Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism
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J. Cereb. Blood Flow Metab. · Jun 1987
Comparative StudyHistopathological and hemodynamic consequences of complete versus incomplete ischemia in the rat.
The primary objective of this study was to compare the histopathological consequences of complete versus incomplete ischemia under experimental conditions that limit lactate accumulation. Fasted rats underwent 1 h of either complete or incomplete ischemia by a procedure combining bilateral common carotid artery occlusion, halothane-induced systemic hypotension, and CSF pressure elevation. Histopathological outcome was evaluated 4 h later and was graded on a 4-point scale. ⋯ When recirculation was instituted for 1 h following 1 h of complete ischemia, regions of nonperfusion were detected autoradiographically. Thus, when the degree of lactic acidosis is controlled, prolonged periods of complete ischemia result in a more severe pathological outcome compared to incomplete ischemia. Focally impaired postischemic cerebral perfusion appears to be an important factor in infarct formation under the present experimental conditions.
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J. Cereb. Blood Flow Metab. · Apr 1987
Acute cerebral ischaemia: concurrent changes in cerebral blood flow, energy metabolites, pH, and lactate measured with hydrogen clearance and 31P and 1H nuclear magnetic resonance spectroscopy. I. Methodology.
CBF has been measured with the hydrogen clearance technique in the two cerebral hemispheres of the gerbil under halothane anaesthesia. This has been correlated with changes in local pH, tissue lactate, and phosphorus energy metabolites measured in the same animals with 1H and 31P nuclear magnetic resonance (NMR) spectroscopy. ⋯ The metabolic effects of reperfusion are also shown. The model allows the definition of the time course of the metabolic consequences of regional ischaemia and reperfusion in individual laboratory animals.
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J. Cereb. Blood Flow Metab. · Aug 1986
Effect of transient cerebral ischemia on metabolic activation of a somatosensory circuit.
The effects of transient ischemia on the metabolic responsiveness of a well-defined brain circuit were investigated with [14C]2-deoxyglucose autoradiography. Rats underwent 30 min of severe forebrain ischemia followed by postischemic recirculation periods of 1, 2, 3, 5, and 10 days. At these times, unilateral whisker stimulation was carried out, resulting in the metabolic activation of the whisker barrel circuit. ⋯ Glucose utilization within nonactivated relay stations, depressed at earlier time periods, had also returned to control levels by day 5. At both 5 and 10 days, an altered laminar pattern of elevated glucose utilization was apparent within the activated barrel field region, with local CMRglu being depressed in layer V compared with control values. These results demonstrate that periods of transient ischemia produce both reversible and longer-lasting effects on the ability of the CNS to respond to peripheral activation.(ABSTRACT TRUNCATED AT 250 WORDS)
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J. Cereb. Blood Flow Metab. · Jun 1986
Brain luxury perfusion during cardiopulmonary bypass in humans. A study of the cerebral blood flow response to changes in CO2, O2, and blood pressure.
CBF and related parameters were studied in 68 patients before, during, and following cardiopulmonary bypass. CBF was measured using the intraarterial 133Xe injection method. The extracorporeal circuit was nonpulsatile with a bubble oxygenator administering 3-5% CO2 in the main group of hypercapnic patients (n = 59) and no CO2 in a second group of hypocapnic patients. ⋯ The degree of hemodilution neither affected the CO2 response nor impaired CBF autoregulation, although, as would be expected, it influenced CBF: In 33 women CBF was 55 ml/100 g/min at an Htc of 24%, as compared with 42 ml/100 g/min in 35 men (Htc = 28%). High PaO2 was a vasoconstrictor, the autoregulatory plateau being narrowed. The lower limit of autoregulation was shifted to a higher pressure when PaO2 was low.