Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism
-
J. Cereb. Blood Flow Metab. · Jun 1989
Acute thrombotic infarction suppresses metabolic activation of ipsilateral somatosensory cortex: evidence for functional diaschisis.
To study the effects of focal infarction on the capacity for functional activation of an ipsilateral somatosensory system remote from the lesion, we produced a small thrombotic infarct in the left frontal pole of male Wistar rats by a photochemical method. Five days later, the awake, restrained rats received tactile stimulation of the large whiskers (vibrissae) of the right side of the face, while a double-label 14C-autoradiographic study of local CMRglc (lCMRglc) and local CBF (lCBF) was performed. Unlesioned and unstimulated animals served as controls. ⋯ The ventrobasal thalamus, similarly, failed to increment its lCMRglc with vibrissae stimulation, whereas activation of the trigeminal nucleus was not suppressed. Similar trends were observed in the normalized lCBF data. These observations, which establish that a small frontal infarct is capable of suppressing normal physiological activation in remote ipsilateral brain structures, may have important implications with respect to suppression and recovery of function in human ischemic stroke.
-
J. Cereb. Blood Flow Metab. · Dec 1988
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. III. Changes following ischaemia.
CBF has been measured with the hydrogen clearance technique in the two cerebral hemispheres of the gerbil under halothane anaesthesia. At the same time, intracellular pH and the concentrations of lactate and high-energy phosphates were measured in the brain using 1H and 31P nuclear magnetic resonance spectroscopy. Flow and metabolism have been followed during either a 15- or a 30-min ischaemic period (induced by bilateral carotid occlusion) and for up to 1 h of recovery. ⋯ High-energy phosphate levels and pH returned to control within approximately 20 min of the end of the ischaemic period. Lactate clearance, following a 30-min occlusion, was slower than the recovery of pH. The concentration of free ADP, calculated from the creatine kinase equilibrium, was lower during the recovery phase than under control conditions.
-
J. Cereb. Blood Flow Metab. · Oct 1988
Reduction of cerebrospinal fluid pressure by hypocapnia: changes in cerebral blood volume, cerebrospinal fluid volume and brain tissue water and electrolytes. II. Effects of anesthetics.
Part I of these studies (Artru, 1987) examined how cerebral blood volume (CBV), CSF volume, and brain tissue water and electrolytes determined CSF pressure during 4 h of hypocapnia in sedated dogs. The three groups reported were: hypocapnia (PaCO2 20 mm Hg) with no intracranial mass (group 1), intracranial mass (epidural balloon, CSF pressure 35 cm H2O) but no hypocapnia (group 2), and intracranial mass with hypocapnia used to lower CSF pressure (group 3). It was found that in dogs with an intracranial mass (group 3) the CSF pressure-lowering effect of hypocapnia was sustained for 4 h due to improved reabsorption of CSF, decrease of CSF volume to offset reexpansion of CBV and no increase in the sum of CSF volume and CBV. ⋯ With halothane the intracranial volume increase was comprised chiefly of cerebral blood and with enflurane the intracranial volume increase was comprised chiefly of CSF. When isoflurane, fentanyl, or thiopental were used for anesthesia, the CSF pressure-lowering effect of hypocapnia was sustained. Ra did not increase and the sum of CBV and CSF volume remained reduced.
-
J. Cereb. Blood Flow Metab. · Aug 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. II. Changes during ischaemia.
CBF has been measured with the hydrogen clearance technique in the two cerebral hemispheres of the gerbil under halothane anesthesia. 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 spectroscopy. We demonstrate a threshold flow value for the metabolic changes associated with energy failure at a level similar to the values previously reported for electrical failure and tissue water accumulation, but higher than that associated with breakdown of extracellular potassium homeostasis.
-
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.