Fixing the anesthesia research crisis in Japan.

To explore the current status of anesthesia research activity in Japan, we analyzed the number of abstracts presented at the Japanese Society of Anesthesiologists (JSA) annual meetings by several factors including gender, society branches, and subspecialty categories. The number of abstracts at JSA annual meetings has declined sharply since 2016 with no gender gap. A decrease in the neurological field predated the overall decline, but other subspecialty categories showed a similar decline. Although the Tokyo, Tokai-Hokuriku, and Kyushu branches were responsible for more than half of the reduction, the trend was similar among all branches. In a survey regarding academic activities of university hospital residents and faculty, Ph.D. aspirants' rate was only 20-30%. Residents had never presented an abstract at scientific conferences and never published any papers at nearly 40% and 30% of the university hospitals, respectively. Our survey suggests that junior anesthetists are losing interest in research. Senior faculty and mentors must redouble efforts to embed and encourage research in departments and by anesthetists in training. If a revival of anesthesia research in Japan does not occur then a service only specialty awaits.

The Efficacy and Safety of Dexmedetomidine for Procedural Sedation in Patients Receiving Local Anesthesia Outside the Intensive Care Unit: A Prospective, Double-Blind, Randomized Clinical Phase III Trial in Japan.

BACKGROUND: Few studies (in other countries than the US) have reported on the efficacy and safety of dexmedetomidine for sedation of patients undergoing surgical or medical procedures under local anesthesia without intubation outside the intensive care unit. We performed a randomized, double-blind study in Japan. METHODS: Adult patients were randomly allocated to receive placebo, dexmedetomidine 0.5 µg/kg (DEX 0.5 group), or dexmedetomidine 1.0 µg/kg (DEX 1.0 group) over 10 min. Then, both dexmedetomidine groups received dexmedetomidine 0.2-0.7 µg/kg/h for maintaining an Observer's Assessment of Alertness/Sedation Scale (OAA/S) score of ≤ 4; however, propofol was administered to rescue patients whose score exceeded this value. The primary endpoint was the percentage of patients who did not require rescue propofol to achieve and maintain an OAA/S score of ≤ 4. RESULTS: In total, 162 patients were included in the placebo (n = 53), DEX 0.5 (n = 53), and DEX 1.0 (n = 56) groups. Propofol was not required in significantly more patients in the dexmedetomidine 0.5 and 1.0 µg/kg groups (52.8% and 57.1%, respectively) compared with the placebo group (1.9%) (P < 0.001 for both). Common adverse events were protocol-defined hypotension, respiratory depression and bradycardia. The incidence of bradycardia was significantly higher in the DEX 0.5 (26.4%) and DEX 1.0 (30.4%) groups than in the placebo group (9.4%) (P = 0.041 and P = 0.008, respectively). CONCLUSION: We concluded that a loading dose of 0.5 or 1.0 µg/kg dexmedetomidine followed by infusion at a rate of 0.2-0.7 µg/kg/h provided effective and well-tolerated sedation in patients undergoing surgical or medical procedures under local anesthesia without intubation.Clinical trials.gov identifier: NCT01438931.

Efficacy and safety of remimazolam versus propofol for general anesthesia: a multicenter, single-blind, randomized, parallel-group, phase IIb/III trial.

PURPOSE: This trial was conducted to confirm the non-inferiority of remimazolam versus propofol in the induction and maintenance of general anesthesia in surgical patients. METHODS: Surgical patients (n = 375) were randomized to remimazolam started at 6 or 12 mg/kg/h by continuous intravenous (IV) infusion until the loss of consciousness (LoC), followed by 1 mg/kg/h to be adjusted as appropriate until the end of surgery or IV propofol administered as a slow bolus of 2.0-2.5 mg/kg until LoC followed by 4-10 mg/kg/h until the end of surgery. Efficacy was measured via the combined primary endpoint of no intraoperative awakening/recall, no need for rescue sedatives, and no body movements. Adverse events and adverse drug reactions (ADRs) were monitored for safety. RESULTS: Efficacy rates were 100% in all treatment groups, and the non-inferiority of remimazolam was demonstrated [95% confidence interval (- 0.0487; 0.0250)]. The time to LoC was longer in the remimazolam 6 (p < 0.0001) and 12 mg/kg/h (p = 0.0149) groups versus propofol. The time to extubation was longer in both remimazolam groups versus the propofol group (p ≤ 0.0001). The incidence of ADRs was similar in the remimazolam groups (39.3% and 42.7%, respectively) compared with the propofol group (61.3%). Decreased blood pressure occurred in 20.0% and 24.0% of patients treated with 6 and 12 mg/kg/h remimazolam, respectively, compared with 49.3% of patients receiving propofol. Injection site pain was reported in 18.7% of propofol patients but not in those receiving remimazolam. CONCLUSIONS: This trial demonstrated that remimazolam was well tolerated and non-inferior to propofol with regard to efficacy as a sedative hypnotics for general anesthesia. CLINICAL TRIAL REGISTRATION: This trial is registered with the Japan Pharmaceutical Information Center - Clinical Trials Information (JapicCTI). JapicCTI number: 121973.

Perioperative Factors Associated With Chronic Central Pain After the Resection of Intramedullary Spinal Cord Tumor.

OBJECTIVE: Some patients experience severe chronic pain after intramedullary spinal cord tumor (IMSCT) resection, but the underlying mechanisms have yet to be fully elucidated. We aimed to investigate perioperative factors associated with chronic pain after IMSCT resection. MATERIALS AND METHODS: We analyzed data from a postal survey and the medical records of patients who had undergone IMSCT resection in our institution between 2000 and 2008. Chronic pain was assessed using the Neuropathic Pain Symptom Inventory score, and its associations with factors related to tumor pathology, patient demographics, neurological findings, surgery, anesthesia, and perioperative management were determined. RESULTS: Seventy-eight consecutive patients (55 men and 23 women; age 17 to 79 y) were included in the statistical analysis of the present study. In univariate analyses, sex, body mass index, preoperative tumor-related pain, preoperative nonsteroidal anti-inflammatory drugs, intraoperative hypotension, postoperative corticosteroids, and decrease in Japanese Orthopaedic Association (JOA) scores were found to be associated with postsurgical chronic central pain. Logistic regression analysis identified 3 significant factors: a decline in JOA scores compared with preoperative values (odds ratio [OR], 3.33; 95% confidence interval [CI], 1.18-9.42; P=0.023), intraoperative hypotension (OR, 3.01; 95% CI, 1.02-8.97; P=0.047), and postoperative corticosteroids (OR, 3.21; 95% CI, 1.02-10.09; P=0.046). DISCUSSION: Decline in JOA score, intraoperative hypotension, and postoperative corticosteroids are independently associated with postsurgical chronic central pain. Intraoperative hypotension and the use of postoperative corticosteroids can be avoided or modified during perioperative management. As results from animal studies have indicated that the administration of corticosteroids may intensify chronic pain, further studies in larger cohorts are required to definitively determine the effect of corticosteroids on postsurgical central pain.

Anesthetic management of a patient with Hermansky-Pudlak syndrome undergoing video-assisted bullectomy.

The Hermansky-Pudlak syndrome (HPS) is a rare set of disorders characterized by oculocutaneous albinism, bleeding diathesis, and pulmonary fibrosis, with the latter 2 conditions presenting major challenges in anesthetic management. We report a 53-year-old woman with pulmonary fibrosis secondary to HPS who underwent video-assisted bullectomy to treat recurrent pneumothorax. Preoperative bleeding time and platelet count were within normal limits, but the surgeons had difficulty with continuous oozing from the incision site; the surgical blood loss was 270 mL, which was a relatively large amount for this surgery. Because of her restrictive lung disease, the patient's tidal volume was only 250 mL under pressure-controlled ventilation, with a peak inspiratory pressure of 30 cm H2O and a positive end-expiratory pressure of 5 cm H2O. She also had postoperative respiratory insufficiency, with a partial pressure of arterial CO2 of 112 mm Hg and a pH of 7.08 on arterial blood gas analysis. Then, the patient needed mechanical ventilation for 4 days. In conclusion, patients with HPS require strict respiratory management to support their restrictive pulmonary dysfunction, and, also, we should consider preventive management for hemostasis and adequate analgesia to reduce the patient's work of breathing.

Questionnaire survey on current status of home care and support for patients with hematological diseases.

In order to survey the current status of home care and support for patients with hematological diseases, questionnaires were sent to 3,591 hospitals and home care facilities in Tokyo and surrounding prefectures. The first survey showed that 81.7% of medical staff members at hospitals reported that they had experience with home care and support, but only 24.9% of home care facility staff members had such experience. The second questionnaire, surveying 1,202 personnel, identified four factors hampering successful establishment of home care and support networks for hematological diseases. These included insufficient familial support for patients, difficulty making end of life decisions by family members and patients, limited access to transfusion support, and financial problems.

[Anesthetic management of a neonate with congenital cystic adenomatoid malformation].

We report the anesthetic management of a female neonate with congenital cyst adenoid malformation (CCAM) type III of the lung who underwent the lower right lobe resection 22 days after birth. General anesthesia was induced with propofol and rocuronium. The trachea was intubated with a 3.0 standard tube. Anesthesia was maintained with sevoflurane in an air/oxygen mixture and fentanyl. Intraoperative anesthetic course was uneventful except transient desaturation during lung compression. Immediately, the saturation was restored by interruption of lung compression. One lung ventilation was not necessary in this operation. Postoperative course was uneventful. Patient was discharged home on the 28th postoperative day.

Combination therapy of 15-epi-lipoxin A4 with antibiotics protects mice from Escherichia coli-induced sepsis*.

OBJECTIVES: Inflammation occurs along with infection during sepsis. 15-Epi-lipoxin A4 has protective and resolving effects in experimental models of infection. In this study, we examined the effects of 15-epi-lipoxin A4 combined with antibiotics on Escherichia coli-induced peritonitis. DESIGN: Prospective experimental study. SETTING: University research laboratory. SUBJECTS: Male C57BL/6 mice. INTERVENTIONS: Mice were injected with E. coli to induce peritonitis and were given either 15-epi-lipoxin A4 (1 µg/mouse) or placebo (saline) with antibiotics (ceftazidime). The effects of 15-epi-lipoxin A4 on peritoneal cell populations, bacterial burden, and cytokine production were assessed. Survival rates were observed for up to 7 days. In addition, we examined the effects of 15-epi-lipoxin A4 on peritoneal macrophages stimulated with lipopolysaccharide, CpG DNA, or live E. coli. MEASUREMENTS AND MAIN RESULTS: Treatment with 15-epi-lipoxin A4 significantly reduced the number of neutrophils in the peritoneum, inhibited production of cytokines and chemokines, and decreased bacterial load in the serum. Combined treatment of 15-epi-lipoxin A4 with antibiotics significantly improved survival in E. coli-infected mice. 15-Epi-lipoxin A4 also attenuated the production of interleukin-6 and tumor necrosis factor-α by lipopolysaccharide- or CpG DNA-stimulated peritoneal macrophages. Furthermore, 15-epi-lipoxin A4 combined with antibiotics synergistically reduced the production of interleukin-6 and tumor necrosis factor-α by peritoneal macrophages stimulated with live E. coli. CONCLUSIONS: 15-Epi-lipoxin A4 combined with antibiotics attenuated systemic inflammation, inhibited bacteria dissemination, and improved survival in E. coli-infected mice. The reduced production of interleukin-6 and tumor necrosis factor-α by peritoneal macrophages suggested that 15-epi-lipoxin A4 blocked the initial proinflammatory response. Taken together, these data suggested that 15-epi-lipoxin A4 combined with antibiotics was beneficial in regulating the proinflammatory response in sepsis without exacerbating infection.

[Efficacy and safety of sugammadex (Org 25969) in reversing moderate neuromuscular block induced by rocuronium or vecuronium in Japanese patients].

BACKGROUND: Efficacy and safety of sugammadex in reversing neuromuscular block induced by rocuronium or vecuronium were investgated in Japanese patients. METHODS: We studied 98 Japanese patients undergoing surgery requiring general anesthesia. Patients were allocated randomly to receive intubation dose of rocuronium or vecuronium. During surgery, patients received additional doses of rocuronium or vecuronium for maintenance of moderate block. At T2 reappearance sugammadex 0-4.0 mg . kg-1 was administered. The neuromuscular block was monitored with acceleromyography using TOF stimuli. Sevoflurane was administered to all treatment groups after intubation. RESULTS: For the rocuronium-induced neuromuscular block, the mean recovery time of the T4/T1 ratio to 0.9 decreased from 82.1 min in the placebo group to 1.8 min in the 4.0 mg . kg-1 sugammadex group. For the vecuronium-induced neuromuscular block, it decreased from 83.2 min in the placebo group to 2.1 min in the sugammadex 4.0 mg . kg-1 group. Plasma concentrations of sugammadex were approximately dose proportional over the dose range of 0.5 to 4.0 mg . kg-1 and independent of the neuromuscular blocking agents used. No clinical evidence of recurarization or residual curarization was observed. CONCLUSIONS: The efficacy and safety of sugammadex were confirmed in Japanese surgical patients.

[Efficacy and safety of sugammadex (Org 25969) in reversing deep neuromuscular block induced by rocuronium or vecuronium in Japanese patients].

BACKGROUND: Efficacy and safety of sugammadex in reversing neuromuscular block induced by rocuronium or vecuronium were investgated in Japanese patients. METHODS: We studied 99 Japanese patients undergoing surgery requiring general anesthesia. Patients were allocated randomly to receive intubation dose of rocuronium or vecuronium. During surgery, patients received additional dose of rocuronium or vecuronium for maintenance of deep block. At 1-2 PTC, 0.5-8.0 mg . kg-1 of sugammadex was administered. The neuromuscular block was monitored with acceleromyography using TOF stimuli. Sevoflurane was administered to all treatment groups after intubation. RESULTS: For the rocuronium-induced neuromuscular block, the mean recovery time of the T4/T1 ratio to 0.9 decreased from 66.9 min in the sugammadex 0.5 mg kg-1 group to 1.3 min in the sugammadex 8.0 mg kg-1 group. For the vecuronium-induced neuromuscular block it decreased from 79.5 min in the sugammadex 0.5 mg . kg-1 group to 2.9 min in the sugammadex 8.0 mg . kg-1 group. No clinical evidence of recurarization or residual curarization was observed. CONCLUSIONS: The efficacy and safety of sugammadex were confirmed in Japanese surgical patients for reversal from deep block.

Increased prothrombotic property as a risk factor of acute kidney injury after surgical repair of abdominal aortic aneurysm: a prospective observational study.

BACKGROUND: Acute kidney injury (AKI) is one of the major morbidities after surgical repair of abdominal aortic aneurysm (AAA); however, precise pathogenesis of this morbidity has not been well determined. Since prothrombotic coagulation abnormality may precede organ dysfunction in systemic inflammatory state, we examined the kinetics of von Willebrand factor (VWF) and a disintegrin-like metalloprotease with thrombospondin type 1 motif 13 (ADAMTS13), a cleaving enzyme of VWF, on the development of AKI after AAA surgery. METHODS: The kinetics of ADAMTS13 and VWF were examined in ten patients who underwent surgical repair of AAA. The changes in plasma neutrophil gelatinase-associated lipocalin (NGAL), a novel biomarker for AKI, and serum creatinine concentration were also examined at four points until seventh postoperative day (POD). Clinical diagnosis of AKI was based on the change in serum creatinine concentration and urine output according to Acute Kidney Injury Network (AKIN) criteria. RESULTS: ADAMTS13 activity was significantly lower than normal level before the surgery and showed a trend of decrease toward 3POD. The VWF/ADAMTS13 ratio showed a significant increase on 1POD, which persisted until 7POD. None of patents was diagnosed as AKI based on AKIN criteria, although two patients received furosemide and/or carperitide therapy because of decreased urine output less than 0.5 ml/kg/h for several hours in ICU. Plasma NGAL showed a trend to increase after the surgery, which was significant on 3POD. The change in plasma NGAL was significantly correlated with VWF/ADAMTS13 ratio (P < 0.01). CONCLUSIONS: This study has shown that patients undergoing AAA surgery were prothrombotic after the surgery because of high VWF/ADAMTS13 ratio. Correlation between VWF/ADAMTS13 ratio and NGAL might indicate contribution of thrombotic event to subclinical AKI in the patients undergoing AAA surgery.

Symptoms overlooked in hospitalized cancer patients: Impact of concurrent symptoms on oversight [corrected] by nurses.

OBJECTIVE: Physical and psychological symptoms in cancer patients are frequently overlooked by medical staff. However, little is known regarding the potential impacts of concurrent physical and psychological symptoms on the overlooking of other symptoms. The aim of this study was to examine the impact of concurrent symptoms on the overlooking of other symptoms in cancer inpatients. METHOD: A total of 255 cancer inpatients in the general wards of one university hospital, who were referred to the palliative care team, were included. On the day of referral, nurses and patients were independently assessed for the presence of the following eight symptoms: pain, fatigue, nausea and vomiting, shortness of breath, lack of appetite, dry mouth, sleep problems, and distressed feelings. The presence of delirium was also separately assessed by nurses and psychiatrists on the team. A total of nine symptoms detected by nurses and those reported by patients or psychiatrists were compared, and logistic regression analysis was performed to identify the variables associated with the overlooking of these symptoms. RESULTS: The most frequently reported symptom was pain (76.5%), followed by distressed feelings (49.8%), sleep problems (34.1%), and delirium (25.1%). The proportion of those overlooked was more than one quarter (25.0-63.6%) for all symptoms except pain (12.8%). Significant associations were found between the overlooking of shortness of breath and concurrent delirium (odds ratio [OR] = 110.9); the overlooking of sleep problems and concurrent lack of appetite (OR = 9.1); and the overlooking of distressed feelings and concurrent dry mouth (OR = 27.7). No patient demographic characteristic was associated with the overlooking of any other symptoms. SIGNIFICANCE OF RESULTS: The presence of some specific concurrent symptoms is likely to lead to the overlooking of other symptoms in cancer inpatients by nurses. Comprehensive assessments of physical and psychological symptoms in daily clinical practice are needed.

Safety and efficacy of dexmedetomidine for long-term sedation in critically ill patients.

PURPOSE: We evaluated the safety and efficacy of long-term administration of dexmedetomidine in patients in the intensive care unit (ICU). Primary endpoint was the incidence of hypotension, hypertension, and bradycardia. Secondary endpoints were withdrawal symptoms, rebound effects, the duration of sedation with Richmond Agitation-Sedation Scale (RASS) ≤ 0 relative to the total infusion time of dexmedetomidine, and the dose of additional sedatives or analgesics. METHODS: Dexmedetomidine 0.2-0.7 µg/kg/h was continuously infused for maintaining RASS ≤ 0 in patients requiring sedation in the ICU. Safety and efficacy of short-term (≤ 24 h) and long-term (>24 h) dexmedetomidine administration were compared. RESULTS: Seventy-five surgical and medical ICU patients were administered dexmedetomidine. The incidence of hypotension, hypertension, and bradycardia that occurred after 24 h (long-term) was not significantly different from that occurring within 24 h (short-term) (P = 0.546, 0.513, and 0.486, respectively). Regarding withdrawal symptoms, one event each of hypertension and headache occurred after the end of infusion, but both were mild in severity. Increases of mean arterial blood pressure and heart rate after terminating the infusion of dexmedetomidine were not associated with the increasing duration of its infusion. The ratio of duration with RASS ≤ 0 was ≥ 85 % until day 20, except day 9 (70 %) and day 10 (75 %). There was no increase in the dose of additional sedatives or analgesics after the first 24-h treatment period. CONCLUSIONS: Long-term safety of dexmedetomidine compared to its use for 24 h was confirmed. Dexmedetomidine was useful to maintain an adequate sedation level (RASS ≤ 0) during long-term infusion.

[Perioperative anticoagulant therapy in a patient with congenital antithrombin III deficiency undergoing posterior spinal fusion].

A 22-year-old female was scheduled to undergo posterior thoracolumbar spinal fusion. She had been diagnosed with congenital antithrombin III (AT-III) deficiency by the onset of pulmonary embolism and deep vein thrombosis after the first operation at the age of 18. Thereafter she had taken warfarin, 5 mg daily, until 4 days before the surgery. Preoperatively, we administered AT-III products to regulate AT-III activity. The posterior spinal fusion was performed successfully without surgical complications. Postoperatively, we continued administration of AT-III products to maintain AT-III activity above 75%. We also used low dose unfractionated heparin with AT-III by continuous intravenous infusion. Heparin was administered with dose adjustment to achieve a target activated partial thromboplastin time of 45 to 60 seconds. After the activated partial thromboplastin time was stabilized in the target range, we started warfarin therapy (target international normalized ratio, 1.5 to 2.5) on postoperative day 16 and stopped administration of heparin on postoperative day 19. There was no thrombosis complications during the perioperative period. Good anticoagulant management was achieved in a patient with congenital AT-III deficiency undergoing posterior spinal fusion.

[Anesthetic management of a patient with severe aortic stenosis undergoing spine surgery].

An 87-year-old man with severe aortic stenosis (AS), refusing aortic valve surgery, was scheduled to undergo posterior spinal fusion. According to American College of Cardiology/American Heart Association (ACC/AHA) 2008 Guideline, aortic valve surgery is recommended before non-cardiac surgery in a patient with severe AS. Several reports have noted that non-cardiac surgery could be performed safely with careful anesthetic management by adjusting left ventricular preload and systemic arterial pressure, and avoiding tachycardia. We used pulmonary artery catheter to estimate left ventricular preload, which is an especially essential factor for maintaining cardiac output. Transesophageal echocardiography has been proved to be superior to pulmonary artery catheter for evaluating left ventricular preload. However, it is difficult to perform in the prone position. Although pulmonary artery wedge pressure (PAWP) is influenced in prone position due to the chest compression, PAWP combined with cardiac index and their responsiveness to fluid administration is valuable in hemodynamic management in a patient with severe AS.

Reversal with sugammadex in the absence of monitoring did not preclude residual neuromuscular block.

BACKGROUND: In Japan, routine clinical care does not normally involve the use of a monitoring device to guide the administration of neuromuscular blocking drugs or their antagonists. Although most previous reports demonstrate that sugammadex offers more rapid and reliable antagonism from rocuronium-induced neuromuscular blockade, this advantage has not been confirmed in clinical settings when no neuromuscular monitoring is used. In this multicenter observational study, we sought to determine whether sugammadex reduces the incidence of postoperative residual weakness compared with neostigmine when the administration of rocuronium and its antagonists is not guided by neuromuscular monitoring. METHODS: This study was conducted in two 5-month periods that preceded and followed the introduction of sugammadex into clinical practice in Japan. Five university-affiliated teaching hospitals participated in this study. Neostigmine was used to antagonize rocuronium-induced neuromuscular blockade in the first phase, and sugammadex was used in the second phase. The timing and doses of rocuronium, neostigmine, and sugammadex were determined by the attending anesthesiologists without the use of neuromuscular function monitoring devices. To ascertain the incidence of postoperative residual neuromuscular weakness, the train-of-four ratio (TOFR) was determined acceleromyographically after tracheal extubation. Since our practice also does not usually involve calibration and normalization of accelerographic responses, both TOFR <0.9 and TOFR <1.0 were used as the criteria for defining postoperative residual weakness. RESULTS: In the first phase, 109 patients received neostigmine (average dose 33 µg/kg) and 23 patients were considered (by clinical criteria) to have adequate recovery and did not receive neostigmine (spontaneous recovery group). In the second phase, 117 patients received sugammadex (average dose 2.7 mg/kg) for antagonism of rocuronium-induced blockade. The incidence (95% confidence interval) of TOFR <0.9 under spontaneous recovery, after neostigmine, and after sugammadex, was 13.0% (2.8%-33.6%), 23.9% (16.2%-33.0%), and 4.3% (1.7%-9.4%), respectively. The incidence (95% confidence interval) of TOFR <1.0 in these groups was 69.6% (47.1%-86.6%), 67.0% (57.3%-75.7%), and 46.2% (36.9%-55.6%), respectively. The use of sevoflurane in the neostigmine group and the short interval between the administration of the last doses of rocuronium and sugammadex were associated with a higher incidence of postoperative residual weakness. CONCLUSIONS: This study demonstrated that the risk of TOFR <0.9 after tracheal extubation after sugammadex remains as high as 9.4% in a clinical setting in which neuromuscular monitoring (objective or subjective) was not used. Our finding underscores the importance of neuromuscular monitoring even when sugammadex is used for antagonism of rocuronium-induced neuromuscular block.

Atrial natriuretic peptide reduces hepatic ischemia-reperfusion injury in rabbits.

PURPOSE: Atrial natriuretic peptide (ANP) has been known to be protective against hepatic ischemia/reperfusion injury. The purpose of this study was to verify the hypothesis that ANP conserves microvascular circulation and reduces ischemia-reperfusion injury in the in vivo rabbit model. METHODS: With IRB approval, 30 male Japanese white rabbits under pentobarbital anesthesia were studied. These animals were randomly assigned to the following three groups (n = 10 each): control, ANP, and sham group. Animals in the ANP group received continuous infusion of ANP at 0.1 µg/kg/min throughout the study period. Animals in control and ANP groups underwent 90 min of partial hepatic ischemia by clamping the right hepatic artery and portal vein. Descending aortic blood flow (AoF) was monitored with a transit-time ultrasound flowmeter. Hepatic tissue microvascular blood flow (HTBF) at both right (ischemic) and left (nonischemic) lobe was intermittently evaluated with the hydrogen clearance method. After 180 min of reperfusion, hepatic injury was determined with serum AST and ALT. Galactose clearance of reperfused right lobe was also measured as an indicator of hepatic metabolic function. Histopathological change and the number of apoptotic hepatocytes were also evaluated. RESULTS: Systemic hemodynamic data including mean arterial pressure, heart rate, and AoF did not differ among the three groups during the study period. ANP attenuated ischemia-induced right HTBF decrease. ANP also suppressed histopathological degeneration, apoptosis, and decline in galactose clearance after reperfusion. CONCLUSIONS: ANP attenuated hepatic microvascular dysfunction and hepatocyte injury after reperfusion without significant hemodynamic change.

A general anaesthetic propofol inhibits aquaporin-4 in the presence of Zn²âº.

AQP4 (aquaporin-4), a water channel protein that is predominantly expressed in astrocyte end-feet, plays an important role in the brain oedema formation, and is thereby considered to be a potential therapeutic target. Using a stopped-flow analysis, we showed that propofol (2,6-diisopropylphenol), a general anaesthetic drug, profoundly inhibited the osmotic water permeability of AQP4 proteoliposomes in the presence of Zn²âº. This propofol inhibition was not observed in AQP1, suggesting the specificity for AQP4. In addition, the inhibitory effects of propofol could be reversed by the removal of Zn²âº. Other lipid membrane fluidizers also similarly inhibited AQP4, suggesting that the modulation of protein-lipid interactions plays an essential role in the propofol-induced inhibition of AQP4. Accordingly, we used Blue native PAGE and showed that the profound inhibition caused by propofol in the presence of Zn²âº is coupled with the reversible clustering of AQP4 tetramers. Site-directed mutagenesis identified that Cys²5³, located at the membrane interface connecting to the C-terminal tail, is responsible for Zn²âº-mediated propofol inhibition. Overall, we discovered that propofol specifically and reversibly inhibits AQP4 through the interaction between Zn²âº and Cys²5³. The findings provide new insight into the functional regulation of AQP4 and may facilitate the identification of novel AQP4-specific inhibitors.