The aim of this study was to develop a nonlinear mixed-effects model for the increase in cerebral oximetry (rSO2) during the rapid introduction of desflurane, and to determine the effect of hypocapnia and N2O on the model. Twelve American Society of Anesthesiologist physical status class 1 and 2 subjects were allocated randomly into an Air and N2O group. After inducing anesthesia, desflurane was then increased abruptly from 4.0 to 12.0%. The PET(CO2), PET(DESF) and rSO2 were recorded at 12 predetermined periods for the following 10 min. The maximum increase in rSO2 reached +24-25% during normocapnia. The increase in rSO2 could be fitted to a four parameter logistic equation as a function of the logarithm of PET(DESF). Hypocapnia reduced the maximum response of rSO2, shifted the EC50 to the right, and increased the slope in the Air group. N2O shifted the EC50 to the right, and reduced the slope leaving the maximum rSO2 unchanged. The N2O-effects disappeared during hypocapnia. The cerebrovascular reactivity of rSO2 to CO2 is still preserved during the rapid introduction of desflurane. N2O slows the response of rSO2. Hypocapnia overwhelms all the effects of N2O.
Adult ; Anesthetics, Inhalation/*pharmacology ; *Cerebral Cortex/blood supply/drug effects/physiology ; Cerebrovascular Circulation/*drug effects/physiology ; Female ; Hemodynamics ; Humans ; Hypocapnia/*metabolism ; Isoflurane/*analogs & derivatives/pharmacology ; Male ; Middle Aged ; Models, Theoretical ; Nitrous Oxide/*metabolism ; *Oximetry ; Random Allocation ; Regional Blood Flow/drug effects

OBJECTIVETo investigate histamine-induced changes of the intracortical vessels in the cortical slice of rat brain.

METHODSImmunohistochemistry was employed to detect the expression of H1 and H2 receptors in the intracortical blood vessels of rats. Histamine-induced constriction of the intracortical blood vessels of the brain slices was observed with differential interference contrast microscope. Measurements of the luminal diameter were made on-line during the course of the experiment and confirmed off-line from the stored images. In order to observe whether histamine H1 and H2 receptors affected histamine-induced constriction, the intracortical blood vessels in the brain slices were pre-treated with H1 receptor antagonist diphenhydramine and H2 receptor antagonist cimetidine.

RESULTSExpression of H1 and H2 receptors was detected in the intracortical blood vessels of the rat brain. Histamine (1-100 micromol/L) induced a concentration-dependent constriction from (1.48-/+0.67)% to (32.91-/+7.91)%. The reactions to each histamine concentration were significantly (P<0.01) different from each other, with the exception of the highest histamine concentrations (30 and 100 micromol/L) when maximal constriction due to histamine were observed (P>0.05). With pre-treatment of the slice with 10 micromol/L diphenhydramine, application of histamine did not elicit constriction. Pre-treatment of the slice with 10 micromol/L cimetidine did not completely inhibit but somehow significantly weakened vascular constriction in response to histamine treatment at 10 and 30 micromol/L (P<0.05).

CONCLUSIONHistamine can induce constriction of the intracortical blood vessels, which is mediated by H1 receptor.

Animals ; Blood Vessels ; drug effects ; metabolism ; physiology ; Cerebral Cortex ; blood supply ; Cimetidine ; pharmacology ; Diphenhydramine ; pharmacology ; Histamine ; pharmacology ; Histamine H1 Antagonists ; pharmacology ; Histamine H2 Antagonists ; pharmacology ; In Vitro Techniques ; Male ; Rats ; Rats, Sprague-Dawley ; Receptors, Histamine H1 ; metabolism ; physiology ; Receptors, Histamine H2 ; metabolism ; physiology ; Vasoconstriction ; drug effects

OBJECTIVETo study the influence of conditioned medium of rat brain microvascular endothelial cells on mitochondrial function of cortical neurons and the protective effect of Tongluo Jiunao Injection (TJI) on it.

METHODSFour kinds of conditioned endothelial cell (EC) cultured medium were prepared, i.e. the N-CM medium prepared by EC cultured in the normal conditioned medium without any treatment; the NT-CM prepared by EC cultured in N-CM and treated with TJI 1 microl/ml for 10 h; the I-CM prepared by EC cultured in the non-glucose kreb medium under hypoxia condition; and the IT-CM by EC pre-treatce with TJI 1 microl/ml for 4 h and cultured as that of I-CM. The levels of neuronic mitochondrial activity, membrane potential (MMP) and cytochrome C (Cyt C) were determined before and after the glucose-oxygen deprived model neurons of brain cortex being cultured with different kinds of conditioned EC cultured medium for assessing the effects of these media on mitochondria of injured neuron.

RESULTSAs compared with those of the normal neuron, the mitochondrial activity and MMP of all injured neurons decreased and Cyt C level increased significantly. But comparison of these indexes among neurons cultured with different conditioned EC culture media showed that the greatest extent abnormality revealed in the N-CM cultured neurons, which even greater than that in the model neuron; while that was less in the N-CM cutured neuron than in model neuron; as for those cultured in the NT-CM and IT-CM, i.e. the TJI treated cuture medium, the abnormal changes were reduced significantly when compared with those cultured in medium untreated with TJI (N-CM and I-CM), respectively (all P < 0.05).

CONCLUSIONThe paracrine secretion of the brain microvascular endothelial cells has evident regulatory effect on survival of the injured neurons, which might possibly be related to its protective effect on neuron mitochondrial function, and TJI could enhance the protective effect.

Animals ; Capillaries ; cytology ; Cells, Cultured ; Cerebral Cortex ; blood supply ; cytology ; Culture Media, Conditioned ; pharmacology ; Cytochromes c ; metabolism ; Drugs, Chinese Herbal ; pharmacology ; Endothelial Cells ; cytology ; drug effects ; ultrastructure ; Male ; Membrane Potential, Mitochondrial ; drug effects ; Mitochondria ; drug effects ; metabolism ; physiology ; Neurons ; cytology ; drug effects ; ultrastructure ; Rats