Preoperative vitamin-rich carbohydrate loading alleviates postoperative cognitive dysfunction in aged rats.

With the acceleration of an aging population, postoperative cognitive dysfunction (POCD) has become a large problem. Preoperative carbohydrate (CHO) loading has been reported to attenuate surgery stress response and insulin resistance. The present study aimed to investigate whether preoperative vitamin-rich CHO loading has an effect on POCD, endoplasmic reticulum (ER) stress, and apoptosis. Eighty male Sprague-Dawley rats (20-month old) were randomly assigned to four groups (20 per group): control group (no anesthesia and surgery), fasting group (fasting 14 h before surgery), water group (oral water 3 h before surgery), and CHO group (oral vitamin-rich CHO 3 h before surgery). The POCD rat model was established by splenectomy under intraperitoneal injection of pentobarbital sodium. Cognitive function was assessed using the Morris water maze (MWM) after surgery. The levels of endoplasmic reticulum (ER) stress markers and apoptosis related proteins in the hippocampus were examined by western blot analysis. The vitamin-rich CHO treated animals performed better in the MWM tests than the animals in the fasting and water groups. Furthermore, preoperative CHO loading reduced ER stress and neuronal apoptosis in the hippocampus of aged rats, as indicated by the protein biomarkers of GRP78, eIF2a, Beclin1, Bax, and Bcl-2. In conclusion, preoperative vitamin-rich CHO loading could improve POCD by attenuating ER stress and neural apoptosis, providing a basis as a potential treatment against POCD.

The effects of vitamin-rich carbohydrate pretreatment on the surgical stress response and S-100ß after splenectomy in elderly rats.

BACKGROUND: Preoperative oral carbohydrates has been suggested to attenuate insulin resistance and decrease postoperative complications. In this study, a vitamin-rich carbohydrate beverage was administered before surgery in an animal model to investigate its effects on the surgical stress response and S-100ß levels. METHODS: Thirty aged male Sprague-Dawley rats were randomly assigned to three groups: control group (n = 6), fasting group (n = 12), and carbohydrate-treated group (CHO group, n = 12). Rats in the control group were not given any treatment. Rats in the fasting group received splenectomy after 12 h of fasting. In the CHO group, rats were given 5 ml of vitamin-rich carbohydrate by gavage 2 h before surgery. Fasting plasma glucose, insulin, insulin resistance (HOMA-IR index, IRI), the S-100ß protein level, and the inflammatory mediators IL-1ß, IL-6 and TNF-α were assessed after surgery (postoperative day (POD) 1 and 3). RESULTS: Postoperative insulin resistance was significantly greater in the fasting group than in the control and CHO group. The median plasma S-100ß level was significantly higher in the fasting group than in the control and CHO groups on POD 1. The median plasma IL-1ß level was significantly lower in the CHO group than in the fasting group on POD 1; however, no other differences in the concentrations of immunological biomarkers of stress were found between the fasting group and the CHO group. CONCLUSIONS: Vitamin-rich carbohydrate pretreatment attenuated the metabolic aspect of the surgical stress response and decreased the level of plasma S-100ß, which may decrease the risk of postoperative complications in elderly rats.

Neonatal exposure to propofol affects interneuron development in the piriform cortex and causes neurobehavioral deficits in adult mice.

RATIONALE: Animal studies have shown that early postnatal propofol administration is involved in neurobehavioral alterations in adults. However, the underlying mechanism is not clear. METHODS: We used c-Fos immunohistochemistry to identify activated neurons in brain regions of neonatal mice under propofol exposure and performed behavioral tests to observe the long-term consequences. RESULTS: Exposure to propofol (30g or 60 mg/kg) on P7 produced significant c-Fos expression in the deep layers of the piriform cortex on P8. Double immunofluorescence of c-Fos with interneuron markers in the piriform cortex revealed that c-Fos was specifically induced in calbindin (CB)-positive interneurons. Repeated propofol exposure from P7 to P9 induced behavioral deficits in adult mice, such as olfactory function deficit in a buried food test, decreased sociability in a three-chambered choice task, and impaired recognitive ability of learning and memory in novel object recognition tests. However, locomotor activity in the open-field test was not generally affected. Propofol treatment also significantly decreased the number of CB-positive interneurons in the piriform cortex of mice on P21 and adulthood. CONCLUSIONS: These results suggest that CB-positive interneurons in the piriform cortex are vulnerable to propofol exposure during the neonatal period, and these neurons are involved in the damage effects of propofol on behavior changes. These data provide a new target of propofol neurotoxicity and may elucidate the mechanism of neurobehavioral deficits in adulthood.

Propofol Exposure in Early Life Induced Developmental Impairments in the Mouse Cerebellum.

Propofol is a widely used anesthetic in the clinic while several studies have demonstrated that propofol exposure may cause neurotoxicity in the developing brain. However, the effects of early propofol exposure on cerebellar development are not well understood. Propofol (30 or 60 mg/kg) was administered to mice on postnatal day (P)7; Purkinje cell dendritogenesis and Bergmann glial cell development were evaluated on P8, and granule neuron migration was analyzed on P10. The results indicated that exposure to propofol on P7 resulted in a significant reduction in calbindin-labeled Purkinje cells and their dendrite length. Furthermore, propofol induced impairments in Bergmann glia development, which might be involved in the delay of granule neuron migration from the external granular layer (EGL) to the internal granular layer (IGL) during P8 to P10 at the 60 mg/kg dosage, but not at the 30 mg/kg dosage. Several reports have suggested that the Notch signaling pathway plays instructive roles in the morphogenesis of Bergmann glia. Here, it was revealed that propofol treatment decreased Jagged1 and Notch1 protein levels in the cerebellum on P8. Taken together, exposure to propofol during the neonatal period impairs Bergmann glia development and may therefore lead to cerebellum development defects. Our results may aid in the understanding of the neurotoxic effects of propofol when administrated to infants.

Role of dorsal root ganglion K2p1.1 in peripheral nerve injury-induced neuropathic pain.

Abstract: Peripheral nerve injury-caused hyperexcitability and abnormal ectopic discharges in the primary sensory neurons of dorsal root ganglion (DRG) play a key role in neuropathic pain development and maintenance. The two-pore domain background potassium (K2P) channels have been identified as key determinants of the resting membrane potential and neuronal excitability. However, whether K2P channels contribute to neuropathic pain is still elusive. We reported here that K2P1.1, the first identified mammalian K2P channel, was highly expressed in mouse DRG and distributed in small-, medium-, and large-sized DRG neurons. Unilateral lumbar (L) 4 spinal nerve ligation led to a significant and time-dependent reduction of K2P1.1 mRNA and protein in the ipsilateral L4 DRG, but not in the contralateral L4 or ipsilateral L3 DRG. Rescuing this reduction through microinjection of adeno-associated virus-DJ expressing full-length K2P1.1 mRNA into the ipsilateral L4 DRG blocked spinal nerve ligation-induced mechanical, thermal, and cold pain hypersensitivities during the development and maintenance periods. This DRG viral microinjection did not affect acute pain and locomotor function. Our findings suggest that K2P1.1 participates in neuropathic pain development and maintenance and may be a potential target in the management of this disorder.

Liver X Receptor ß Is Involved in Formalin-Induced Spontaneous Pain.

Increasing evidence indicates that the liver X receptor(LXR) ß modulates inflammatory pain. However, the molecular mechanisms through which LXRß modulates pain are unclear. Here, we found that LXRß-null mice responded more strongly to acute noxious stimuli than wild-type (WT) littermates (in the hot plate and Hargreaves tests) and had augmented tonic inflammatory pain (in the formalin test). This increased reactivity to inflammatory pain was accompanied by enhanced formalin-evoked Fos and pERK staining of second-order nociceptive neurons. Immunohistochemistry showed that the expression of CGRP, SP, and IB4 was increased in the lamina I-II of the lumbar dorsal horns in formalin-injected LXRß knockout (KO) mice compared with the WT controls. In addition, LXRß deletion in the mice enhanced the formalin-induced inflammation with more activated microglia and astrocytes in the spinal cord. Furthermore, the levels of pro-inflammatory cytokines (IL-1ß ,TNF-α) as well as NFκB in the formalin-injected paw were elevated by the loss of LXRß. Taken together, these data indicate that LXRß is involved in acute as well as inflammatory pain, and thus, it may be considered as a new target for the development of analgesics.

Propofol Administration During Early Postnatal Life Suppresses Hippocampal Neurogenesis.

Propofol is currently one of the most widely used intravenous anesthetics and has been indicated to induce cognitive dysfunction in adults. Here, we investigated the effects of propofol exposure during early postnatal life on hippocampal neurogenesis. Propofol (30 or 60 mg/kg) was administered to mice on either postnatal day (P) 7 or P7-P9; cell proliferation and neurogenesis in the dentate gyrus (DG) were evaluated on P8 or P17. It showed that exposure to propofol on P7 decreased hippocampal cell proliferation as indicated by BrdU and Sox2 immunostaining at P8 in propofol treatment at the dosage of 60 mg/kg but not at the dosage of 30 mg/kg. Western blots revealed propofol treatment decreased Akt or extracellular signal-related kinase (ERK) 1/2 phosphorylation in the hippocampus at P8. Propofol treatment on P7 to P9 reduced the numbers of newly formed neurons in the DG at P17, which was accompanied by delay of granule neuron maturation and decreased the density of dendritic spines, particularly the mushroom-shaped mature spines. Furthermore, the in vitro findings indicated propofol suppressed cell proliferation and cell mitosis and activated apoptosis of C17.2 neural stem cell line in a dose-dependent manner. These findings suggest that propofol impairs cell proliferation and inhibits neurogenesis in the immature mouse brain and thus is possibly involved in the cognitive dysfunction induced by propofol anesthesia.

Landiolol in the treatment of the intraoperative supraventricular tachycardia: a multicenter, randomized, double-blind, placebo-controlled study.

BACKGROUND: Supraventricular tachycardia during the induction of anesthesia may carry a higher risk. STUDY OBJECTIVE: The aim of this study was to evaluate efficacy and safety of intravenous landiolol in Chinese patients with intraoperative supraventricular tachycardia during anesthesia. DESIGN: A randomized, double-blind, placebo-controlled, parallel-group, multicenter, phase 2 study. SETTING: Eight sites of Chinese hospitals. PATIENTS: Men and women aged 18 to 70 years with the intraoperative supraventricular tachycardia (heart rate [HR], ≥100 beats/min) or the supraventricular tachycardia outside of the sinus tachycardia lasting more than 1 minute. INTERVENTIONS: Patients received landiolol or placebo-0.125 mg kg(-1) min(-1) (1 minute) loading→0.04 mg kg(-1) min(-1) (10 minutes) continuous. MEASUREMENTS: The proportion of patients receiving rescue medication (esmolol) when the reduction of HR did not exceed 10% after intravenous landiolol for 5 minutes. Other secondary efficacy end points include HR, blood pressure, rate pressure product, and electrocardiogram; the improvement of supraventricular tachycardia; the time it takes for the decrease of the HR to reach more than 10%; and the time it takes for the HR to reach <100 beats/min. MAIN RESULTS: Efficacy and safety were evaluated for 240 patients who received study drug. Lower proportions of patients received rescue medication in the landiolol group (7.63%) compared with that in the placebo group (80.33%) (P < .0001). Suppression of HR and rate pressure product was generally more potent(P < .0001), and higher proportions of patients improved supraventricular tachycardia (P < .0001) in the landiolol group. The most frequent adverse event was hypotension. CONCLUSION: Intravenous landiolol (loading dose of 0.125 mg/kg) may effectively control intraoperative supraventricular tachycardia during anesthesia. It inhibited the increases in HR during the induction of anesthesia. The effect of landiolol on blood pressure was minimal without decreasing diastolic blood pressure and with the minor reduction of systolic blood pressure (ClinicalTrials.gov number, ChiCTR-TRC-12003021).

Age and sex differences in vascular responsiveness in healthy and trauma patients: contribution of estrogen receptor-mediated Rho kinase and PKC pathways.

Several medical conditions exhibit age- and sex-based differences. Whether or not traumatic shock exhibits such differences with regard to vascular responsiveness is not clear. In a cohort of 177 healthy subjects and 842 trauma patients (21-82 years) as well as different ages (4, 8, 10, 14, 18, and 24 wk; 1 and 1.5 years) and sexes of Sprague-Dawley normal and traumatic shock rats, the age- and sex-based differences of vascular responsiveness and the underlying mechanisms were investigated. Middle-aged and young women as well as female rats of reproductive age had higher vascular responsiveness in the normal condition and a lower decrease in vascular responsiveness after traumatic shock than older men and male rats of identical age. Exogenous supplementation of 17ß-estrdiol increased vascular reactivity in both male and femal rats of 8-24 wk and preserved vascular responsiveness in rats following traumatic shock. No effect was observed in rats 1 to 1.5 years. These protective effects of estrogen were closely related to G protein-coupled receptor (GPR)30, estrogen receptor-mediated Rho kinase, and PKC pathway activation. Vascular responsiveness exhibits age- and sex-based differences in healthy subjects and trauma patients. Estrogen and its receptor (GPR30) mediated activation of Rho kinase and PKC using genomic and nongenomic mechanisms to elicit protective effects in vascular responsiveness. This finding is important for the personalized treatment for several age- and sex-related diseases involving estrogen.

Anesthetic management of conjoined twins undergoing one-stage surgical separation: A single center experience.

OBJECTIVE: To summarize our experience in the anesthetic management of conjoined twins undergoing one-stage surgical separation. METHODOLOGY: Medical records of conjoined twins admitted to our hospital for treatment and considered for surgical separation from 1996 to present were retrospectively reviewed. Four cases of conjoined twins underwent one-stage surgical separation under general anesthesia. Preoperative evaluation was performed to determine the extent of anatomical conjunction and associated anomalies. Anesthesia was simultaneously induced in all conjoined twins. The intubation procedure was successfully performed with the head slightly rotated to each baby's side, followed by the administration of vecuronium. Anesthetic agents were administered according to the estimated weight of each baby. One case of conjoined twins underwent surgical separation with cardiopulmonary bypass due to shared hearts. Results : All conjoined twins were successfully separated. No significant respiratory or cardiac events occurred during surgery except for one twin, which died after separation because of complicated congenital heart disease. Conclusions : Accurate preoperative evaluation, respiratory and circulatory management, and close cooperation of the multidisciplinary team are important aspects of anesthetic management of conjoined twins surgery.

Proteomic analysis of effluents from perfused human heart for transplantation: identification of potential biomarkers for ischemic heart damage.

BACKGROUND: Biomarkers released from the heart at early stage of ischemia are very important to diagnosis of ischemic heart disease and salvage myocytes from death. Known specific markers for blood tests including CK-MB, cardiac troponin T (cTnT) and cardiac troponin I (cTnI) are released after the onset of significant necrosis instead of early ischemia. Thus, they are not good biomarkers to diagnose myocardial injury before necrosis happens. Therefore, in this study, we performed proteomic analysis on effluents from perfused human hearts of donors at different ischemic time. RESULTS: After global ischemia for 0 min, 30 min and 60 min at 4°C, effluents from five perfused hearts were analyzed respectively, by High performance liquid chromatography-Chip-Mass spectrometry (HPLC-Chip-MS) system. Total 196 highly reliable proteins were identified. 107 proteins were identified at the beginning of ischemia, 174 and 175 proteins at ischemic 30 min and ischemic 60 min, respectively. With the exception of cardiac troponin I and T, all known biomarkers for myocardial ischemia were detected in our study. However, there were four glycolytic enzymes and two targets of matrix metalloproteinase released significantly from the heart when ischemic time was increasing. These proteins were L-lactate dehydrogenase B(LDHB), glyceraldehyde-3-phosphate dehydrogenase, glucose-6-phosphate isomerase (GPI), phosphoglycerate mutase 2 (PGAM2), gelsolin and isoform 8 of titin. PGAM2, LDHB and titin were measured with enzyme-linked immunosorbent assays kits. The mean concentrations of LDHB and PGAM2 in samples showed an increasing trend when ischemic time was extending. In addition, 33% identified proteins are involved in metabolism. Protein to protein interaction network analysis showed glycolytic enzymes, such as isoform alpha-enolase of alpha-enolase, isoform 1 of triosephosphate isomerase and glyceraldehyde-3-phosphate dehydrogenase, had more connections than other proteins in myocardial metabolism during ischemia. CONCLUSION: It is the first time to use effluents of human perfused heart to study the proteins released during myocardial ischemia by HPLC-Chip-MS system. There might be many potential biomarkers for mild ischemic injury in myocardium, especially isoform 8 of titin and M-type of PGAM2 that are more specific in the cardiac tissue than in the others. Furthermore, glycolysis is one of the important conversions during early ischemia in myocardium. This finding may provide new insight into pathology and biology of myocardial ischemia, and potential diagnostic and therapeutic biomarkers.

Amitriptyline upregulates EAAT1 and EAAT2 in neuropathic pain rats.

Excitatory amino acid transporters (EAATs) appear to participate in the pathogenesis of neuropathic pain. The present study was performed to evaluate the effects of the tricyclic antidepressant amitriptyline on the expressions of EAATs in neuropathic pain rats. Using spared nerve injured (SNI) male Sprague Dawley rats, we found that SNI induced an initial EAATs upregulation on postoperative day 1 within the ipsilateral spinal cord dorsal horn, followed by a downregulation on postoperative days 3 and 5. Intraperitoneal administration of amitriptyline reversed the downregulation of EAATs in SNI rats on postoperative days 3-5 and attenuated the mechanical allodynia. We further demonstrated that administration of amitriptyline alone induced an upregulation of EAATs in sham-operated rat but do not produce an antinociceptive effect. These results indicate that amitriptyline could increase the expression of EAATs which may be one of its mechanisms in the treatment of neuropathic pain.

Vagus nerve stimulation may be used in the therapy of myocarditis.

Although a large number of different causes have been identified as leading to myocarditis, inflammation plays a pivotal role in its pathological process. No specific methods are available in the therapy of myocarditis except symptomatic treatment. Vagus nerve stimulation has been found to lower the heart rate and recover the normal heart rhythm which may relieve the cardiac symptoms in myocarditis. Furthermore, the acetylcholine that secreted by vagus nerve stimulation was found to inhibit the production of such inflammatory cytokines as tumor necrosis factor-alpha (TNF-alpha), interleukin 1beta (IL-1beta). Based on the above, we hypothesized that vagus nerve stimulation can be used in the therapy of myocarditis and lead to relief of symptoms and inhibition of inflammatory process which may kill two birds with one stone.

[Effect of orexin-A on recovery from ketamine anesthesia in aged rats].

OBJECTIVE: To observe the effect of orexin-A on the recovery and cognitive function of aged rats after ketamine anesthesia. METHODS: Fifty-five aged rats were divided randomly into control group, model control group, 1 nmol/L Orexin-A group, and 4 nmol/L Orexin-A group. In the latter 3 groups, the rats received an intraperitoneal injection of ketamine at 100 mg/kg, and normal saline was injected in the control group. Ten minutes after the injections, the rats received intraventricular injections of artificial cerebrospinal fluid (control and model control group) or of 10 microl 1 or 4 nmol/L Orexin-A as indicated. The behavioral changes of the rats were assessed by the duration of loss of righting reflex (LORR). Electroencephalogram (EEG) recordings were used to evaluate the changes in rat brain activity by comparison of the percent of sigma wave in EEG before and after the intraventricular injections. Morris water maze was used to test the learning and spatial localization abilities of the rats. RESULTS: Ketamine resulted in obvious impairment of learning and memory abilities of the aged rats. Orexin-A at 4 nmol/L induced significant decrease in the duration of LORR and marked reduction of sigma activities in anesthetic rats (P<0.05), and obviously improved the learning and spatial localization abilities of the rats after anesthesia (P<0.05). CONCLUSION: Orexin-A can promote the recovery and improve the cognitive function of aged rats after ketamine anesthesia.

Isoflurane reduces the synthesis of surfactant-related protein a of alveolar type II cells injured by H2O2.

The influence of isoflurane (Iso) on the synthesis of surfactant-related protein A (SP-A) of alveolar type II (AT II) cells in primary culture and after injury by H2O2 was investigated. AT II cells were isolated and purified from adult Sprague-Dawley rats and used for experiments after 32 h in primary culture. The cell cultures were randomized to six groups (n = 8 in each group): control group (no treatment), 0.28 mM Iso group, 2.8 mM Iso group, 75 microM H2O2 group, 75 microM H2O2 + 0.28 mM Iso group, and 75 microM H2O2 + 2.8 mM Iso group. Each group was continuously incubated for 3 h after administration of Iso and/or H2O2. The intracellular SP-A and the SP-A of the culture medium were measured with an enzyme-linked immunosorbent assay (ELISA). Iso significantly decreased the intracellular SP-A content and that of the culture medium, and aggravated the decrease of SP-A content induced by H2O2. These findings suggest that Iso itself may decrease SP-A synthesis of AT II cells in vitro, and aggravate the damage to AT II cells under peroxidation conditions.

Effect of terbutaline on alveolar liquid clearance after oleic acid-induced lung injury in rats.

OBJECTIVE: To investigate whether terbutaline affects alveolar liquid clearance after oleic acid-induced lung injury in rats. METHODS: Forty healthy Wistar rats (weighing 250-280 g) were randomly divided into five groups (n=8 in each group): the normal control group (control group), oleic acid injury group (injury group), terbutaline-treated group (terbutaline group), terbutaline plus amiloride-treated group (terbutaline+amiloride group) and terbutaline plus ouabain-treated group (terbutaline+ouabain group). Acute lung injury model was induced by intravenous oleic acid (0.25 ml/kg body weight). 24 hours later, 1.5 microCi (125) I-labeled 5% albumin solution (5 ml/kg body weight) was dripped into the lungs through trachea. The alveolar liquid clearance rate, extravascular lung water content, and arterial blood gas were measured 1 hour thereafter. RESULTS: At 24 hours after infusion of oleic acid, the rats developed pulmonary edema and severe hypoxemia, with the alveolar liquid clearance rate decreased by 49.2% and the extravascular lung water content elevated by 47.9%. Compared with the rats in the injury group, terbutaline (10(-4) mol/L) significantly increased the alveolar liquid clearance rate, decreased the extravascular lung water content and improved hypoxemia. The effect of terbutaline was partly blocked by amiloride and ouabain, which were inhibitors of sodium transport. Terbutaline increased the alveolar liquid clearance rate by 63.7%, and amiloride and ouabain reduced the alveolar liquid clearance rate by 54.7% and 56.8%, respectively. CONCLUSIONS: Terbutaline can accelerate alveolar liquid clearance through increasing sodium transport to attenuate pulmonary edema, thus improving gas exchange, which may have therapeutical effect on pulmonary edema after acute lung injury.

Comparative proteomics analysis of differentially expressed phosphoproteins in adult rat ventricular myocytes subjected to diazoxide preconditioning.

Mitochondrial ATP sensitive potassium channels (mitoK(ATP) channels) are involved in the cardioprotection afforded by ischemic preconditioning (IPC) and diazoxide, a selective mitoK(ATP) channel opener. The activation of some kinases, including phoshoprotein kinase (PKC)-epsilon and mitogen-activating protein kinases (MAPK), is involved in signal conduction of preconditioning downstream from mitoK(ATP) channel opening. Diazoxide can open mitoK(ATP) channels and activate PKC-epsilon, which will phosphorylate some substrate proteins. These proteins that exhibit altered post-translational modification via phosphorylation due to diazoxide pretreatment may be the target molecules and play an important role in cellular protection after mitoK(ATP) channel opening. To analyze and identify the phosphoproteins associated with diazoxide preconditioning, phosphoprotein enrichment and comparative two-dimensional gel electrophoresis (2D-GE) were used. Cultured adult rat ventricular myocytes were pretreated in the presence and absence of 100 micronol/1l diazoxide for 10 min and enriched phosphoproteins from control myocytes and those pretreated with 100 micromol/l diazoxide were separated by 2D-GE and stained with a silver staining kit. Phosphoproteins of interest were further identified by matrix-assisted laser desorption ionization tandem mass spectrometry (MALDI-TOF MS). Eight protein spots with different abundance were found, of which six differentially expressed proteins were identified by MALDI-TOF MS. They included 94 kDa glucose-regulated protein, calpactin I heavy chain, chaperonin containing TCP-1 zeta subunit, hypothetical protein XP_346548, ferritin light chain and ferritin light chain 2. These findings provide new clues to understanding the mechanism of ischemic preconditioning in cardiomyocytes downstream from mitoK(ATP) channel opening.

Effect of isoflurane on proliferation and Na+,K+-ATPase activity of alveolar type II cells injured by hydrogen peroxide.

The influence of isoflurane (Iso) on proliferation and Na+,K+-ATPase activity of alveolar type II cells (ATII cells) injured by hydrogen peroxide (H2O2) was investigated. ATII cells isolated and purified from adult Sprague-Dawley rats were randomly divided into six groups: control group, 0.28 mM Iso group, 2.8 mM Iso group, 75 microM H2O2 group, 75 microM H2O2 + 0.28 mM Iso group, and 75 microM H2O2 + 2.8 mM Iso group. After primary culture for 32 hours, the proliferation of ATII cells was detected by MTT assay, and after culture for 24 hours the activity of Na+,K+-ATPase and lactate dehydrogenase (LDH) in the cells, and malonaldehyde (MDA) content of the culture medium, were measured by colorimetry. It was found that 0.28 mM and 2.8 mM Iso had no effect on the proliferation of ATII cells (p > 0.05), but 75 microM H2O2 inhibited their proliferation (p < 0.05) compared with untreated controls; 0.28 mM and 2.8 mM Iso significantly decreased Na+,K+-ATPase activity of ATII cells compared with untreated control cells (p < 0.05), and 75 microM H2O2 markedly decreased Na+,K+-ATPase activity of ATII cells (p < 0.01) with untreated control cells. 0.28 mM and 2.8 mM Iso aggravated the decrease of Na+,K+-ATPase activity induced by H2O2. Iso had no effect on LDH activity and MDA content of the culture medium of normal ATII cells, but significantly increased LDH activity and MDA content of the culture medium of ATII cells injured by H2O2. These findings suggest that Iso itself may decrease the activity of Na+,K+-ATPase of ATII cells in vitro and further damage the cells' function under peroxidation conditions, but has no effect on the proliferation of ATII cells.

Changes in liquid clearance of alveolar epithelium after oleic acid-induced acute lung injury in rats.

OBJECTIVE: Impaired active fluid transport of alveolar epithelium may involve in the pathogenesis and resolution of alveolar edema. The objective of this study was to explore the changes in alveolar epithelial liquid clearance during lung edema following acute lung injury induced by oleic acid. METHODS: Forty-eight Wistar rats were randomly divided into six groups, i.e., injured, amiloride, ouabain, amiloride plus ouabain and terbutaline groups. Twenty-four hours after the induction of acute lung injury by intravenous oleic acid (0.25 ml/kg), 5% albumin solution with 1.5 microCi (125)I-labeled albumin (5 ml/kg) was delivered into both lungs via trachea. Alveolar liquid clearance (ALC), extravascular lung water (EVLW) content and arterial blood gases were measured one hour thereafter. RESULTS: At 24 h after the infusion of oleic acid, the rats developed pulmonary edema and severe hypoxemia, with EVLW increased by 47.9% and ALC decreased by 49.2%. Addition of either 2x10(-3) M amiloride or 5x10(-4) M ouabain to the instillation further reduced ALC and increased EVLW. ALC increased by approximately 63.7% and EVLW decreased by 46.9% with improved hypoxemia in the Terbutaline (10(-4) M) group, compared those in injured rats. A significant negative correlation was found between the increment of EVLW and the reduction of ALC. CONCLUSIONS: Active fluid transport of alveolar epithelium might play a role in the pathogenesis of lung edema in acute lung injury.