Background & Objectives: Many researches have been conducted on autoregulation of cerebral blood flow (CBF), but its possible variations coincidence with postvagal tachycardia have not yet been studied. The present study searched for the effect of this phenomenon on CBF in young and middle-aged persons.

 Methods: 52 healthy volunteers including 13 young males (mean age 23.9±0.8), 13 young females (mean age 24.2±0.7), 13 middle-aged males (mean age 58±0.9) and 13 middle-aged females (mean age 56.4±0.7) went under the study. Flow velocity in middle cerebral artery (MCA) was assessed using transcranial Doppler (TCD) ultrasonography apparatus. Eckberg’s neck suction device was utilized to stimulate carotid baroreceptors. The data were analyzed using Minitab and SPSS software (rel. 10).

 Results: Concomitant to the carotid baroreceptors stimulation there was a significant reduction in heart rate in all groups (p<0.05), but mean cerebral blood flow did not change significantly. After ending the carotid baroreceptors stimulation and concomitant to PVT, mean cerebral blood flow increased in all groups except middle-aged males. This increase in CBF became significant in middle-aged females (p<0.05).

 Conclusion: The results of the present study indicate that cerebral blood flow autoregulation act effectively concomitant to acute stimulation of carotid baroreceptors and this efficacy is maintained until the middle-age, but when faced with PVT, cerebral blood flow autoregulation dose not act effectively.

  Background & objectives: Ischemic stroke is the third leading cause of death and disability in most of the human societies. There is no effective treatment due to complexity of the pathophysiological mechanisms. Today, more researches are designed to introduce involving factors and new treatment strategies in brain ischemia. The objective of this study is to introduce an experimental model of the focal cerebral ischemia in rat with increased success rate and low mortality rate.

  Methods: In this research 32 male rats (Sprague-Dawley) were studied as in four experimental groups. Animals were anesthetized with chloral hydrate (400mg/kg, ip). Focal cerebral ischemia was induced by intraluminal filament method. A silicon coated nylon filament was used for middle cerebral artery occlusion. Regional cerebral blood flow was monitored by laser Doppler flowmetery to guide the insertion of the filament into the vascular pathway. 24 hours after ischemia (90minutes), animals were assessed for neurological outcome, infarct volume and brain edema formation. A new and reformed neurological test was used for evaluation of neurological deficits. 2 - millimeter coronal sections were collected from 6 levels of the brain and stained, digitized and quantified by using an image analysis system. Ischemic brain edema formation was investigated by brain water content detection.

  Results: Induction of ischemia in ischemic group, seriously caused impairment of motor functions (neurological deficit score 4±0.5) While sham operated rats had no motor deficit and infarction. Mean total infarct volume of left (ischemic) hemisphere was 402±43 mm³ and 62.7 percent of infarction occurred in cortical regions of the brain. Induction of focal cerebral ischemia in the left (ischemic) hemisphere of the brain significantly increased water content (84±0.23 percent) compared to both hemispheres of sham group and right hemisphere of the same group. Success rate of ischemia induction was 100 percent and there was no mortality due to technical problems.

  Conclusion: Our findings indicate that continuous recording of regional cerebral blood flow using laser Doppler flowmeter had significant role in increasing success rate and lowering mortality rate in the present model of ischemic rat. This experimental model with high success rate and low limitation can be used for brain ischemia studies and evaluating new therapeutic strategies.