brain tissue was processed for infarct size and hemoglobin content analyses. RESULTS: Mean arterial pressure (MAP) increased from 92 to 124 mmHg immediately upon MCAO and decreased to 112 mmHg after reperfusion, remaining elevated for 24 h (P < 0.0001) in the saline group. Hydralazine reduced MAP (P = 0.048) and infarct size (53 versus 30%, P = 0.0083), and there was a trend towards decreased hemoglobin content. Enalapril 5 mg/kg did not significantly change MAP or other outcomes. Enalapril 10 mg/kg reduced MAP (P < 0.0001) and infarct size (53 versus 29%, P = 0.003). There was an intermediate effect on both hemoglobin content and neurological function, neither one was significant. The time course of BP lowering varied with each treatment. CONCLUSION: Acute BP lowering after reperfusion in acute ischemic stroke is an effective strategy to achieve neurovascular protection. The rate, extent and mechanism of BP lowering may determine the magnitude of protection.

Original languageEnglish (US)
Pages (from-to)855-859
Number of pages5
JournalJournal of Hypertension
Volume25
Issue number4
DOIs
StatePublished - Apr 1 2007

Fingerprint

Brain Ischemia
Blood Pressure
Enalapril
Reperfusion
Middle Cerebral Artery Infarction
Arterial Pressure
Stroke
Hydralazine
Hemoglobins
Telemetry
Brain Edema
Cerebral Hemorrhage
Wistar Rats
Hypertension
Brain

Keywords

  • Blood pressure
  • Neurovascular protection
  • Stroke

ASJC Scopus subject areas

  • Internal Medicine
  • Endocrinology

Cite this

Blood pressure lowering after experimental cerebral ischemia provides neurovascular protection. / Elewa, Hazem F.; Kozak, Anna; Johnson, Maribeth H; Ergul, Adviye; Fagan, Susan C.

In: Journal of Hypertension, Vol. 25, No. 4, 01.04.2007, p. 855-859.

Research output: Contribution to journalArticle

Elewa, Hazem F. ; Kozak, Anna ; Johnson, Maribeth H ; Ergul, Adviye ; Fagan, Susan C. / Blood pressure lowering after experimental cerebral ischemia provides neurovascular protection. In: Journal of Hypertension. 2007 ; Vol. 25, No. 4. pp. 855-859.
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AU - Fagan, Susan C.

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AB - BACKGROUND: There is evidence that acutely elevated blood pressure (BP) after stroke is associated with increased cerebral hemorrhage and edema. Previous experiments in our laboratory have shown that candesartan 1 mg/kg administered after reperfusion in a model of hypertension after experimental ischemic stroke reduces neurovascular damage and improves outcome. These results could be either mediated by BP lowering or a BP-independent cerebrovascular protective effect. OBJECTIVES: To determine the contribution of BP lowering to the neurovascular protection previously reported with candesartan after stroke. METHODS: Male Wistar rats (280-305 g) underwent 3 h of middle cerebral artery occlusion (MCAO). At reperfusion, either hydralazine 1 mg/kg (n = 8), enalapril 5 mg/kg (n = 7) or enalapril 10 mg/kg (n = 8) were administered intravenously. BP was measured by telemetry for 2 days before and 24 h after MCAO. After neurological function was assessed, brain tissue was processed for infarct size and hemoglobin content analyses. RESULTS: Mean arterial pressure (MAP) increased from 92 to 124 mmHg immediately upon MCAO and decreased to 112 mmHg after reperfusion, remaining elevated for 24 h (P < 0.0001) in the saline group. Hydralazine reduced MAP (P = 0.048) and infarct size (53 versus 30%, P = 0.0083), and there was a trend towards decreased hemoglobin content. Enalapril 5 mg/kg did not significantly change MAP or other outcomes. Enalapril 10 mg/kg reduced MAP (P < 0.0001) and infarct size (53 versus 29%, P = 0.003). There was an intermediate effect on both hemoglobin content and neurological function, neither one was significant. The time course of BP lowering varied with each treatment. CONCLUSION: Acute BP lowering after reperfusion in acute ischemic stroke is an effective strategy to achieve neurovascular protection. The rate, extent and mechanism of BP lowering may determine the magnitude of protection.

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