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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The presence and distribution of a cerebrovascular cholinergic system were studied in goats. Regional cerebral blood flow was measured in the parietal cerebral cortex, caudate nucleus, and white matter by the hydrogen clearance technique in unanesthetized goats. Intravenous low doses of physostigmine, but not of neostigmine, significantly increased regional blood flow without changing mean arterial blood pressure or behavior. Increases of blood flow were greater in cerebral cortex and caudate nucleus than in white matter although the vasodilation induced by hypercapnia was similar in the three regions. Intracerebral microvessels were isolated from cerebral cortex, caudate nucleus, and white matter to evaluate choline acetyltransferase activity as a marker for perivascular cholinergic nerves. The enzyme level was higher in vessels from cerebral cortex and caudate nucleus than in vessels from white matter, which is in accordance with the functional data. These results suggest the presence of a cholinergic perivascular innervation system in intracerebral microvessels. Such innervation has a nonhomogeneous distribution throughout the brain and might be implicated in the local regulation of cerebral blood flow.
Stroke 1988 Jun
PMID:Regional differences in cerebrovascular cholinergic innervation in goats. 337 65

The present study was designed to clarify the effect of brovincamine fumarate (BV 26-723: BV) on the degree of cerebral ischemia acutely induced by bilateral common carotid artery ligation (BLCL) in stroke-resistant spontaneously hypertensive rats (SHRSR). BV was administered to SHRSR by intraperitoneal infusion (I.P.) of 30 mg/kg (BV 30 mg/kg group), 60 mg/kg (BV 60 mg/kg group) and 0.9% saline was similarly injected to SHRSR (control group) before and immediately after BLCL. Cerebral blood flow (rCBF) in the thalamus was measured by hydrogen clearance technique before and until 3 hr of BLCL periodically. The brain metabolites (ATP, lactate, pyruvate) were determined by the enzymatic method and the brain water content was measured by freeze-dry method 3 hr after BLCL. The histopathological changes in brain vessels were observed by scanning electron microscopy (SEM) 3 hr after BLCL. The rCBF of three groups were identical before BLCL. However, the rCBF of BV 30 mg/kg group was statistically higher than in control group until 2 hr after BLCL, and that of BV 60 mg/kg group was significantly higher even 3 hr after BLCL. In measurements of the brain metabolites after BLCL, ATP and pyruvate levels in both the BV 30 mg/kg and 60 mg/kg groups were statistically higher than the control group. And brain lactate concentrations in both the BV 30 mg/kg and 60 mg/kg groups were significantly lower than the control group. The brain water content of BV 30 mg/kg and 60 mg/kg groups were significantly lower then the control group after BLCL.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Effect of brovincamine fumarate on cerebral ischemia acutely induced by BLCL in SHRSR]. 344 48

Combined Positron Emission Tomography (PET) and Proton Magnetic Resonance Imaging (MRI) study were performed in six patients with chronic supratentorial stroke to investigate whether remote hypometabolic regions revealed by PET showed any abnormality on MRI. Either regional oxygen consumption (n = 4) or glucose utilization (n = 2) were measured using PET and the 15O steady state 18FDG technique, respectively. Four patients, with deeply located brain lesions, showed a significant metabolic reduction in the overlying cerebral cortex. In the remaining two patients, affected by a large cortical infarct, there was a significant crossed cerebellar hypometabolism. The MRI weighted by the parameters spin density (rho), spin lattice (T1) and spin-spin (T2) relaxation times were obtained employing various sequences in the same subjects. In no patient did the MRI show any contrast modification in these hypometabolic remote regions, suggesting that subtle loss of tissue and/or biochemical change do not underlie the reduction in metabolic rate.
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PMID:Remote metabolic effects of cerebrovascular lesions: magnetic resonance and positron tomography imaging. 349 45

To test applicability of monitoring regional spinal cord blood flow by measuring regional epidural blood flow, both were simultaneously measured by the hydrogen clearance method in response to changes in PaCO2 and mean arterial blood pressure in rats anesthetized with pentobarbital. An excellent correlation was found between regional spinal and epidural blood flow over a physiological range of PaCO2 (27.8-66.7 torr) and blood pressure (30-130 torr), while a poor correlation was demonstrated between regional spinal or epidural blood flow and regional muscle blood flow in response to these same physiological parameters. Moreover, the rates of change in regional spinal and epidural blood flows were almost the same in response to both PaCO2 and blood pressure. These results suggest that both regional spinal and epidural blood flow are regulated by a similar mechanism and suggest that regional spinal cord blood flow can be monitored by regional epidural blood flow.
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PMID:Relation between spinal cord and epidural blood flow. 368 88

The present study was designed to investigate the effect of acute sympathetic denervation on the regional cerebral blood flow (CBF) autoregulation during acute elevation of blood pressure in spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY). CBF to the parietal cortex and thalamus was measured by the hydrogen clearance method and, to test autoregulation, systemic arterial blood pressure was elevated by intravenous infusion of phenylephrine. Superior cervical ganglia were removed on both sides to interrupt sympathetic innervation in the deeper structures of the brain. Acute bilateral sympathetic denervation did not alter the resting blood pressure or CBF in either SHR or WKY. In innervated SHR, resting mean arterial pressure (MAP) was 165 +/- 5 mm Hg (mean +/- SEM) and the upper limit of autoregulation in the cortex was 210 +/- 3 mm Hg, which was significantly lower than that in the thalamus (229 +/- 3 mm Hg, p less than 0.02). In bilaterally denervated SHR, the upper limits were lowered to 193 +/- 4 mm Hg in the cortex (p less than 0.02 vs. innervated SHR) and to 207 +/- 5 mm Hg in the thalamus (p less than 0.02 vs. innervated). In WKY, resting MAP was approximately 55 mm Hg lower than that in SHR. Acute denervation reduced the upper limits from 142 +/- 3 mm Hg to 130 +/- 4 in the cortex (p less than 0.05) and from 158 +/- 4 to 145 +/- 4 in the thalamus (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Regional cerebral blood flow autoregulation in normotensive and spontaneously hypertensive rats--effects of sympathetic denervation. 376 71

Twenty-four cats had an intravenous infusion of either Fluosol or saline and then were subjected to 2 hours of middle cerebral artery occlusion. All the animals infused with Fluosol and one-half the animals infused with saline were ventilated with 100% O2. Tissue oxygen availability and regional cerebral blood flow were measured by platinum electrodes using direct voltage recordings for oxygen measurements and hydrogen clearance curves for measurements of cerebral blood flow. With 100% oxygenation tissue oxygen availability increased significantly in the Fluosol treated animals, however, during the time of ischemia oxygen availability decreased below baseline values to about an equal level whether the animals were treated with Fluosol or saline. Regional cerebral blood flow fell to a similar value in all groups during the time of occlusion. One hour after reperfusion blood flow increased considerably above baseline values in all groups and oxygen availability also increased in all groups but particularly in the Fluosol treated animals. Overall mortality and the size of infarction 1 week after the ischemic insult were not significantly different in the three groups. Mortality was directly related to the size of the infarct which, in turn, was related to the degree of ischemia during the time of occlusion.
Stroke
PMID:Effect of Fluosol on oxygen availability, regional cerebral blood flow, and infarct size in a model of temporary focal cerebral ischemia. 376 70

Cerebral blood flows (CBF) were measured in the parietal cortex, the thalamus and the cerebellum by the hydrogen clearance technique in anesthetized spontaneously hypertensive rats, of which hypertension was treated for 16 weeks (long-term) or 8 weeks (short-term) with antihypertensive agents of hydralazine and guanethidine. As compared to non-treated control animals, CBF in the three regions were significantly increased while the calculated cerebrovascular resistances (CVR) were decreased in hypertension-treated animals. Such CBF and CVR changes were greater in SHR with long-term than short-term therapy. Both an increase in CBF and a decrease in CVR were closely related to a fall in the blood pressure. From the present results, it was concluded that earlier and longer treatment of hypertension could lessen or even prevent the increased CVR due to the hypertensive vascular changes, and increase CBF as a result.
Stroke
PMID:Effects of long-term antihypertensive treatment on cerebral, thalamic and cerebellar blood flow in spontaneously hypertensive rats (SHR). 376 72

Autoregulation of cerebral (CBF) and cerebellar blood flow (CeBF) was studied before, during and after acutely induced cerebral ischemia in spontaneously hypertensive rats. Cerebral ischemia of the supratentorial portion was induced for one hour by bilateral carotid artery ligation (BCL). The animals were artificially ventilated and the blood flow was measured with a hydrogen clearance technique. To test the autoregulation, the blood pressure was stepwise lowered by bleeding and maintained at a new level, i.e. 15% or 30% lower than the baseline values before, during and after cerebral ischemia. At the preischemic state, CBF and CeBF were 52.1 +/- 6.2 and 58.9 +/- 4.6 ml/100 g/min (mean +/- SEM), of which autoregulations were normally preserved. Following BCL, CBF was markedly decreased to about 10% of control value while CeBF was minimally reduced to 46.9 +/- 8.6 ml/100 g/min (80%). At the ischemic state, CBF became almost zero flow during hypotension. CeBF was also reduced to 74% and further to 58% of the resting value by 15% and 30% decrease in the blood pressure, respectively, indicating impaired CeBF autoregulation. At the 30 min post-ischemic state, CBF was recovered to 48.0 +/- 4.9 and CeBF to 53.9 +/- 5.4 ml/100 g/min. Autoregulation of CBF was still abolished, whereas CeBF was kept constant by 15% fall of blood pressure and slightly reduced to 84% by 30% hypotension, indicating almost recovery of CeBF autoregulation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cerebral and cerebellar blood flow autoregulations in acutely induced cerebral ischemia in spontaneously hypertensive rats--transtentorial remote effect. 381 Jul 34

Prolonged normoxic hypercapnia initially caused an increase in canine cerebral blood flow, as measured by the radioactive microsphere technique, accompanied by a decrease in cerebrovascular resistance. These effects persisted for 3 hours. An adaptive decrease in cerebral blood flow and increase in cerebrovascular resistance were seen when hypercapnia was maintained for an additional 3 hours. Regional variations occurred; those areas with the greatest initial hypercapnic blood flow (cortex, caudate nucleus) showed a greater rate of decay of flow over time. Cerebrospinal fluid pH, initially acidotic during hypercapnia, increased over the subsequent 5 hours from 6.99 +/- 0.02 to 7.13 +/- 0.02. This was accompanied by an increase in the cerebrospinal fluid bicarbonate ion concentration from a normocapnic baseline of 19.6 +/- 0.6 to 26.2 +/- 4 mEq/l. Total and regional cerebral blood flow were linearly related to cerebrospinal fluid pH (R2 = 0.97). Extrapolation of a full adaptive return of flow to baseline indicated a shift in the cerebrovascular sensitivity to extracellular hydrogen ion concentration during prolonged hypercapnia.
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PMID:Time-dependent effects of prolonged hypercapnia on cerebrovascular parameters in dogs: acid-base chemistry. 381 Jul 47

Acute focal ischemia was created in 10 cats by unilateral retro-orbital middle cerebral artery (MCA) occlusion. Regional cerebral blood flow (CBF) was determined utilizing the hydrogen clearance technique from electrode recordings within the gray matter and white matter of the ectosylvian gyrus of both hemispheres. The somatosensory evoked potential (SSEP) was obtained during contralateral median nerve stimulation. When the MCA was clipped the white and gray matter blood flows in the ipsilateral ectosylvian gyrus were reduced to 14.8 +/- 19.6% and 19.3 +/- 23.7% of control, and the cortical component of the SSEP was abolished. In the contralateral hemisphere an average increase of 3.5% above the control latency and a 10% mean depression in the amplitude of the cortical component of the SSEP were observed following occlusion. CBF in the contralateral hemisphere was unaffected by the MCA clip. Infusion of saline or dextran to lower the hematocrit by approximately 45% did not significantly improve blood flow or restore the SSEP in the hemisphere ipsilateral to the MCA clip. However, significant increases in the contralateral hemisphere gray matter CBF occurred following hemodilution while the latency of the cortical component of the SSEP in this same hemisphere was significantly extended. Elevations in gray and white matter blood flows were achieved in the experimental hemisphere of 3 of 10 cats suggesting a wide range of variation in the collateral circulation.
Stroke
PMID:Failure of the somatosensory evoked potential following middle cerebral artery occlusion and high-grade ischemia in the cat--effects of hemodilution. 394 81


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