摘要:

The effects of fentanyl on airway smooth muscle are not known. In this report the authors compare the effects of fentanyl and morphine on isolated canine tracheal smooth muscle. The contractile response of tracheal muscle strips to transmural electrical stimulation was attenuated by fentanyl (≥3 × 10−9M) and morphine (≥3 × 10−7M) in a dose-dependent manner; the attenuation was partially reversed by naloxone. Contractions induced by acetylcholine, histamine, and serotonin were reduced by prior treatment with fentanyl (≥10−7M), but not morphine. The fentanyl-induced inhibition was not reversed by naloxone. In tracheal strips already contracted with acetylcholine, histamine, or serotonin, fentanyl produced relaxation, while, in contrast, morphine elicited a further contraction. In K+-contracted strips, fentanyl failed to produce relaxation. In tracheal strips sensitizedin vitroby rabbit antiserum to bovine serum albumin, the addition of antigen (bovine serum albumin) produced a transient contraction, which was suppressed by prior treatment with fentanyl or chlorpheniramine. It may be concluded that fentanyl and morphine interfere with the release of acetylcholine from cholinergic nerves innervating tracheal smooth muscle; the interference appears to be associated mainly with activation of opiate receptors. Fentanyl, but not morphine, appears to possess antimuscarinic, antihistaminergic H1, and antiserotonergic actions. This suggests that fentanyl may be preferable for use in asthmatic patients.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

The authors studied platelet kinetics in healthy dogs subjected to pulmonary-artery (Swan-Ganz) catheterization. Ten dogs with a mean weight of 11.0 ± 1.12 kg (SD) were equally divided into experimental and control groups. A fraction of platelets from each dog was harvested, labelled with51Cr, and reinfused. Daily blood samples for determinations of radioactivity and platelet count were obtained. From the third to fifth day after platelet labelling, experimental dogs underwent catheterization with Swan-Ganz catheters.During 48 hours following catheterization, platelet counts decreased 64.2 ± 15.2 per cent from baseline. There was no corresponding change in the control dogs. Calculated platelet survival times (based on decay in platelet radioactivity over time) were 102 ± 6.5 hours for the experimental group and 139.8 ± 16.3 hours for controls (P< 0.01). Postmortem examination of one sample dog demonstrated thrombus formation along the length of the catheter and in the pulmonary artery.Significant thrombocytopenia with decreased platelet survival is associated with the use of Swan-Ganz catheters in dogs. The mechanism has not been defined. This observation adds an important consideration to the interpretation of platelet kinetics observed in many pathologic states in animal models.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Contractile responses of rabbit aortic strips to transmural stimulation and to exogenously applied norepinephrine (NE), potassium chloride (KCl), and histamine were studied in the presence of lidocaine or its metabolites, monoethylglycinexylidide (MEGX) and glycinexylidide (GX). Lidocaine, 10−4and 5 × 10−4M, attenuated the contractile response to transmural stimulation, whereas MEGX, 2 × 10−5and 10−4M, potentiated, but 5 × 10−4M suppressed, the response. GX, 2 × 10−5to 5 × 10−4M, potentiated the response to transmural stimulation. The suppression induced by lidocaine and MEGX was not reversed by excess calcium, 2.2 and 4.4 mM, but was partially reversed by cocaine, 3 × 10−6M. Lidocaine, 5 × 10−4M, and MEGX, 2 × 10−3M, shifted the dose–response curve of NE to the right, whereas GX, 5 × 10−4M, shifted the curve to the left. The maximum tension developed by K+was attenuated by lidocaine, 5 × 10−4M, MEGX, 5 × 10−4and 2 × l0−3M, and GX, 2 × 10−3M. It may be concluded that lidocaine attenuates the response to stimulation of sympathetic nerves innervating the arterial wall by interfering with the release of NE. In contrast, the metabolites, MEGX and GX, potentiate the response, possibly by increasing the release of NE. MEGX in high concentrations appears to have the same mechanism of inhibitory action as does lidocaine.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

The effects of sodium nitroprusside (SNP) on the systemic and regional circulation, as well as on oxygen utilization, were studied in anesthetized dogs. A solution of SNP was infused intravenously to lower the blood pressure first to 75 per cent and then to 50 per cent of control. Seven of 15 dogs demonstrated resistance to SNP: SNP infusion rates ranging from 25 to 120 μg/kg/min were necessary in this group (resistant, or R, group) to bring blood pressure to 50 per cent of control, whereas less than 7 µg/kg/min SNP were needed to lower the blood pressure to 50 per cent of control in the other eight dogs, which were more sensitive to SNP (sensitive or S, group). In the control state, there was no apparent difference between the two groups in hemodynamic functions, oxygen transport, or oxygen utilization. In the R group, after blood pressure was lowered to 50 per cent of control, cardiac output increased to 150 per cent as a result of increased myocardial contractility, blood flows increased markedly in the myocardium (250 per cent) and brain (145 per cent) and decreased in the liver (hepatic artery, 40 per cent), kidney (50 per cent) and spleen (30 per cent), and myocardial oxygen consumption increased to 250 per cent of control. In the S group, corresponding values remained more or less constant throughout the period of hypotension. These findings may have significant implications in administering SNP to patients who are not responsive to SNP and who have hepatic or renal dysfunction, and/or coronary insufficiency.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

The cerebral response during halothane–succinylcholine anesthesia was examined in six malignant hyperthermia (MH)-susceptible and two normal swine. Cerebral and systemic values were determined for 50 min at 10-min intervals. These values were also determined in a susceptible animal given pentobarbital prior to and during halothane–succinylcholine anesthesia, and two susceptible animals in which MH was triggered by external warming. After the 50-min values had been obtained, biopsy specimens were taken from the brains of five animals. During MH induced by either drugs or warming, the cerebral metabolic rate for oxygen was similar to that determined prior to induction of MH and to that determined for the normal swine. While cerebral blood flow immediately increased in the six animals with drug-induced MH following the introduction of halothane, no such increase occurred either in the pentobarbital-treated animal or in the animals wherein MH was induced by external warming. In brain biopsy specimens from the susceptible animals, increases in lactate and lactate/pyruvate and a decrease in phosphocreatine were consistent with changes in systemic variables such as temperature and acid–base indices. When the influences of systemic and other variables are considered, the cerebral metabolic data suggest that the primary process(es) that generates MH does not occur in brain tissue, and that MH itself does not cause gross irreversible brain-cell damage or cerebral metabolic failure.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Deliberate hypotension has had variable success in decreasing blood losses and facilitating extensive surgical procedures. In this study, hemodynamic variables, catecholamines, plasma renin activity, and angiotensin II levels were studied in 11 patients undergoing operative correction of idiopathic scoliosis. Deliberate hypotension with mean arterial blood pressures ranging from 55 to 42 torr was provided with the ganglionic blocking agent, pentolinium tartrate, supplemented by beta blockade with propranolol during morphine–nitrous oxide anesthesia. Stroke volume index, systemic vascular resistance, and left ventricular stroke work index decreased 16, 19, and 40 per cent, respectively, with blood pressure reduction. Following the return to normal blood pressure, stroke volume index increased to a value 28 per cent greater than control, while systemic vascular resistance remained decreased. At this time left ventricular stroke work index increased slightly, but the increase was not statistically significant compared with control. The epinephrine level had risen from 59 to 270 pg/ml an hour after hypotension, probably secondary to infiltration of the skin prior to the surgical procedure. It had decreased to control levels by the end of the procedure. Norepinephrine and dopamine concentrations and plasma renin activity were unchanged. The angiotensin II level was significantly decreased, from 60 to 40 pg/ml, during deliberate hypotension. Blood loss correlated with left ventricular stroke work index, while changes in systemic vascular resistance and heart rate correlated well with changes in angiotensin II and plasma renin activity, respectively. The ability of ganglionic blockade and propranolol to inhibit the increases in catecholamines and angiotensin II during morphine–nitrous oxide anesthesia, hypotension, and surgical intervention may be of considerable importance.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

This study was aimed at providing a possible, testable explanation for the state of deep unconsciousness that ensues in an animal when anesthetic molecules reach a concentration of 3–5 moles per 100 moles of membrane lipid. Initially using liposomes as models for synaptic vesicles, it was confirmed that they accumulate and retain, catecholamines provided their interior aqueous compartment is more acid than the exterior. This is because bimolecular phospholipid membranes are very much more permeable to nonionized than to ionized solutes, including also H+and OH−. Thus, so long as a low intraliposomalpH is maintained, catecholamine bases remained charged and trapped. It is shown that anesthetics (butanol, hexanol, chloroform, and halothane) at activities (c/c0, where c and c0are the concentrations of the test and aqueous-saturated solutions, respectively) appropriate to general anesthesia (0.01–0.10) increase the proton permeability of liposomes, thus promoting the collapse of anypH gradient and indirectly facilitating the rapid outward permeation of the now uncharged, membrane-permeable transmitter substances. Synaptic vesicles from rat brain also accumulate catecholamines in response to apH gradient, and anesthetics over a range of general and local concentrations release them. On the basis of these results, it is suggested that one mode of anesthetic action may be the release of catecholamines from synaptic storage vesicles, initially into the nerve terminal cytosol, leading to depressed neurotransmission, perhaps involving both inhibitory and excitatory pathways.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

This study was done to demonstrate the validity of the log-probit method of analyzing dose–response data and to test the accuracy of the incremental dose method for generating dose–response data for pancuronium andd-tubocurarine. During balanced general anesthesia, cumulative dose–response data were obtained from ten patients each for pancuronium andd-tubocurarine. Dose–response data were also obtained using a single bolus injection method in 46 patients given pancuronium and 27 patients givend-tubocurarine. Evoked thumb adduction response was measured using an FT-10 force-displacement transducer and recorded on a Grass®-7 polygraph. Dose–response data were plotted on log-probit paper and analyzed by the Litchfield-Wilcoxon approximation method to determine mean ED50and ED95for each muscle relaxant. The dose–response data were also plotted on arithmetic scales and analyzed by the linear regression method to determine ED50and ED95. These results were compared with those obtained by use of the log-probit method.The validity of the incremental dose method of obtaining dose–response curves was determined by comparison with the dose–response curves obtained using the conventional single bolus injection method. For each neuromuscular relaxant studied, the mean dose–response curve obtained by the cumulative dose method was not statistically significantly different from the bolus method dose–response curve. Comparing methods of analysis, the log-probit method yields results that are statistically not different from those obtained by use of conventional linear regression analysis.The log-probit plot is a simple, accurate, appropriate approach for analyzing neuromuscular relaxant dose–response data. The log-probit curve yields results that are not statistically significantly different from those of the linear regression method, and is a better fit to the data at the clinically important extremes (85–99 per cent) of the response scale. For pancuronium andd-tubocurarine, the incremental dose method is efficient and accurate for generating dose–response curves.

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1980

数据来源: OVID