ISSN:0003-3022    

出版商:OVID    

年代:1975

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

The effects of a new muscle relaxant, AH8165, on miniature endplate potential (MEPP) amplitude and frequency, endplate sensitivity to acetylcholine, and muscle twitch tension were studied in:vitroin the frog sartorius muscle. Nerve terminal effects were studied invivoin the cat soleus muscle and its ventral root fibers. AH8165 stimulates the nerve terminal, as evidenced by increased MEPP frequency and the appearance of post-drug repetitive activity. In the same concentration range at which MEPP frequency is increased, MEPP amplitude, endplate sensitivity to acetylcholine, and twitch tension are decreased. This suggests that AH8165 produces muscle relaxation by blocking postsynaptic cholinergic receptors.

ISSN:0003-3022    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

AH8165 was compared with other neuromuscular relaxants in anin-citrorat phrenic nerve—diaphragm preparation. Concentrations of 6-10 µg/ml AH8165 produced progressive decreases in strength of concentration. AH8165 was 0.1 times as potent asd-tubocurarine, and its effects were more rapidly reversed by washing. The times to recovery from 90 per cent blockade were the same for succinylcholine and AH8165, but the time to recovery from 50 per cent blockade was shorter for succinylcholine than for AH8165. Neostigmine reversed blockade induced by d-tubocurarine to 80 per cent of control, while it reversed comparable blockade induced by AH8165 to only 40 per cent of control. Doses of 0.5 to 2 µg AH8165 produced contracture and increased the force of contraction of the superfused chick biventer cervicis muscle preparation. Doses of 8 to 32 µg produced decreased contracture followed by diminution of the strength of contraction. The authors conclude that AH8165 in low concentrations has a depolarizing action, which is obscured by nondepolarizing effects in higher concentrations.

ISSN:0003-3022    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

Regional and cellular distribution of pentobarbital-2-14C in mouse brain was determined by frozen-section radioautographic methods. The mice were studied at the times of loss (WRL) and return (WRR) of withdrawal response following a single intravenous dose of either 40 or 50 mg/kg body weight. At WRL, grey matter areas had higher concentrations of pentobarbital-2-l4C than white matter. At WRR grey matter concentrations were not altered, but white matter areas were now similar to the grey. At WRL pentobarbital concentration was 55 per cent higher in large pyramidal cells in the parietal cortex than in surrounding neuropil. At WRL hippocampal pyramidal cell bodies (stratum pyramidalis) and glial cells in corpus callosum had pentobarbital levels similar to that of surrounding neuropil. Levels in the neuropil of these three areas were higher at WRR than at WRL. Lipid-rich compartments had higher pentobarbital concentrations at WRR than at WRL. The results suggest that return of consciousness after pentobarbital anesthesia is associated with intracerebral redistribution of pentobarbital even while there is continuing uptake into brain.

ISSN:0003-3022    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

Synaptosomes, or nerve-ending particles, were isolated from the cerebral cortices of young rats by homogenization, differential centrifugation, and density-gradient centrifugation. The sodium-potassium-activated adenosine triphosphatase enzyme system [(Na++ K+)-ATPase] of these particles is believed to representin vitrothe sodium-potassium pump of the nerve terminal. Suspensions of synaptosomes were equilibrated with air containing various concentrations of halothane and enflurane, as determined by gas chromatography. Clinical concentrations of the anesthetics had no effect on (Na++ K+)-ATPase activity. Fourteen per cent halothane and 14.8 per cent enflurane in gas phase resulted in 12 and 10 per cent inhibition, respectively, of (Na++ K+)-ATPase activity. These data confirm that interference with active cation transport by inhibition of neuronal (Na++ K+)-ATPase is not related to the mechanism of halothane or enflurane anesthesia.

ISSN:0003-3022    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

The actions of diethyl ether, enflurane, and isoflurane at the neuromuscular junction were examined in isolated guinea pig lumbrical muscles. These anesthetics depressed the ability of carbachol to depolarize the endplate region; this depression of depolarization did not show competitive kinetics. None of the anesthetics altered the affinity of the acetylcholine receptor ford-tubocurarine,i.e., the dissociation constant ofd-tubocurarine was unchanged. Since diethyl ether, enflurane, and isoflurane produced no observable alteration of the receptor, the antagonism of the drug-induced depolarization of the neuromuscular junction appears to be exerted at a stage subsequent to reaction with the receptor.

ISSN:0003-3022    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

Cardiovascular changes caused by intraperitoneal insufflation with CO2or N2O were measured in 15 mongrel dogs. Moderate progressive increases in intra-abdominal pressure (to 40 mm Hg) with either gas produced increases in mean arterial, right atrial, pleural, and femoral-vein pressures. Cardiac output and inferior vena caval flow were momentarily increased following the commencement of insufflation. However, both flows decreased precipitously as insufflation pressure was increased. At an intra-abdominal pressure of 40 mm Hg cardiac output and inferior vena caval flow were reduced more than 60 per cent in most cases. Peripheral resistance increased by approximately 200 per cent. Upon sudden release of abdominal pressure cardiac output and inferior vena caval flow increased but then returned to pre-insufflation values within seconds. Directly measured right atrial pressure increased with increasing insufflation pressure, but calculated transmural right atrial pressure decreased with the increase in intra-abdominal pressure. Insufflation with CO2. produced significant increases in PaCO2. However, cardiostimulatory effects due to elevated blood CO2. levels were not seen. The data from this study indicate that intraperitoneal insufflation produces serious hemodynamic alterations which are manifested by low cardiac output and elevated total peripheral resistance. In addition, directly measured right atrial pressure cannot be used clinically as an indicator of venous return to the heart since it reflects a composite of pleural and intra-abdominal insufflation pressures.

ISSN:0003-3022    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

The effects of fentanyl and droperidol on left ventricular performance were evaluated in the neurally intact dog right-heart-bypass preparation under conditions of constant cardiac output, arterial pressure, and heart rate. Fentanyl, .01 and .02 mg/kg body weight, and droperidol, 0.5 mg/kg, did not affect left ventricular performance. However, 1.0 mg/kg droperidol caused a significant (P<.05) increase in left ventricular end-diastolic pressure and a small decrease in maximum left ventricular dP/dt (.05<P<.10). No significant change in myocardial oxygen consumption was observed. This study indicates that large doses of droperidol may depress left ventricular performance and may account for a portion of the hypotension observed after its administration in man.

ISSN:0003-3022    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

Vastus lateralis muscle was excised from normal pigs and from pigs susceptible to malignant hyperthermia. Anesthesia consisted of diazepam, N2O:O2and a lidocaine field block. In the susceptible (MHS) pigs, respiratory control in mitochondria of excised muscle was normal, while electron transport was accelerated. Glutamate log Q3's and log Q4's were in inverse linear relationship to porcine weights. In the presence of glutamate, state 3 respiration was 3.5 times, and state 4 respiration 3.2 times, higher in MHS than in normal mitochondria (independent of weight or halothane dose). Thus, the MHS mitochondria were able to produce ATP more efficiently than normal mitochondria. Invitro, halothane inhibited glutamate Q3's and R.C.I.'s, slightly increased succinate Q3's and R.C.I.'s, had no significant effect on glutamate or succinate Q4's, and moderately lowered glutamate and succinate P/O ratios. These changes were similar to those observed in normal pigs. Calcium uptake into MHS mitochondria was markedly less than normal but was not significantly altered byin-vitrohalothane. These results suggest a mitochondrial membrane component for the defect of porcine malignant hyperthermia, since calcium is normally associated with the formation of the phospholiptd lattice of this membrane.

ISSN:0003-3022    

出版商:OVID    

年代:1975

数据来源: OVID