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PubMed1982

Interaction of spin-labeled local anesthetics with the sodium channel of squid axon membranes.

The effects of spin-labeled local anesthetics on sodium currents of internally perfused squid axons were studied using the voltage-clamp technique. Internal application (10 mum) of the most potent spin-labeled local anesthetic used in this study produced a small initial block of sodium currents. However, after sixty repetitive pulses (to + 80 mV) given at 1 Hz, the sodium currents were drastically reduced. In addition to this frequency-dependent phenomenon, the anesthetic effect on the sodium currents was also sensitive to the voltage of the pulses. Both the frequency- and voltage-dependent properties remained intact after removal of sodium inactivation with pronase. The recovery of sodium currents from this frequency-dependent anesthetic effect followed a single exponential curve with a surprisingly long time constant of about 10 min. Such a long recovery time, which is longer than any known sodium inactivation process, led us to suggest that the recovery process represents the dissociation of drug molecules from their binding sites. We have also found that increasing hydrophobic character of the homologues series of spin-labeled local anesthetics enhances the frequency- and voltage-dependent block of sodium currents. This effect strongly suggests that hydrophobic interaction is an integral component of the binding site. These probes with their selective effects on the sodium currents, are expected to be highly useful in studying the molecular structure of the sodium channels.

Action Potentials↗

PubMed1982

Effects of local anesthetics on phospholipid topology and dopamine uptake and release in rat brain synaptosomes.

The effects of local anesthetics on the topology of aminophospholipids and on the release and uptake of dopamine in rat brain synaptosomes have been examined. A metabolically intact preparation of synaptosomes was prepared which maintains amino-phospholipid asymmetry and the capacity for sodium-driven uptake and depolarization-dependent release of dopamine. Incubation of synaptosomes with local anesthetics at 37 degrees C induced perturbations in the topology of aminophospholipids as determined by their reactivities to the covalent probe trinitrobenzenesulfonic acid. The reaction of trinitrobenzenesulfonate with phosphatidylethanolamine and phosphatidylserine was inhibited 10-20% by low concentrations of tetracaine (1-100 muM) and enhanced by high concentrations (0.3-1.0 mM). Other local anesthetics showed a similar biphasic effect with a potency order of dibucaine greater than tetracaine greater than lidocaine greater than or equal to procaine. K+-stimulated, Ca2+-dependent release of [3H]dopamine was inhibited significantly at low concentrations of tetracaine (1-10 muM) but enhanced at higher concentrations (0.1-1.0 mM). Dibucaine and procaine had a similar biphasic effect on the dopamine release. For each of the local anesthetics tested, the inhibition of the reaction of phosphatidylethanolamine and phosphatidylserine with trinitrobenzenesulfonate occurred at concentrations which were shown also to inhibit the release of [3H]dopamine. Local anesthetics were shown to inhibit uptake of [3H )dopamine with a potency order which reflects their potency in producing anesthesia. The inhibition of dopamine uptake by dibucaine, tetracaine, lidocaine, or procaine was characterized by inhibitory constants (KI) of 1.8 +/- 0.4 muM, 27 +/- 5 muM, 190 muM and 0.5 mM, respectively.

Anesthetics, Local↗

PubMed2001

The WAND local anesthetic delivery system: a more pleasant experience for anal anesthesia.

PURPOSE: The WAND is a computer-controlled local anesthetic delivery system. Its use has been proven to be more comfortable for dental patients. The purpose of this study is to explore its applicability to anal procedures. Our hypothesis is that the WAND will provide greater comfort during anesthesia delivery while achieving the same anesthetic effect as traditional syringe technique. METHODS: Twenty patients with painless anal pathology were randomized to receive anal anesthesia using either the WAND or traditional syringe technique to a randomly selected half of the anoderm (right or left). The opposite side was then anesthetized by the alternate method, allowing patients to act as their own control. Objective and subjective pain scores were obtained from the patient after each mode of delivery. An independent observer interpreted the patient's tolerance by giving a subjective pain score. The volume of anesthetic used was recorded. Adequacy of anesthesia was tested by a pinch test. RESULTS: Sixteen (80 percent) of the 20 patients preferred the use of the WAND. Objective and subjective pain scores per the patients and subjective pain scores per the observer were significantly lower for the WAND than for traditional syringe technique (P < 0.05). The mean volume of local anesthetic used with the WAND was 1.7 ml compared with 3.2 ml for traditional syringe technique (P < 0.005). Anesthesia achieved with the WAND was as good as that achieved with traditional syringe technique when the pinch test was used. CONCLUSION: The WAND is as effective as the traditional syringe technique in the delivery of anal anesthesia while providing a more comfortable experience for the patient.

Adult↗

PubMed1986

Dedicated monitoring of anesthetic and respiratory gases by Raman scattering.

The monitoring of respiratory and anesthetic gases in the operating room is important for patient safety. This study measured the accuracy and response time of a multiple-gas monitoring instrument that uses Raman light scattering. Measurements of oxygen, carbon dioxide, nitrogen, nitrous oxide, halothane, enflurane, and isoflurane concentrations were compared with a gas mixer standard and with measurements made with an infrared anesthetic agent analyzer. Correlation coefficients were all greater than 0.999, and probable errors were less than 0.43 vol% for the gases and less than 0.03 vol% for the volatile anesthetics. Response time was 67 ms with a sample flow rate of 150 ml/min. There was some signal overlap between nitrogen and nitrous oxide and between the volatile anesthetic agents. Such overlap can be compensated for by linear matrix analysis. The Raman instrument promises a monitoring capability equivalent to the mass spectrometer and should prove attractive for the monitoring of respiratory and anesthetic gases in the operating room.

Air↗

PubMed1999

Saline volume and local anesthetic concentration modify the spread of epidural anesthesia.

PURPOSE: To examine the effects of the volume of saline and the concentration of local anesthetic on the quality of anesthetic level. METHODS: One hundred and fifty two patients received thoracic epidural anesthesia were allocated into two groups; mepivacaine 1% (75 patients) and 1.5% (77 patients). Each group was randomly divided into three subgroups depending on epidural saline volumes of 1 ml, 5 ml, or 10 ml. Fifteen minutes after the injection of 10 ml mepivacaine, the dermatome levels of hypesthesia to cold and pinprick were determined by an individual blinded to the saline volume. RESULTS: The number of spinal segments with hypesthesia to cold in the three subgroups in the mepivacaine 1% group were 12.5 [6-20], 13 [8.5-20.5] and 12.5 [6.5-22], respectively (median [range]). The segments in the mepivacaine 1.5% group were 12 [7-18.5], 14 [8.5-19]* and 15 [6-23]*, respectively (*P < 0.05 vs 1-ml group). The number of spinal segments with hypesthesia for pinprick in the three subgroups in the 1% mepivacaine group were 10.5 [2-22], 10.5 [4-17] and 11 [4-19], respectively. The segments in the mepivacaine 1.5% group were 12 [7.5-16], 12 [7.5-17] and 11.5 [5-22.5], respectively. Saline volume did not alter the anesthetic level of the mepivacaine 1%, although it did affect the anesthetic spread of the mepivacaine 1.5%. In both groups, a differential nerve block was elicited in the 5 ml and 10 ml saline subgroups. CONCLUSION: When a large volume of saline is administered prior to local anesthetic, more differential blockade and a greater extent of anesthesia may be elicited.

Aged↗

PubMed1999

Saline-anesthetic interval and the spread of epidural anesthesia.

PURPOSE: To examine the effect of modifying the interval between administration of saline used during the loss of resistance (LOR) method and local anesthetic on epidural anesthetic level and its quality. METHODS: Seventy-three patients who received thoracic epidural anesthesia were randomly allocated into three groups; the 2, 5 and 10 min groups, according to the interval between the administration of saline and 8 ml mepivacaine 1.5%. Fifteen minutes after the mepivacaine injection, the dermatome level of hypesthesia was determined by an individual blinded to the interval. RESULTS: When the saline-anesthetic interval was prolonged, the hypesthetic levels for coldness and pinprick were decreased. The number of spinal segments with hypesthesia for coldness were 15 [12-20]#, 12.5 [10.5-22.5]## and 10.5 [6.5-15.5]### in the 2, 5 and 10 min groups, respectively (median [range], # P < 0.05 vs the 5 min group, ## P < 0.05 vs the 10 min group, ### P < 0.05 vs the 2 min group). The number of spinal segments with hypesthesia for pinprick were 13.5 [11-18]#, 11 [7.5-20.5]## and 10 [5.5-13]### in the 2, 5 and 10 min groups, respectively. There were differences in all groups between the number of segments with hypesthesia for coldness and pinprick elicited. CONCLUSION: The interval between the administration of saline and local anesthetic alters the anesthetic level and quality of epidural analgesia.

Abdomen↗

PubMed2002

Calcium channels--basic aspects of their structure, function and gene encoding; anesthetic action on the channels--a review.

PURPOSE: To review recent findings concerning Ca(2+) channel subtype/structure/function from electrophysiological and molecular biological studies and to explain Ca(2+) channel diseases and the actions of anesthetics on Ca(2+) channels. SOURCE: The information was obtained from articles published recently and from our published work. PRINCIPAL FINDINGS: Voltage-dependent Ca(2+) channels serve as one of the important mechanisms for Ca(2+) influx into the cells, enabling the regulation of intracellular concentration of free Ca(2+). Recent advances both in electrophysiology and in molecular biology have made it possible to observe channel activity directly and to investigate channel functions at molecular levels. The Ca(2+) channel can be divided into subtypes according to electrophysiological characteristics, and each subtype has its own gene. The L-type Ca(2+) channel is the target of a large number of clinically important drugs, especially dihydropyridines, and binding sites of Ca(2+) antagonists have been clarified. The effects of various kinds of anesthetics in a variety of cell types have been demonstrated, and some clinical effects of anesthetics can be explained by the effects on Ca(2+) channels. It has recently become apparent that some hereditary diseases such as hypokalemic periodic paralysis result from calcium channelopathies. CONCLUSION: Recent advances both in electrophysiology and in molecular biology have made it possible to clarify the Ca(2+) channel structures, functions, genes, and the anesthetic actions on the channels in detail. The effects of anesthetics on the Ca(2+) channels either of patients with hereditary channelopathies or using gene mutation techniques are left to be discovered.

Anesthetics↗

PubMed2006

Preparation of the Dräger Primus anesthetic machine for malignant hyperthermia-susceptible patients.

PURPOSE: Preparation of anesthesia machines for patients who are susceptible to malignant hyperthermia includes flushing the machine with vapour-free fresh gas to washout residual anesthetic agents. To establish guidelines for the preparation of the Dräger Primus machine, we compared the washout profiles for isoflurane and sevoflurane in the Dräger Primus and Ohmeda Excel 210 anesthesia machines. TECHNICAL FEATURES: The machines were primed with 1.5% isoflurane or 2.5% sevoflurane. Fresh gas flow (FGF) was set at 10 L.min(-1) during the early washout phase, and subsequently reduced to 3 L.min(-1) during the late washout phase. A Miran ambient air analyzer measured the anesthetic concentration every minute during washout until a concentration of 5 ppm was achieved in the inspiratory limb of the circle circuit. We found that at a FGF of 10 L.min(-1), maximum washout times for isoflurane and sevoflurane in the Primus, 70 and 74 min, respectively, were approximately tenfold greater than for isoflurane in the Excel 210 (7.0 min). Increasing the FGF to 18 L.min(-1) decreased the washout time for isoflurane in the Primus, only moderately, to 52 min. We observed a threefold increase in anesthetic concentration in the Primus during the late washout phase. CONCLUSION: We conclude that the Primus must be flushed for at least 70 min to decrease the anesthetic concentration to 5 ppm when using a FGF of 10 L.min(-1). We recommend maintaining a FGF of 10 L.min(-1) for the duration of anesthesia in order to prevent the rebound increase in anesthetic concentration in the FGF.

Anesthesiology↗

PubMed2006

The effects of volatile anesthetics on cardiac ischemic complications and mortality in CABG: a meta-analysis.

PURPOSE: Coronary artery bypass graft surgery (CABG) is associated with cardiac complications, including ischemia, acute myocardial infarction (AMI), and death. Volatile anesthetics have been shown to have a preconditioning-like effect. This systematic review assesses the effects of volatile anesthetics on cardiac ischemic complications and morbidity after CABG. METHODS: Data were obtained, without language restriction, from searches of MEDLINE, Science Citation Index, PubMed, and reference lists. We included only prospective randomized controlled trials evaluating volatile anesthetics during CABG. Two reviewers independently abstracted data on myocardial ischemia, acute myocardial infarction (AMI), and death. Treatment effects were calculated as odds ratio (OR) with 95% confidence intervals (CI) for binary data, and weighted mean difference (WMD) with 95% CI for continuous data. PRINCIPAL FINDINGS: Thirty-two studies (2,841 patients) were included. In comparison with iv anesthesia, volatile anesthetics were associated with reduced all-cause mortality (OR, 0.65; 95% CI, 0.36-1.18; P = 0.16). Enflurane was associated with increased AMI (OR, 1.34; 95% CI, 0.68-2.64; P = 0.40), whereas sevoflurane and desflurane reduced cardiac troponin I (cTnI) at six hours, 12 hr, 24 hr [WMD, -1.45; 95% CI (-1.73, -1.16); P < 0.00001], and 48 hr after operation. CONCLUSION: This meta-analysis demonstrates sevoflurane and desflurane reduce the postoperative rise in cTnI. Sevoflurane-mediated reduction in cardiac troponin was associated with improved long-term outcomes in one study. This meta-analysis was not able to show that these positive effects on troponin were translated into improved clinical outcomes. Well-designed large randomized control trials are needed to further elucidate the differential cardio-protective effects of volatile anesthetics.

Anesthetics, Inhalation↗

PubMed2006

Documentation on the anesthetic record: Correlation with clinically important variables.

PURPOSE: A survey was undertaken at a single Academic Health Sciences Centre to document the opinions of anesthesiologists regarding what variables are important to document on the anesthetic record. A subsequent chart review of anesthetic records was undertaken to determine the extent to which these anesthesiologists record the variables they consider important. METHODS: A survey form was mailed to all practicing staff anesthesiologists at the four adult McGill University affiliated hospitals. Anesthesiologists were asked to rank 23 preoperative and 33 intraoperative variables on a scale from 1-5: (1 = essential; 2 = important; 3 = useful; 4 = not important; 5 = excessive information). All variables considered by consensus < or = 2 (important to essential) were then assessed as to whether they were recorded on 60 charts randomly selected from each of the four teaching hospitals. Only anesthetic records completed by staff anesthesiologists were evaluated. RESULTS: Ninety percent (47/52) of survey forms were completed and returned. Preoperative variables considered most important to document included examination of the patient's airway and allergy status. Intraoperative variables considered most important for documentation were the patient's vital signs. The only variable to have been recorded on all the anesthetic records was the anesthesiologist's name. The allergy status was the most recorded preoperative variable (84% of charts). The recording rates of intraoperative variables ranged from 100% (anesthesiologist's name, start time of anesthesia) to 24% (estimated blood loss). CONCLUSION: McGill anesthesiologists consider many preoperative and intraoperative variables to be important to document on the anesthetic record. However, subsequent chart review indicated that many of these variables are recorded inconsistently. The transmission of anesthesia-related medical information might be improved if anesthesiologists recorded more consistently information they consider to be important.

Adult↗

PubMed2001

Production of compound A under low-flow anesthesia is affected by type of anesthetic machine.

PURPOSE: The purpose was to compare the concentrations of compound A in inspired gas breathed by patients produced by different types of anesthetic machines under prolonged sevoflurane low-flow anesthesia. METHODS: The anesthetic machines tested were Excel 210 SE (Datex-Ohmeda, Louisville, CO), Cicero (Dräger, Lübeck, Germany), and AS/3 ADU (Datex-Ohmeda, Louisville, CO). Anesthesia expected to last more than four hours was maintained with 2.0% sevoflurane and nitrous oxide (0.5 L x min(-1))/oxygen (0.5 L x min(-1)). The concentrations of compound A, obtained from the inspiratory limb of the circle system, were measured using a gas chromatograph. RESULTS: When Excel and Cicero were used, concentrations of compound A increased steadily from the baseline values to 28 and 29 (mean) ppm, respectively, at two hours after exposure to sevoflurane and became constant. There was no significant difference between the concentrations of compound A produced by these anesthetic machines. In contrast, the new anesthetic machine AS/3 was associated with lower concentrations of compound A (6 ppm at one hour, P <0.05 compared with Excel and Cicero), and the concentration did not change significantly thereafter. CONCLUSION: In spite of the use of a conventional carbon dioxide (CO2) absorbent with strong bases, the anesthetic machine AS/3 with a small volume of canister/soda lime (900 ml/700 ml) produced lower concentrations of compound A than those produced by the other machines.

Anesthesia, Inhalation↗

PubMed2001

Role of the dopamine transporter and the sodium channel in the cocaine-like discriminative stimulus effects of local anesthetics in rats.

RATIONALE: Local anesthetics bind to the dopamine transporter (DAT), inhibit dopamine (DA) uptake and have been reported to have cocaine-like discriminative stimulus effects. The hypothesis of the present study was that affinity at the DAT and potency as a DA uptake blocker determines potency as a cocaine-like discriminative stimulus among local anesthetics, and maximum DA uptake inhibition determines maximum cocaine-like discriminative stimulus effects. OBJECTIVES: Cocaine-like discriminative potency was compared to DAT affinity and DA uptake inhibition potency, and maximum cocaine-like discriminative stimulus effects were compared to maximum DA uptake inhibition for procaine, chloroprocaine, dimethocaine, tetracaine and lidocaine. METHODS: Discriminative stimulus effects were determined in two groups of rats using 10 mg/kg and 3.0 mg/kg cocaine training doses. DAT affinity and DA uptake inhibition effects were determined in vitro in rat caudate nucleus tissue. Additionally, sodium channel affinity was determined in rat frontal cortex tissue. RESULTS: In the 10 mg/kg group, none of the local anesthetics fully substituted for cocaine and all decreased response rate. Rate decreasing potencies were positively correlated with sodium channel affinities. In the low training dose group, all the local anesthetics except tetracaine substituted fully for cocaine. Discriminative potencies were positively correlated with sodium channel affinities. Maximum DA uptake inhibition did not adequately predict maximum discriminative stimulus effects. CONCLUSIONS: Cocaine-like discriminative stimulus effects of local anesthetics were more prominent at a low than at a high training dose of cocaine. Sodium channels seem to have a direct influence on discriminative effects at low cocaine doses, whereas they have an indirect influence on discriminative effects at high cocaine doses by decreasing response rates.

Anesthetics, Local↗

PubMed2002

Increased inspiratory pressure for reduction of atelectasis in children anesthetized for CT scan.

BACKGROUND: Atelectasis is more frequent and more severe in children anesthetized for CT scan than it is in children sedated for CT scan. OBJECTIVE: To determine the effect of increased inspiratory pressure on atelectasis during chest CT in anesthetized children. MATERIALS AND METHODS: Atelectasis on chest CT was assessed by two observers in three groups of patients. Group A comprised 13 children (26 lungs) anesthetized at inspiratory pressures up to and including 25 cm H2O. Group B included 11 children anesthetized at inspiratory pressures > or =30 cm H2O. Group C included 8 children under deep sedation. RESULTS: Atelectasis was significantly more severe in group A than in groups B and C. There was no significant difference between groups B and C. CONCLUSION: An inspiratory pressure of 30 cm H2O is recommended for children anesthetized for CT scan of the chest.

Anesthetics, General↗

PubMed1998

Tetrodotoxin: anesthetic activity in the de-epithelialized cornea.

BACKGROUND: Tetrodotoxin (TTX) binds with high affinity to sodium channels and produces local anesthesia. We investigated whether TTX is an effective, long-acting corneal anesthetic in rabbits. METHODS: After mechanical debridement of the central corneal epithelium, topical TTX (1 mM, 0.1 mM, or 0.01 mM) was applied to one eye each of 18 New Zealand White rabbits. The fellow eye of each rabbit was treated with control vehicle. Blink response to a mechanical stimulus was assessed. Blink response was also assessed every 3 h for 30 h in 6 rabbits treated with 1 mM TTX administered every 6 h. In a separate group of 12 rabbits with central epithelial debridement, the rate of epithelial healing was compared between animals treated with topical 1.0 mM TTX and animals receiving no treatment. RESULTS: After 4 h, eyes treated with 1.0 mM and 0.1 mM TTX were anesthetic. At 6 h, five of six rabbit eyes treated with 1.0 mM TTX were still partially anesthetic. By 8 h, the mean anesthesia score for 1.0 mM TTX was approaching normal. With multiple dosing, all six rabbit eyes remained anesthetic for the duration of the experiment. There was no significant difference in the rate of re-epithelialization between eyes treated with TTX and untreated controls. There was no evidence of systemic or local toxicity from topical TTX. CONCLUSION: In a rabbit model, TTX is a long-acting topical anesthetic that retains its effectiveness when administered repeatedly over 24 h and does not inhibit epithelial healing. It may have application in management of pain after photorefractive keratectomy.

Administration, Topical↗

PubMed2000

Effects of galanin(1-16) on pancreatic secretion in anesthetized and conscious rats.

Galanin, a 29-amino acid peptide, has been demonstrated in pancreatic nerve endings and found to inhibit insulin release in the rat. However, the data available concerning its effects on exocrine pancreatic secretion are contradictory. The aim of the present study was to evaluate the effects of a synthetic porcine galanin sequence, Gal(1-16), on stimulated pancreatic secretion in hyperglycemic anesthetized and conscious rats. Male Wistar rats were anesthetized and surgically prepared with pancreatic and femoral vein catheters. In anesthetized animals, the pancreatic secretion was continuously stimulated with 150 ng cholecystokinin octapeptide (CCK-8)/kg body weight per 30 min, dissolved in saline or 10% glucose. Synthetic Gal(1-16) (0.3 or 1 nmol/kg per h) was infused over a 60-min period. In conscious rats, 1, 3, or 10 nmol Gal(1-16)/kg per h was administered in a continuous saline or 10% glucose infusion over a 30-min period. The pancreatic secretory volume and protein output were determined in 30-min samples in both models. In anesthetized rats, 0.3 nmol Gal(1-16)/kg per h did not modify pancreatic secretion during CCK-8 stimulation. However, both the pancreatic secretory volume and the protein output were significantly inhibited compared with the basal levels by 1 nmol Gal(1-16)/kg per h. The inhibitory effect of Gal(1-16) on pancreatic secretion was more marked with CCK-8/glucose (53.9%) than with CCK-8/saline stimulation (20.1%). In conscious rats, significant inhibitory effects of 1 nmol Gal(1-16)/kg per h in saline were observed (18%). During glucose infusion, a dose-dependent inhibition of 1, 3, and 10 nmol Gal(1-16)/kg per h on pancreatic secretory volume and protein output (35% inhibition at 1 nmol/kg per h) was observed. In conclusion, the inhibitory effect of Gal(1-16) on exogenous and endogenous CCK-stimulated pancreatic secretion was found to be more potent in the presence of glucose both in anesthetized and in conscious rats. These results may suggest an indirect (insulin-mediated) inhibitory effect of porcine Gal(1-16) on pancreatic secretion in the rat.

Anesthesia↗

PubMed1999

Volatile anesthetic action on muscle Ca2+ homeostasis.

It is proposed that volatile anesthetics act through the modification of Ca2+ homeostasis in excitable cells. To test this hypothesis, cardiac and skeletal muscles were used as models to examine Ca2+ response, and Ca2+ regulatory and delivery mechanisms. I found that halothane did not alter Ca2+ binding to cardiac troponin C. However, halothane and isoflurane reversibly decreased the Ca2+ affinity of calmodulin at low anesthetic concentration, and irreversibly increased the Ca2+ affinity of calmodulin at high anesthetic concentration. The volatile anesthetics also increased the permeability of light fraction of sarcoplasmic reticulum (SR) to Ca2+. I conclude that volatile anesthetics alter calcium homeostasis in cardiac and skeletal muscles. This work was in part performed in collaboration with Giovanni Salviati and the author benefited from Salviati's work in similar areas.

Anesthetics, Inhalation↗

PubMed1980

Pressure-anesthetic antagonism on the phase separation of non-ionic surfactant micelles.

An aqueous solution of non-ionic surfactants becomes suddenly turbid when heated to a critical temperature, known as the cloud point, and concomitantly expands the volume. The volume expansion is caused by release of structured water molecules from the hydrophilic polyoxyethyelene moieties. Inhalation anesthetics decreased the cloud-point temperature of hexaoxyethylene dodecyl ether micelles. The concentrations of methoxyflurane, halothane and enflurane causing a 1 degree C depression of the cloud-point temperature were 0.51, 0.71 and 0.78 mmolal, respectively. Hydrostatic pressure increased the cloud-point temperature in the absence and presence of the anesthetics. The change of the apparent molal volume at the cloud point was estimated to be 2.2 cm3/mol in the absence of anesthetics. This value decreased in the presence of the anesthetics, dose dependently. The results indicate that the anesthetics favor dehydration of the hydrophilic surface of the non-ionic surfactant micelles.

Anesthetics↗

PubMed1981

Correlation of general anesthetic potency with solubility in membranes.

Recently (Franks, N.P. and Lieb, W.R. (1978) Nature 274, 339-342) it has been claimed that the traditional correlation between anesthetic potency and vegetable oil solubility breaks down when the alkanols are compared to other volatile anesthetics. Lately, however, new information on the partitioning of anesthetics into lipid bilayers has become available. In this report the potency of twenty-one structurally diverse anesthetic agents is shown to correlate well with their ability to partition into phosphatidylcholine bilayers. Thus the original Meyer-Overton oil solubility hypothesis accommodates a wider range of anesthetics, including alkanols, volatile and gaseous agents, and barbiturates, when lipid bilayer solubility is substituted for oil solubility.

Anesthesia, General↗