Comparison of haemodynamic responses to tracheal intubation using the Airway Scope(®) and Macintosh laryngoscope in normotensive and hypertensive patients.

We compared the effects of the Airway Scope(®) on haemodynamic responses during tracheal intubation with those of direct laryngoscopy in normotensive and hypertensive patients. The systolic blood pressure, diastolic blood pressures and heart rate were recorded: (a) before anaesthesia; (b) immediately before intubation; (c) at intubation; and (d) 1, 2, 3, 4 and 5 min after intubation. In normotensive patients, the increase in blood pressure and heart rate over time were significantly lower with the Airway Scope than with the Macintosh laryngoscope (p < 0.003). In hypertensive patients, however, there was no difference in the changes over time in any of these haemodynamic measures between the two devices (p > 0.05). We conclude that the Airway Scope attenuates haemodynamic responses to tracheal intubation in comparison with the laryngoscope in normotensive but not in hypertensive patients. You can respond to this article at http://www.anaesthesiacorrespondence.com.

Chronic ethanol consumption does not affect action of propofol on rat hippocampal acetylcholine release in vivo.

BACKGROUND: The aim of this study was to examine ethanol-consumption-related changes in the effects of propofol on rat hippocampal acetylcholine (ACh) release. METHODS: Male Sprague-Dawley rats received a solution of ethanol (20% v/v) for 24 weeks while controls received tap water. The effects of propofol were examined by in vivo microdialysis, with ACh release from the hippocampal regions determined by high-performance liquid chromatography with electrochemical detection (HPLC-ECD). RESULTS: Propofol 50 mg kg(-1) i.p. significantly decreased basal hippocampal ACh release in ethanol-treated and control rats by 50.4 (sem 4.7)% and 38.3 (11.1)%, respectively. Propofol 100 mg kg(-1) i.p. significantly decreased basal hippocampal ACh release in ethanol-treated and control rats by 67.5 (3.7)% and 55.9 (7.4)%, respectively. The reduction in hippocampal ACh release induced by 50 or 100 mg kg(-1) i.p. propofol was not significantly different between ethanol-treated and control rats. There was no significant difference in the duration of sleep between the two groups. CONCLUSIONS: These results demonstrate that chronic ethanol consumption does not augment the inhibitory actions of propofol on rat hippocampal ACh release. These findings appear to be inconsistent with the notion that chronic ethanol intake enhances the propofol-induced inhibition of the hippocampal cholinergic system and related mental dysfunction.

Opposite effects of depressant and convulsant barbiturate stereoisomers on acetylcholine release from the rat hippocampus in vivo.

BACKGROUND: It has been shown that the R(-) isomer of 1-methyl-5-phenyl-5-propyl barbituric acid (MPPB) induces loss of the righting reflex (LRR), while S(+)-MPPB causes pure excitatory effects, including convulsions, in vivo. METHODS: We studied the effects of the depressant and convulsant MPPB stereoisomers on rat hippocampal acetylcholine (ACh) release in vivo, using a brain microdialysis technique in freely moving animals. RESULTS: R(-)-MPPB 60 and 90 mg x kg(-1) i.p. decreased ACh release from the rat hippocampus by 44.1 (8.2)% and 60.8 (8.2)%, respectively. In the hippocampus, the local application of bicuculline, a gamma-aminobutyric acid (GABA)(A) receptor antagonist, 1 micromol litre(-1) antagonized the inhibitory effects of R(-)-MPPB 90 mg x kg(-1) i.p. In contrast, R(-)-MPPB, S(+)-MPPB 60 and 90 mg x kg(-1) i.p. increased ACh release to 151.8 (6.8)% and 169.6 (11.1)% of the basal release, respectively. CONCLUSIONS: Our results demonstrated that R(-)-MPPB decreased, while S(+)-MPPB increased, rat hippocampal ACh release and that the inhibitory effects of R(-)-MPPB may involve the GABA(A) receptor in vivo. These data imply that changes in hippocampal ACh due to these agents may be related to their central inhibitory and stimulatory actions in vivo.

An L-dopaergic relay from the posterior hypothalamic nucleus to the rostral ventrolateral medulla and its cardiovascular function in anesthetized rats.

We have proposed that L-3,4-dihydroxyphenylalanine (L-DOPA) is a neurotransmitter in the central nervous system [Misu Y. et al. (1996) Prog. Neurobiol. 49, 415-454]. Herein, we attempt to clarify whether lesions in the posterior hypothalamic nucleus decrease the tissue content of L-DOPA in the rostral ventrolateral medulla. We also attempt to clarify whether or not endogenous L-DOPA is evoked by electrical stimulation of the posterior hypothalamic nucleus. It is possible that evoked L-DOPA functions as a transmitter candidate to activate pressor sites of the rostral ventrolateral medulla in anesthetized rats. Electrolytic lesions were made in the bilateral posterior hypothalamic nucleus by a monopolar direct current of 2 mA for 10 s, 10 days before measurements. The effect of the lesions was to selectively decrease the tissue content of L-DOPA by one-half in the right rostral ventrolateral medulla. Decreases in the amounts of dopamine, noradrenaline or adrenaline were not observed. Decreases were also not evident in the right caudal ventrolateral medulla. During microdialysis of the right rostral ventrolateral medulla, extracellular basal levels of L-DOPA and three types of catecholamine were consistently detectable by high-performance liquid chromatography with electrochemical detection. Tetrodotoxin (1 microM) perfused into the right rostral ventrolateral medulla gradually decreased basal levels of L-DOPA by 25%; it decreased basal levels of noradrenaline and adrenaline by 25-30% and dopamine levels by 40%. Intensive electrical stimulation of the ipsilateral posterior hypothalamic nucleus (50 Hz, 0.3 mA, 0.1 ms duration, twice for 5 min at an interval of 5 min) selectively caused the release of L-DOPA in a repetitive and constant manner. The stimulation was accompanied by hypertension and tachycardia. However, catecholamines were not released. Tetrodotoxin suppressed the release of L-DOPA, but partially inhibited hypertension with only a slight inhibition of tachycardia evoked by stimulation of the posterior hypothalamic nucleus. L-DOPA methyl ester, a competitive L-DOPA antagonist, was bilaterally microinjected into pressor sites of the rostral ventrolateral medulla at 1.5 microg x 2 and 3 microg x 2. The antagonist dose-dependently and consistently antagonized pressor and tachycardiac responses to mild transient stimulation of the unilateral posterior hypothalamic nucleus (33 Hz, 0.2 mA, 0.1 ms duration, for 10 s). In addition, the antagonist alone (3 microg x 2) elicited hypotension and bradycardia. These results show that an L-DOPAergic relay may project from the posterior hypothalamic nucleus directly to pressor sites of the rostral ventrolateral medulla and/or indirectly to certain neurons near pressor sites in microcircuits of the same region. When released, L-DOPA appears to function tonically to activate pressor sites; it also appears to be involved in the maintenance and regulation of blood pressure and heart rate.

An L-DOPA-like depressor action of L-threo-dihydroxyphenyl-serine in the rat caudal ventrolateral medulla.

We have proposed that L-3,4-dihydroxyphenylalanine (L-DOPA) is a neurotransmitter and/or neuromodulator in the central nervous system (1). In this study, we investigated whether or not L-threo-dihydroxyphenylserine (L-threo-DOPS), a synthetic amino acid structurally related to L-DOPA, microinjected into the caudal ventrolateral medulla (CVLM) and the rostral ventrolateral medulla (RVLM) shows cardiovascular actions similar to those of L-DOPA in anesthetized rats. When L-threo-DOPS was microinjected into CVLM, it produced dose-dependent (0.01-3 ng) depressor and bradycardic responses. D-threo-DOPS (3 ng) produced no effect. The responses to L-threo-DOPS (1 ng) were almost completely blocked by L-DOPA methyl ester (1 microg), a competitive antagonist for L-DOPA, supporting the existence of an L-threo-DOPS-sensitive recognition site for L-DOPA in CVLM. Microinjection of L-threo-DOPS into RVLM, however, showed no effect (0.001-100 ng), which contrasted with the cardiopressor action of L-DOPA applied in RVLM. In RVLM, there may exist an L-threo-DOPS-insensitive recognition site for L-DOPA.

Drastic reduction in antimicrobial activity by replacement of Orn residues with Lys in cyclized amphiphilic beta-structural model peptides.

Recent investigation have indicated that cyclic dodeca- and tetradecapeptides, cyclo(-Leu-Orn-Leu-Orn-D-Phe-Pro)2 (Orn-DLL-12) and cyclo(-Leu-Orn-Leu-Orn-Leu-D-Phe-Pro)2 (Orn-DLL-14), which are designed on the basis of a cyclic beta-structural antibiotic, gramicidin S (GS), inhibit the growth of Gram-positive and -negative bacteria with high potency [Ando, S., Nishikawa, H., Takiguchi, H., Lee, S. & Sugihara, G. (1993) Biochim. Biophys. Acta 1147, 42-49]. In this study we designed and synthesized two analogs, Lys-DLL-12 and Lys-DLL-14, in which four Orn residues in Orn-DLL-12 and Orn-DLL-14 were replaced by Lys residues, respectively, and investigated their interactions with model membranes in terms of CD and dye-leakage experiments, antimicrobial activity and lytic activity for human erythrocytes. Both peptides newly designed showed no antimicrobial activity and no lytic activity of erythrocytes. The present CD study showed that the presence of neutral liposomes and of acidic liposomes of natural or synthetic phospholipids results in no remarkable conformational difference between Orn-DLL-12/-14. The leakage experiment showed a clear relation between the antimicrobial activity and the leakage ability in acidic synthetic phospholipid liposomes but no correlation in acidic natural ones. The difference in hydrophobic and hydrophilic balance between Orn-DLL-12/14 and Lys-DLL-12/14 (derived from the increasing hydrophobicity due to an increase of four methylene units by the substitution of Lys for Orn) may be one of the important factors in the drastic decrease in activity.

[Evaluation of oxygen insufflation to non-ventilated lung during one-lung anesthesia].

To prevent hypoxemia during one-lung anesthesia, we have devised an oxygen insufflation machine which can insufflate oxygen (0.2-10 l.min-1) and apply CPAP (0-30 cmH2O) selectively to the non-ventilated lung. In all the 8 patients, arterial oxygen tension was maintained above 100 mmHg by using this machine, and was increased significantly from 76.2 +/- 11.2 mmHg (mean +/- SD) during one-lung anesthesia to 118.9 +/- 25.2 mmHg during the use of this machine. In conclusion, the machine prevents hypoxemia effectively during one-lung anesthesia without hindering surgical manipulations.

[Intraoperative plasmapheresis in patients undergoing CABG surgery; effect on intraoperative and postoperative homologous blood transfusion requirements].

To evaluate the effect of intraoperative plasmapheresis on intraoperative and postoperative homologous blood transfusion requirements, we assigned 89 patients undergoing primary CABG procedure to either the experimental group (plasmapheresis, n = 31, A group) or the control group (traditional method, n = 58, B group). All patients underwent hemodilution by withdrawal of autologous blood before cardiopulmonary bypass. In A group, the average volume withdrawn during plasmapheresis was approximately 948 ml (platelet rich plasma (PRP) and red blood cells). We removed an average of 751 ml of whole blood in B group. The percentage of patients without homologous blood transfusion in A group was 40% versus 32% in B group. The difference was not statistically significant. It was concluded that our method of plasmapheresis was effective in reducing homologous blood transfusion, but it was not more effective than the traditional hemodilution method.

[Reduction of the amount of perioperative blood transfusion by autotransfusion techniques in valvular heart surgery].

We used autotransfusion in valvular heart surgery and evaluated its effect on perioperative homologous blood requirements. Methods of autotransfusion we used were intraoperative blood salvage using Cell Saver 4 and retransfusion (IAT), postoperative autotransfusion of shed mediastinal blood (PAT), and hemodilutional autotransfusion (HAT). The patients undergoing valvular heart operations were divided into three groups; group 1 (control group), group 2 (using IAT and PAT group), and group 3 (using IAT, PAT, and HAT group). Perioperative homologous blood requirements significantly decreased in group 3 compared to group 1 and group 2. Operations without homologous blood transfusion significantly increased in number in group 3 compared with group 1. In conclusion, autotransfusions described above were useful blood conservation techniques in valvular heart surgery.

[The efficacy of blood conservation technique for coronary artery bypass graft surgery].

To evaluate the efficacy of blood conservation technique at our center, 144 patients undergoing primary coronary artery bypass grafting were studied between Jan. 1988, and Dec. 1990. Combined intraoperative and postoperative autotransfusion technique reduced the requirement of homologous blood to a half and 24% of the patients were without homologous transfusion. With more use of dilutional autotransfusion, 41% of the patients were without homologous transfusion. Intraoperative and postoperative autotransfusion technique is effective and dilutional autotransfusion is also a relatively effective method to reduce homologous transfusion.

Two separate neuronal populations of the rat subthalamic nucleus project to the basal ganglia and pedunculopontine tegmental region.

Employing a retrograde fluorescent double labeling technique, we compared the localization of subthalamic nucleus (STN) cells projecting to the striatum and nucleus tegmenti pedunculopontinus pars compacta (TPC), with that of STN cells sending axon collaterals to both the globus pallidus and substantia nigra in the rat. The STN-striatal projections were mostly the third branches of massive STN-pallidal and STN-nigral collateral projection neurons, whereas only very rarely did the STN-TPC projections contribute to these collateral projections. The TPC projecting STN cells, giving rise to an independent output of the nucleus, were located mainly in its thin lateral strip region. The STN may integrate the somatic motor information from various cortical/subcortical brain areas (including the motor cortex, striatum, globus pallidus, thalamus and TPC), and disperse it predominantly to the pallidal complex, substantia nigra and striatum by way of axon collaterals, and to a lesser degree to the TPC through separate fibers. Thus, the STN might be in a strategic position to exert a prominent control over the basal ganglia-related somatic motor functions.