Nrf2 Antioxidative System is Involved in Cytochrome P450 Gene Expression and Activity: A Delay in Pentobarbital Metabolism in Nrf2-Deficient Mice.

NF-E2-related factor 2 (Nrf2) is a transcriptional regulator of biologic defense proteins, such as antioxidant proteins and phase II detoxification enzymes. Cytochrome P450 (P450) enzymes have been shown to regulate phase I metabolism of various drugs and are partially regulated by Nrf2; however, the influence of Nrf2 on drug pharmacokinetics is not known. Here, we showed that Nrf2 depletion prolonged the effect of pentobarbital, a sleep-promoting drug. Pretreatment with phenobarbital, a P450 inducer, shortens the sleeping time associated with pentobarbital-induced sedation in wild-type (WT) mice; however, this effect was not observed in Nrf2-/- mice. Furthermore, the blood pentobarbital concentration was higher in Nrf2-/- mice than in WT mice at 30-60 minutes, and the phenobarbital-induced enhancement of its clearance was attenuated in Nrf2-/- mice compared with WT mice. Total P450 content was decreased in Nrf2-/- mouse livers, and the phenobarbital-induced increase in P450 content was lower in Nrf2-/- mice than WT mice. Cyp1a2, Cyp2a5, Cyp2c29, and Cyp2e1 gene expression levels under physiologic conditions and Cyp1a2, Cyp2a5, and Cyp2b10 gene expression levels under phenobarbital-treated conditions were lower in Nrf2-/- mice compared with WT mice. Additionally, pentobarbital metabolism in liver microsomes was attenuated by Nrf2 depletion. Taken together, these findings suggested that Nrf2 influenced pentobarbital pharmacokinetics through the regulation of drug metabolism and P450 gene expression. Thus, Nrf2-mediated regulation of P450 may contribute to the biologic defense against increased reactive oxygen species production. SIGNIFICANCE STATEMENT: NF-E2-related factor 2 (Nrf2) plays a critical role in the cellular defense against oxidative stress. Nrf2-/- mice with reduced ability to eliminate reactive oxygen species (ROS) showed a significant delay in emergence from pentobarbital-induced sleep, which was associated with decreased P450 activities and gene expression. Our findings provide that Nrf2 dysfunction or ROS that exceed a threshold level of the eliminating ability of the Nrf2 system may reduce P450 activity.

Localized anesthesia of a specific brain region using ultrasound-responsive barbiturate nanodroplets.

Background: Targeted neuromodulation is a valuable technique for the study and treatment of the brain. Using focused ultrasound to target the local delivery of anesthetics in the brain offers a safe and reproducible option for suppressing neuronal activity. Objective: To develop a potential new tool for localized neuromodulation through the triggered release of pentobarbital from ultrasound-responsive nanodroplets. Method: The commercial microbubble contrast agent, Definity, was filled with decafluorobutane gas and loaded with a lipophilic anesthetic drug, before being condensed into liquid-filled nanodroplets of 210 ± 80 nm. Focused ultrasound at 0.58 MHz was found to convert nanodroplets into microbubbles, simultaneously releasing the drug and inducing local anesthesia in the motor cortex of rats (n=8). Results: Behavioral analysis indicated a 19.1 ± 13% motor deficit on the contralateral side of treated animals, assessed through the cylinder test and gait analysis, illustrating successful local anesthesia, without compromising the blood-brain barrier. Conclusion: Pentobarbital-loaded decafluorobutane-core Definity-based nanodroplets are a potential agent for ultrasound-triggered and targeted neuromodulation.

Stability of pentobarbital in soil.

Intravenous injection of barbiturates, particularly pentobarbital (5-ethyl-5-pentan-2-yl-1,3-diazinane-2,4,5-trione), is a widely used method to euthanize large animals such as horses. However, one concern with this method is the fate of pentobarbital after the disposal of the carcass. As tissues decompose, pentobarbital may leach into the soil and from there migrate to groundwater. A method using methanol extraction, solid phase concentration, and liquid chromatography (LC/MS) has been developed to measure pentobarbital in soils. Recovery of pentobarbital from soil averaged approximately 85% from different soil types including topsoil, potting soil, sand, stall sweepings, and loam. The method was capable of detecting pentobarbital levels of 0.1 ppm. A calibration curve was constructed with a linear range of 1 ppm to 100 ppm. The limit of quantification was 0.5 ppm. The rate of degradation of pentobarbital in sand, topsoil, and potting soil was measured over a 17-week period. At the end of week 17, approximately 17% of the pentobarbital remained in the sand, 19% remained in the topsoil, and 10% remained in the potting soil. While there was a significant decrease in the pentobarbital recovered from the soil, there were still detectable amounts of pentobarbital present in the soil after 17 weeks. To determine the importance of bacterial degradation, the three soil types were autoclaved before addition of pentobarbital. After autoclaving, no degradation of pentobarbital was observed in sand and one topsoil sample, while there was no difference in the degradation of pentobarbital in autoclaved potting soil versus potting soil that had not undergone autoclaving.

Pentobarbital Removal During Continuous Venovenous Hemofiltration: Case Report and Review of the Literature.

BACKGROUND:: Renal replacement therapy may enhance the elimination of barbiturates. Pentobarbital clearance during continuous venovenous hemofiltration (CVVH) has not been described previously. We report a patient case involving the measurement of serial pentobarbital levels during CVVH and review relevant literature characterizing extracorporeal pentobarbital elimination. METHODS:: The following is a retrospective report of a previously healthy 26-year-old woman who sustained a severe traumatic brain injury (TBI) and required administration of pentobarbital on hospital day 0 for intracranial pressure (ICP) control. Given concern for interference with the patient's ongoing neurologic assessments, pentobarbital was discontinued on hospital day 4. The patient's hospital course was complicated by acute kidney injury (AKI), requiring initiation of CVVH on hospital day 5. Daily serum pentobarbital levels were obtained during CVVH. RESULTS:: While on CVVH, the patient's estimated pentobarbital clearance ranged from 6 to 44 mL/min and the elimination half-life ranged from 17.7 to 65.9 hours. Based on reductions in pentobarbital clearance during CVVH interruption, the elimination of drug was dependent upon extracorporeal removal in this patient. CVVH facilitated pentobarbital elimination in a manner approaching endogenous clearance in healthy individuals. CONCLUSION:: We report clinically significant pentobarbital removal by CVVH in a patient with severe TBI. Application of CVVH may expedite reliable neurologic assessments and facilitate the application of clinical brain death examination following pentobarbital exposure.

A suicide involving intraperitoneal injection of pentobarbital.

We present an unusual case of suicide by intraperitoneal injection of pentobarbital, an overdose of zolpidem and the intake of diazepam, ethanol and other psychoactive substances. The autopsy and specimen collection were conducted in a 10 to 18 h postmortem interval. The toxicological analysis revealed a significantly higher pentobarbital concentration in femoral blood compared to cardiac blood (36 vs. 15 mg/L). On the contrary, zolpidem and diazepam concentrations in cardiac blood (2700 and 590 µg/L) were found to be significantly higher than in femoral blood (1500 and 230 µg/L). These findings point to a postmortem redistribution with a distinct gradient from areas of high drug concentrations in the gastrointestinal tract (zolpidem and diazepam) and the injection site (pentobarbital) to peripheral tissue. Ethanol concentration was 0.95 ‰ which amplified the CNS depression. The choice of this unusual suicide method was associated with the deceased's former job as a veterinarian's assistant. In veterinary medicine, the intraperitoneal injection of a lethal dose of pentobarbital is quite commonly performed to euthanise small animals. Intraperitoneal injection is rare as route of administration in humans.

Enhancement of Pentobarbital-induced Sleep by the Vaporized Essential Oil of Citrus keraji var. kabuchii and its Characteristic Component, y-Terpinene.

Kabuchii (Citrus keraji var. kabuchii hort. ex Tanaka, Rutaceae) is a peculiar Okinawan citrus fruit. Local farmers cultivating various Citrus fruits say that the fragrance of Kabuchii is the most relaxing, but, there are few reports on the biological effects of the essential oil of Kabuchii and its chemical components [1]. In this study, the sedative effects of inhalation of the vaporized Kabuchii essential oil in open field, Rotarod, and pentobarbital sleep tests are compared with diazepam, as a positive control. In the open field test, both Kabuchii essential oil and diazepam decreased the spontaneous motor activity dose-dependently. The reduction in spontaneous motor activity in the 0.3 mg/cage (ca. 0.0278 mg/L) Kabuchii essential oil group was greater than that in the 1 mg/kg diazepam group. In the Rotarod test, Kabuchii did not affect the motor performance, even at the highest dosage tested (3 mg/cage), whereas diazepam decreased it dose- dependently. The effects of the major or characteristic components of Kabuchii, d-limonene, y-terpinene, thymol, and p-cymene, were also evaluated in the- open field and Rotarod tests. y-Terpinene and thymol significantly decreased spontaneous motor activity at a dosage of 0.3 mg/cage, without affecting motor performance. Thus, y-terpinene was estimated to be the main active component. Reduction in spontaneous motor activity by y-terpinene in the open field test was not observed in intranasal zinc sulfate irrigation-induced anosmic mice. In the pentobarbital sleep test, both Kabuchii essential oil and diazepam potentiated pentobarbital-induced loss of the righting reflex (LRR). The LRR duration prolonging effects of both treatments were inhibited by pretreatment with flumazenil, a benzodiazepine receptor antagonist. The LRR latency reducing effect of Kabuchii was not affected by flumazenil, while that of diazepam was suppressed by it. y-Terpinene showed similar potentiating effects on pentobarbital-induced sleep. Thus, vaporized Kabuchii essential oil and its active component, y-terpinene, have sedative effects comparable with diazepam without inducing motor incoordination, which is a well-known side effect of. diazepam.

Therapeutic Drug Monitoring of Pentobarbital: Experience at an Academic Medical Center.

BACKGROUND: Pentobarbital is used for management of intractable seizures and for reducing elevated intracranial pressure. Dosing of pentobarbital can be aided by therapeutic drug monitoring (TDM). There is no commercially available automated assay for measurement of pentobarbital serum/plasma concentrations; consequently, chromatography-based assays are often used. METHODS: Pentobarbital TDM was studied over a 14-year period at an academic medical center. 154 patients (94 adult, 60 pediatric) were identified who had pentobarbital levels ordered at least once during a hospital encounter. Chart review included patient diagnosis, indication for pentobarbital therapy, recent or concomitant medication with other barbiturates, patient disposition, organ donation, pentobarbital dosing changes, and neurosurgical procedures. Pentobarbital serum/plasma concentrations were determined on an automated clinical chemistry platform with a laboratory-developed test adapted from a urine barbiturates immunoassay. RESULTS: Chart review showed therapeutic use of pentobarbital generally consistent with previously published literature. The most common errors observed involved confusion in barbiturate names (eg, mix-up of pentobarbital and phenobarbital in test ordering or in provider notes) that seemed to have minimal impact on TDM effectiveness, with pentobarbital serum/plasma concentrations generally within target ranges. The laboratory-developed pentobarbital immunoassay showed cross-reactivity with phenobarbital and butalbital that was eliminated by alkaline and heat pretreatment. The immunoassay was linear to 20 mcg/mL and correlated closely with gas chromatography-mass spectrometry measurements at a reference laboratory. CONCLUSIONS: Pentobarbital TDM can be performed by immunoassay on an automated clinical chemistry platform, providing an alternative to chromatography-based methods. Confusion in barbiturate names is common, especially pentobarbital and phenobarbital.

Interaction between different extracts of Hypericum perforatum L. from Serbia and pentobarbital, diazepam and paracetamol.

Herb-drug interactions are an important safety concern and this study was conducted regarding the interaction between the natural top-selling antidepressant remedy Hypericum perforatum (Hypericaceae) and conventional drugs. This study examined the influence of acute pretreatment with different extracts of Hypericum perforatum from Serbia on pentobarbital-induced sleeping time, impairment of motor coordination caused by diazepam and paracetamol pharmacokinetics in mice. Ethanolic extract, aqueous extract, infusion, tablet and capsule of Hypericum perforatum were used in this experiment. The profile of Hypericum perforatum extracts as well as paracetamol plasma concentration was determined using RP-HPLC analysis. By quantitative HPLC analysis of active principles, it has been proven that Hypericum perforatum ethanolic extract has the largest content of naphtodianthrones: hypericin (57.77 µg/mL) and pseudohypericin (155.38 µg/mL). Pretreatment with ethanolic extract of Hypericum perforatum potentiated the hypnotic effect of pentobarbital and impairment of motor coordination caused by diazepam to the greatest extent and also increased paracetamol plasma concentration in comparison to the control group. These results were in correlation with naphtodianthrone concentrations. The obtained results have shown a considerable influence of Hypericum perforatum on pentobarbital and diazepam pharmacodynamics and paracetamol pharmacokinetics.

Population pharmacokinetics of pentobarbital in neonates, infants, and children after open heart surgery.

OBJECTIVES: To determine the pharmacokinetics of pentobarbital in neonates, infants, and young children with congenital heart disease after open-heart surgery. STUDY DESIGN: Thirty-five subjects (3.0 days-4.4 years) after open-heart surgery who received pentobarbital as standard of care were enrolled. Serial pharmacokinetic blood samples were obtained. A population-based, nonlinear mixed-effects modeling approach was used to characterize pentobarbital pharmacokinetics. RESULTS: A two-compartment model with weight as a co-variate allometrically expressed on clearance (CL), inter-compartmental clearance, central (V1) and peripheral volume of distributions, bypass grafting time as a co-variate on CL and V1, and age and ventricular physiology as co-variates on CL best described the pharmacokinetics. A typical infant (two-ventricle physiology, 6.9 kg, 5.2 months, and bypass grafting time of 60 minutes) had a CL of 0.12 L/hr/kg, V1 of 0.45 L/kg, and peripheral volume of distributions of 0.98 L/kg. The bypass grafting effect was poorly estimated. For subjects <12 months age, an age effect on CL remained after accounting for weight and was precisely estimated. CONCLUSIONS: Pentobarbital pharmacokinetics is influenced by age and weight. Subjects with single-ventricle physiology demonstrated a 15% decrease in clearance when compared with subjects with two-ventricle physiology.

Identification of the UDP-glucuronosyltransferase responsible for bucolome N-glucuronide formation in rats.

Bucolome N-glucuronide (BCP-NG), a major metabolite of bucolome (BCP), is the first unique N-glucuronide of barbituric acid derivatives to be reported. The purpose of the present study was to identify the UGT isoform(s) responsible for BCP-NG formation in rats. A pharmacokinetic study of BCP and the biliary excretion of BCP-NG was carried out in Wistar rats pretreated with phenobarbital (PB) (PB-pretreated rats), and the results were compared with those of Wistar rats not pretreated with PB (untreated rats). BCP N-glucuronidation activities were studied using hepatic microsomes prepared from Wistar rats pretreated with PB (primarily induces UGT1A1, 1A6 and 2B1) or with clofibric acid (CF, primarily induces UGT1A1 and 1A6), and from Gunn rats (deficiency of UGT1A family), and the results were compared with those of untreated rat microsomes.The plasma elimination clearance value of BCP in PB-pretreated rats was approximately 1.4 times greater than that of untreated rats. The cumulative amount (20.4 +/- 5.9 % of dose) of BCP-NG excreted in PB-pretreated rat bile was approximately 1.5-fold higher than that (13.4 +/- 2.5% of dose) in untreated rat bile, and BCP-NG (5.9 +/- 3.0%) and BCP (3.0 +/- 2.6%) excreted in PB-pretreated rat urine were approximately 3.0- and 1.8-fold higher than those in untreated rat urine (BCP-NG: 2.0 +/- 1.4%; BCP: 1.7 +/- 1.3%), respectively.BCP N-glucuronidation activities in PB- and CF-pretreated microsomes were approximately 1.5- and 1.6-fold higher than in untreated microsomes, respectively. BCP N-glucuronidation activity in the microsomes of Gunn rats was markedly reduced by approximately 8.5% in untreated rat microsomes. The results suggest that UGT 1A1 is primarily responsible for BCP N-glucuronide formation in rats.

Differential neurochemical responses of the canine striatum with pentobarbital or ketamine anesthesia: a 3T proton MRS study.

Although anesthetic agents are known to affect cerebral metabolism, pentobarbital and ketamine have been widely used for animal imaging studies. The purpose of this study is to evaluate alterations in striatum metabolites in dogs between anesthetized with pentobarbital and with ketamine in proton magnetic resonance spectroscopy ((1)H-MRS). (1)H-MRS was performed to ten healthy adult beagle dogs (9-11 kg) at a field strength of 3 T in order to identify metabolic changes after pentobarbital or ketamine administration in the striatum in vivo. Ten dogs were divided into 2 groups as follows: 5 as the pentobarbital-administered group (P group) and 5 as the ketamine-administered group (K group). We found that levels of Glx of the P group was significantly lower than that of the K group (6.90 +/- 0.99 (SD) vs 9.77 +/- 1.14 in 5 dogs, p= 0.003). In addition, the P group also has lower levels of Cr (6.29 +/- 0.44 vs 7.89 +/- 0.91 in 5 dogs, p=0.009) and NAA (5.02 +/- 0.65 vs 6.45 +/- 1.13 in 5 dogs, p=0.041) compared to the K group. However, there were no significant difference between the P group and the K group in striatal levels of Cho and Ins (p>0.1). We demonstrated that MRS-measured metabolites in the specific regions of the brain can be influenced by anesthetic agents.

Relative distribution of drugs in decomposed skeletal tissue.

Skeletal tissues from a domestic pig exposed to amitriptyline, diazepam, and pentobarbital were analyzed to determine the relative distribution of these drugs in bone. Following drug exposure and euthanasia, remains were allowed to decompose outdoors to complete skeletonization between summer 2007 and fall 2009. Remains were recovered and separated according to bone type. Twelve different bone types were pulverized and sampled in triplicate. Each bone sample underwent methanolic extraction (96 h, 50 °C), followed by solid-phase extraction and gas chromatography-mass spectrometry in the selected ion monitoring mode. Mass-normalized assay responses underwent ANOVA with post-hoc testing, revealing bone type as a main effect for all three drugs, but not for the diazepam metabolite (nordiazepam). The assay response varied with respect to bone type by factors of 27, 39, and 20 for pentobarbital, diazepam, and amitriptyline, respectively. The relative distribution between bone type was qualitatively similar for the three administered drugs analyzed for, with the largest response obtained from rib for all three drugs. This is the first study, to the authors' knowledge, of the distribution of different drugs in various decomposed skeletal tissues in a controlled experiment using an animal model of comparable physiology to humans. These data have implications for the interpretive value of forensic drug measurements in skeletal tissues.

Epidural pentobarbital delivery can prevent locally induced neocortical seizures in rats: the prospect of transmeningeal pharmacotherapy for intractable focal epilepsy.

PURPOSE: To determine whether epidural pentobarbital (PB) delivery can prevent and/or terminate neocortical seizures induced by locally administered acetylcholine (Ach) in freely moving rats. METHODS: Rats were implanted permanently with an epidural cup placed over the right parietal cortex with intact dura mater. Epidural screw-electrodes, secured to the cup, recorded local neocortical EEG activity. In the seizure-termination study, Ach was delivered into the epidural cup, and after the development of electrographic and behavioral seizures, the Ach solution was replaced with either PB or artificial cerebrospinal fluid (aCSF; control solution). In the seizure-prevention study, the epidural Ach delivery was preceded by a 10-min exposure of the delivery site to PB or aCSF. Raw EEG recordings, EEG power spectra, and behavioral events were analyzed. RESULTS: Ach-induced EEG seizures associated with convulsions, which were unaffected by epidural aCSF applications, were terminated by epidurally delivered PB within 2-2.5 min. Epidural deliveries of PB before Ach applications completely prevented the development of electrographic and behavioral seizures, whereas similar deliveries of aCSF exerted no influence on the seizure-generating potential of Ach. CONCLUSIONS: This study showed for the first time that epidural AED delivery can prevent, as well as terminate, locally induced neocortical seizures. The findings support the viability of transmeningeal pharmacotherapy for the treatment of intractable neocortical epilepsy.

Circadian regulation of arousal: role of the noradrenergic locus coeruleus system and light exposure.

STUDY OBJECTIVES: Noradrenergic locus coeruleus (LC) neurons regulate arousal. Previous studies have shown that noradrenergic LC neurons exhibit a circadian rhythm in impulse activity, which peaks during the active period. This is mediated by an indirect circuit projection from the suprachiasmatic nucleus (SCN) to the LC. Here we sought to evaluate the hypothesis that the LC regulates the circadian properties of the sleep-wake cycle. DESIGN: Sprague-Dawley rats maintained on a light-dark (LD) schedule or in constant darkness (DD) for 3 to 4 weeks were treated with DSP-4, a neurotoxic agent specific for noradrenergic-LC projections. Vigilance states were analyzed before and 3 weeks after LC lesion. The DSP-4 lesion was verified by immunohistochemistry of noradrenergic fibers in the frontal cortex. SETTING: University of Pennsylvania. PATIENTS OR PARTICIPANTS: N/A. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: DSP-4 decreased the amplitude of the sleep-wake rhythm in LD animals by significantly decreasing wakefulness and increasing sleep during the active period. However, DSP-4 had no effect on the sleep-wake cycle of DD animals. Moreover, DD itself decreased the amplitude of the sleep-wake cycle similar to that of the neurotoxic lesion of the noradrenergic system in LD animals. Analysis of noradrenergic fiber staining in the frontal cortex revealed that this effect was associated with fewer fibers or boutons in nonlesioned DD rats than in nonlesioned LD animals. CONCLUSIONS: Noradrenergic LC neurons provide a circadian regulation of the sleep-wake cycle, and the maintenance of LC function depends on light exposure. Light deprivation induces a loss of noradrenergic fibers, which in turn decreases the amplitude of the sleep-wake rhythm.

Análisis de los efectos de plantas medicinales de Bangladesh en la duración del sueño inducido por pentobarbital en ratones / Screening of Bangladeshi medicinal plants for their effects on pentobarbital-induced sleeping time in mice

Se analizó la actividad en el sistema nervioso central de los extractos acuosos de cuarenta plantas medicinales de Bangladesh mediante el estudio de la duración del sueño inducido por pentobarbital. Doce de las plantas mostraron un aumento significativo de la duración del sueño, mientras que seis mostraron una disminución significativa. Woodfordia fruticosa y Uraria lagopodioides presentaron un mayor efecto depresor que el diazepam

Aqueous extracts of forty medicinal plants of Bangladesh have been screened for central nervous system activity by pentobarbital-induced sleeping time test. While twelve plants showed signifi cant increase in sleeping time, six plants showed significant decrease. Woodfordia fruticosa and Uraria lagopodioides exhibited a better depressant effect than diazepam

A study of the in vitro interaction between lidocaine and premedications using human liver microsomes.

OBJECTIVE: To investigate potential interactions between lidocaine (lignocaine) metabolism and premedication drugs, i.e. psychotropic and antianxiety agents (diazepam, midazolam), hypnotics (pentobarbital, thiamylal), depolarizing neuromuscular blocking agents (vecuronium, pancuronium and suxamethonium), an antihypertensive agent (clonidine) and an H2-receptor blocking agent (cimetidine) using human liver microsomes in vitro. METHODS: The interaction effects between lidocaine and premedication were examined using human liver microsomal preparations and monitored for enzyme activity. The lidocaine and its main metabolite (monoethylglycinexylide) were measured by HPLC/UV. RESULTS: Lidocaine metabolism was non-competitively inhibited by midazolam (Ki = 77.6 microM). Thiamylal was a competitive inhibitor of lidocaine metabolism (Ki = 885 microM). Cimethidine, pancuronium and vecuronium weakly inhibited lidocaine metabolism in a concentration-depend manner over the therapeutic range in human liver microsomes. On the contrary, suxamethonium, pentobarbital and clonidine did not inhibit lidocaine metabolism over the therapeutic range in human liver microsomes. CONCLUSION: These results show that the interactions between lidocaine and midazolam and thiamylal are of potential toxicological and clinical significance.

Transgenic mice with a hypomorphic NADPH-cytochrome P450 reductase gene: effects on development, reproduction, and microsomal cytochrome P450.

A mouse model with a hypomorphic NADPH-cytochrome P450 reductase (Cpr) gene (designated Cpr(low) allele) was generated and characterized in this study. The Cpr gene in these mice was disrupted by the insertion of a neo gene in intron 15, which led to 74 to 95% decreases in CPR expression in all tissues examined, including olfactory mucosa, adrenal gland, brain, testis, ovary, lung, kidney, liver, and heart. In the liver, a pattern of pericentral distribution of CPR protein was preserved in the Cpr(low/low) mice, despite an overall reduction in CPR expression. Genotype distribution in F2 pups indicated limited embryonic lethality associated with the Cpr(low) allele, a finding that confirms the role of CPR-dependent enzymes in development. Adult male homozygotes had decreased body weight and decreased heart, lung, and kidney weights, whereas homozygous Cpr(low) females, which had increased serum testosterone and progesterone and decreased copulatory activities, were infertile. Furthermore, adult Cpr(low/low) mice had decreased plasma cholesterol, and some mice developed mild centrilobular hepatic lipidosis. In addition, despite apparently compensatory increases in total microsomal cytochrome P450 content in the liver and kidney, the decreases in CPR expression were accompanied by reductions in systemic clearance of pentobarbital, as well as in hepatic microsomal metabolism of acetaminophen and testosterone. These phenotypes illustrate the potential impact of a globally decreased CPR activity in human adults, and this novel knock-in mouse model provides a unique opportunity for further explorations of the in vivo roles of CPR and CPR-dependent enzymes.

Comparison of the effects of propofol and pentobarbital on left ventricular adaptation to an increased afterload.

The purpose of this study was to compare the hemodynamic effects of pentobarbital and propofol and their effects on cardiovascular adaptation to an abrupt increase in left ventricular afterload. Experiments were performed in 12 open-chest pigs instrumented for measurement of aortic pressure and flow, and left ventricular pressure and volume. In one group (n = 6), anesthesia was obtained with sodium pentobarbital (3 mg x kg(-1) x h(-1)), and, in the second group B (n = 6), with propofol (10 mg x kg(-1) x h(-1)). Both groups received sufentanil (0.5 microg x kg(-1) x h(-1)) and pancuronium bromide (0.1 mg x kg(-1)). Left ventricular function was assessed by the slope of end-systolic pressure-volume relationship and stroke work. After baseline recordings, left ventricular afterload was increased by aortic banding. The cardiovascular adaptations triggered by the aortic banding, such as tachycardia, vasoconstriction, and augmentation of myocardial contractility were prevented with propofol, suggesting interference with the baroreflex. Increase in left ventricular afterload decreased mechanical efficiency, regardless of anesthetic agent. These results showed that pentobarbital at 3 mg x kg(-1) x h(-1) has less deleterious hemodynamic effects than propofol at 10 mg x kg(-1) x h(-1).

Reduced sensitivity to ketamine and pentobarbital in mice lacking the N-methyl-D-aspartate receptor GluRepsilon1 subunit.

Ketamine is an IV anesthetic with N-methyl-d-aspartate receptor (NMDAR)-blocking properties. However, it is still unclear whether ketamine's general anesthetic actions are mediated primarily via blockade of NMDAR. Functional NMDARs are composed by the assembly of a GluRzeta1 (NR1) subunit with GluRepsilon (GluRepsilon1-4; NR2A-D) subunits, which confer unique properties on native NMDARs. We hypothesized that animals deficient in GluRepsilon1, an abundant and ubiquitously postnatally expressed NMDAR subunit, might be resistant to the effects of ketamine. Here, we evaluated a righting reflex to determine the general anesthetic/hypnotic potency of ketamine administered intraperitoneally to GluRepsilon1 knockout mice and compared these results with those for wild-type mice. Mutant mice were more resistant to ketamine than control mice. Unexpectedly, mutant mice were also more resistant to pentobarbital, which is thought not to interact with NMDAR at clinically relevant concentrations. Although these data in no way eliminate the possibility of the involvement of the NMDAR GluRepsilon1 subunit in mediation of ketamine anesthesia/hypnosis, they suggest the difficulties with interpretation of altered anesthetic sensitivity in knockout animal models.