Beneficial Role of Hydrogen Sulfide in Renal Ischemia Reperfusion Injury in Rats

PURPOSE: Hydrogen sulfide (H2S) is an endogenous gaseous molecule with important physiological roles. It is synthesized from cysteine by cystathionine γ-lyase (CGL) and cystathionine β-synthase (CBS). The present study examined the benefits of exogenous H2S on renal ischemia reperfusion (IR) injury, as well as the effects of CGL or CBS inhibition. Furthermore, we elucidated the mechanism underlying the action of H2S in the kidneys. MATERIALS AND METHODS: Thirty male Sprague-Dawley rats were randomly assigned to five groups: a sham, renal IR control, sodium hydrosulfide (NaHS) treatment, H2S donor, and CGL or CBS inhibitor administration group. Levels of blood urea nitrogen (BUN), serum creatinine (Cr), renal tissue malondialdehyde (MDA), and superoxide dismutase (SOD) were estimated. Histological changes, apoptosis, and expression of mitogen-activated protein kinase (MAPK) family members (extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38) were also evaluated. RESULTS: NaHS attenuated serum BUN and Cr levels, as well as histological damage caused by renal IR injury. Administration of NaHS also reduced oxidative stress as evident from decreased MDA, preserved SOD, and reduced apoptotic cells. Additionally, NaHS prevented renal IR-induced MAPK phosphorylation. The CGL or CBS group showed increased MAPK family activity; however, there was no significant difference in the IR control group. CONCLUSION: Exogenous H2S can mitigate IR injury-led renal damage. The proposed beneficial effect of H2S is, in part, because of the anti-oxidative stress associated with modulation of the MAPK signaling pathways.

Comparison of the analgesic efficacy of oxycodone and fentanyl after dental surgery

BACKGROUND: Oxycodone is a strong m-opioid receptor agonist and has a longer duration of analgesic effect than fentanyl. We compared the use of an intravenous (IV) bolus of oxycodone and fentanyl for postoperative analgesic efficacy after dental surgery. METHODS: Patients underwent surgical extraction under general anesthesia. We prospectively enrolled patients who had received IV oxycodone (n = 36, 0.05 mg/kg) and fentanyl (n = 36, 1 mg/kg) 10 minutes before the end of surgery. The recovery profiles (hemodynamic variables, pain score, postoperative nausea and vomiting, sedation scale, and adverse events) were recorded for 1 hour in the post-anesthetic care unit (PACU) and at 6 hours after surgery. RESULTS: Under a potency ratio of 50:1 (oxycodone:fentanyl), time to spontaneous ventilation was significantly longer in the oxycodone group (8.1 ± 2.8 min vs. 6.9 ± 1.8 min, P = 0.021). The overall pain scores were significantly lower in the oxycodone than in the fentanyl group (P < 0.001), and the oxycodone group had significantly fewer additional analgesic requirements in the PACU than the fentanyl group (8.3% vs. 27.8%, P = 0.032). The incidence of postoperative nausea and sedation were comparable in both groups. No opioid-related adverse event was identified. CONCLUSIONS: In dental surgery, 0.05 mg/kg IV oxycodone had a longer-lasting analgesic effect than that of 1 µg/kg IV fentanyl, and could reduce total opioid consumption without increasing side effects. Patients experienced satisfactory analgesia postoperatively; thus, oxycodone is an effective opioid analgesic for acute postoperative pain relief.

Regional anesthetic management of elderly patients

In general, elderly patients are less able to respond to perioperative stress and are more likely to suffer from postoperative complications and even death because of the decline in their functional organ reserve. Although no definitive evidence indicates that regional anesthesia is superior to general anesthesia in terms of the long-term prognosis in the elderly, regional anesthesia appears to be beneficial in many ways because it reduces bleeding during surgery, the stress response, and the incidence of thromboembolic complications, as well as facilitating excellent postoperative pain control. However, some issues specific to the elderly should also be considered. Age-related anatomical changes in elderly patients may make it difficult to perform epidural and spinal anesthesia, and physiologic and pharmacodynamic responses to local anesthetics may change with age. Elderly patients also show a greater extent of sensory and motor block, and are at a greater risk of hypotension after epidural and spinal block. In order to provide optimal anesthetic care and to facilitate a rapid recovery and improved outcomes in elderly patients, clinicians must have a better understanding of age-related changes when regional anesthesia is administered. Additionally, tailored anesthetic techniques should be used, as well as good perioperative care, in accordance with the type of surgery and the individual physical status of elderly patients.

The use of EMLA cream reduces the pain of skin puncture associated with caudal block in children / 대한마취과학회지

BACKGROUND: Caudal block is a popular regional anesthesia in children undergoing infraumbilical surgeries including inguinal hernia repair and orchiopexy. We evaluated the efficacy of eutectic mixture of local anesthetic (EMLA) cream for reducing needle insertion pain during caudal block in pediatric patients. METHODS: Forty-one children between the ages of 13 months and 5 years undergoing infraumbilical surgery were randomized to receive either topical EMLA or placebo cream over the sacral hiatus one hour before caudal block. All children were assessed with the Multidimensional Assessment Pain Scale (MAPS) at the following time points. T0: arrival at the operation room; T1: just before needle insertion; T2: immediately after needle insertion into the sacral hiatus. The need for sevoflurane inhalation due to procedural pain response was also assessed at the same time as MAPS assessment. RESULTS: MAPS scores were significantly lower in the EMLA group compared with the placebo group at T2 (P = 0.001). Moreover, need for sevoflurane inhalation due to procedural pain response was significantly lower in the EMLA group compared with the control group at T2 (P < 0.001). CONCLUSIONS: We suggest that pretreatment with EMLA cream over the sacral hiatus before caudal block has significant advantages in alleviating procedure pain during caudal block in children.

Intraoperative electrical burn caused by stainless tube tree with noncontact electrosurgical ground: A case report

Noncontact electrosurgical ground is recently developed to provide adequate electrical return to electric surgical unit without direct contact to the patient. It provides full and safe electrical return without direct contact of patient due to oscillating, high frequency nature of the current flow and large surface of pad. It is useful in burn surgery and effective to prevent burn by improper placements of the grounding pad. But it can induce current to conducting object with direct contact. Current induced in conductive materials can produce heat to make burns. We present a patient with full-thickness burn in left third finger which was resulted from current through stainless steel tube tree on the operating table during surgery. The stainless tube tree was placed on noncontact electrosurgical ground which was covered with plastic sheet and linen sheet. Staff in operating room should be educated and remain vigilant for electrical burns caused by metallic object on noncontact grounding pad.

Forearm extravasation injury during robot-assisted low anterior resection / 대한마취과학회지

No abstract available.

Forearm extravasation injury during robot-assisted low anterior resection / 대한마취과학회지

No abstract available.

Predictive Factors for Lymph Node Metastasis in Signet Ring Cell Gastric Cancer and the Feasibility of Endoscopic Submucosal Dissection

PURPOSE: Endoscopic submucosal dissection has recently been practiced on a differentiated type of early gastric cancer. However, there is no clear evidence for endoscopic treatments of signet ring cell carcinoma. The aim of this study is to identify the predictive clinicopathological factors for lymph node metastasis in signet ring cell carcinoma for assisting endoscopic submucosal dissection trials. MATERIALS AND METHODS: A total of 186 patients with early signet ring cell carcinoma who underwent radical curative gastrectomy between January 2001 and September 2009 were enrolled in this study. Retrospective reviews of their medical records are being conducted. Several clinicopathologic factors were being investigated in order to identify predictive factors for lymph nodes metastasis: age, gender, tumor size, type of operation, tumor location, gross type, ulceration, Lauren's classification, depth of invasion, and lymphatic invasion. RESULTS: The lymph node metastasis rate for signet ring cell carcinoma was 4.3% (n=8). Of the 186 lesions with early signet ring cell carcinoma, 91 (48.9%) tumors were larger than 15 mm in size and 40 (21.5%) showed submucosal invasions in the resection specimens. In multivariate analysis, only the lymphatic invasion (P<0.0001) showed an association with lymph node metastasis. To evaluate cutoff values for tumor sizes in the presence of lymph node metastasis, early signet ring cell carcinomas with lymphatic invasions were excluded. In the absence of lymphatic invasion, mucosal cancer with tumor sizes <15 mm had no lymph node metastasis. CONCLUSIONS: Endoscopic submucosal dissection can be performed on patients with early signet ring cell carcinoma limited to the mucosa and less than 15 mm.

Medical environment and drug abuse among physicians: current state and problems in Korea

Currently, the number of reports of propofol abuse in the general population and among physicians has increased, arousing public concerns about drug abuse. It is especially easy for physicians to access various drugs, and thus they are prone to abuse drugs. However, the data on physicians' drug abuse in the Republic of Korea remains insufficient. In this article, we estimated the state of current drug abuse among the Korean general population and the assumed rate and tendency toward drug abuse among physicians based on published data. The current prevalence of drug abuse in Korea is around 4%, and the physicians' rate may not differ from that of the general population. According to the data on drug-related crime in Korea, 1% of such crimes are associated with medical personnel. Opioids are used more frequently by medical personnel than the general population (6.2% vs. 18.1%). Even though drug abuse is commonly related to personality problems and comorbid psychological disorders, social and environmental factors are also important. Burnout problems due to the stresses of a heavy workload in the hospital with sleep deprivation, rapidly expanding medical knowledge, and increasing government regulations are additional important causes of drug abuse among physicians. However, few studies on drug abuse and physician burnout have been performed in Korea. Although the rate of physicians' drug abuse is similar to that in the general population, the prevalence is disturbing because physicians are responsible for the health and well-being of the general population. Therefore, detailed research about physicians' drug abuse and burnout is needed, and proper solutions to prevent and treat drug abuse should be established.

Risk factors for perioperative respiratory adverse events in pediatric anesthesia; multicenter study

BACKGROUND: Perioperative respiratory adverse events remain a major cause of postoperative morbidity and mortality during pediatric anesthesia. This multicenter study was designed to evaluate the incidence of perioperative respiratory adverse events during elective pediatric surgery and to identify the risk factors for these events. METHODS: Pediatric patients undergoing elective surgery under general anesthesia in 11 hospitals were randomly selected for this prospective, multicenter study. Preanesthetic assessments, anesthetic and surgical conditions were recorded by anesthesiologists in charge. Adverse respiratory events were registered. RESULTS: Eight hundred and twenty-three patients were included. The overall incidence of any perioperative respiratory adverse respiratory event was 15.1%. The incidences of perioperative bronchospasm, laryngospasm, coughing, desaturatioin (oxygen saturation or =2, OR 1.62. CONCLUSIONS: Multiple attempts for airway device insertion, recent URI, induction with intravenous anesthetics, airway related surgery and ASA class > or =2 were associated with increased risk for perioperative respiratory adverse events.

Cardiac arrest with pulseless electrical activity during a robot-assisted distal gastrectomy: A case report

A 59-year-old woman was scheduled to undergo a robot-assisted distal gastrectomy under general anesthesia. During the operation, the vital signs were maintained in normal range. After 7 hours of surgery, the pulse oxymeter graph became flat and the end tidal CO2 concentration suddenly decreased. Palpation of the carotid artery revealed no heart beat but the EKG continued to show sinus rhythm. Pulseless electrical activity (PEA) was diagnosed. An advanced cardiopulmonary life support protocol for PEA was immediately initiated, which included chest compressions and doses of IV cardiovascular drugs. However, in spite of continuous CPR, the heart wasn't recovered from the arrest. We experienced cardiac arrest for pulseless electrical activity during robot-assisted distal gastrectomy.

Effect of superoxide on the development and maintenance of mechanical allodynia in a rat model of chronic post-ischemia pain / 대한마취과학회지

BACKGROUND: Reactive oxygen species and inflammatory responses contribute to the development of neuropathic pain. Superoxide serves to mediate cell signaling processes and tissue injury during inflammation. We examined the effects of superoxide on the development and maintenance of mechanical allodynia, as well as its contribution to central sensitization in a superoxide-rich animal model of neuropathic pain. METHODS: Chronic post-ischemia pain (CPIP) was induced via the left hindpaw ischemia for 3 h, followed by reperfusion. Superoxide dismutase (4,000 U/kg, i.p.) was administered either 5 min before ischemia (BI), 5 min before reperfusion (BR), or 3 days after reperfusion (3AR). Withdrawal thresholds of the four paws were measured to assess the mechanical allodynia and the effects of circulating xanthine oxidase (XO)-mediated superoxide production. In addition, we measured the levels of N-methyl D-aspartate receptor subunit 1 phosphorylation (p-NR1) in the ipsilateral and contralateral spinal cord (L4-6), by Western blotting, to examine the superoxide-mediated central sensitization. Superoxide production was assessed by allopurinol-sensitive, XO-mediated lipid peroxidation of the spinal cord and gastrocnemius muscles. RESULTS: Withdrawal thresholds of forepaws did not vary across the 7 days of testing. In the hindpaws, both ipsilateral and contralateral mechanical allodynia was most attenuated in the BR group, followed by the BI and 3AR groups. The degree of NR1 activation was in contrast to the changes in the withdrawal thresholds. CONCLUSIONS: These data suggest that superoxide is involved in the development and maintenance of mechanical allodynia, particularly via central sensitization in the spinal cord.

Expression and Cellular Localization of Psx Gene in Rat Placenta / 체질인류학회지

Homeobox genes seem to play critical roles in regulating morphogenesis, patterning, organogenesis, and differentiation. They have the conserved sequence that codes the DNA-binding domain called homeodomain. The expression and cellular localization of rPsx mRNA in rat placenta during placental development were examined by in situ hybridization histochemistry at different embryonic stages (Embryonic days 7.5~16.5). rPsx mRNA was first detected in chorionic ectoderm of placenta at E 10.5. This transcript was localized in labyrinth trophoblast and trophoblast giant cells at E 11.5. Hybridization signals were observed in labyrinth trophoblast, spongiotrophoblast, and trophoblast giant cells at E 12.5, E 13.5, and E 14.5. At E 15.5, hybridization signal was detected in labyrinth trophoblast and spongiotrophoblast but not in trophoblast giant cells. Hybridization signal was only detected in labyrinth trophoblast at E 16.5. rPsx mRNA was not detected in decidua and any tissues of the embryo from E 7.5 to E 9.5 of gestations. From these results, a new rPsx homeobox gene is first expressed at E 10.5 and detected in chorionic ectoderm, labyrinth trophblast, spongiotrophoblast and trophoblast giant cells of the placenta. This gene may play a critical role in differentiation and development of trophoblast cells.

Enhanced Expression of Carbonic anhydrase II in Hypokalemic Rat Kidney / 체질인류학회지

A number of acid-base or electrolyte disorders are associated with decreased or increased HCO3- reabsorption in the renal tubules. The present study was to examine the alterations of expression and distribution of Carbonic anhydrase II in the kidneys of normal and potassium-depleted rats using Western blot analysis and immuno-histochemistry. Western blot analysis demonstrated that CA II protein, ~30 kDa at molecular mass, was abundantly expressed in normal group. All potassium-depleted groups showed slightly increased CA II protein compared to normal group. In control group, immunoreactivity of CA II protein was detected in the entire collecting duct. Signal intensity was prominent in the intercalated cells and weak in the principal cells of the cortical collecting ducts. In potassium-depleted groups, the pattern of cellular labeling of CA II protein was identical to that of normal group, but the signal intensity was decreased in cortical collecting duct, markedly increased in the inner stripe of outer medullary and inner medullary collecting ducts, and unchanged in the outer stripe of outer medullary collecting duct. These results suggest that chronic hypokalemia impact the expression pattern of CA II protein depending the portion of the collecting duct.

HOXB13 is co-localized with androgen receptor to suppress androgen-stimulated prostate-specific antigen expression / 대한해부학회지

During the prostate cancer (PCa) development and its progression into hormone independency, androgen receptor (AR) signals play a central role by triggering the regulation of target genes, including prostate-specific antigen. However, the regulation of these AR-mediated target genes is not fully understood. We have previously demonstrated a unique role of HOXB13 homeodomain protein as an AR repressor. Expression of HOXB13 was highly restricted to the prostate and its suppression dramatically increased hormone-activated AR transactivation, suggesting that prostate-specific HOXB13 was a highly potent transcriptional regulator. In this report, we demonstrated the action mechanism of HOXB13 as an AR repressor. HOXB13 suppressed androgen-stimulated AR activity by interacting with AR. HOXB13 did neither bind to AR responsive elements nor disturb nuclear translocation of AR in response to androgen. In PCa specimen, we also observed mutual expression pattern of HOXB13 and AR. These results suggest that HOXB13 not only serve as a DNA-bound transcription factor but play an important role as an AR-interacting repressor to modulate hormone-activated androgen receptor signals. Further extensive studies will uncover a novel mechanism for regulating AR-signaling pathway to lead to expose new role of HOXB13 as a non-DNA-binding transcriptional repressor.

Effect of pretreatment with acetaminophen on withdrawal movements associated with injection of rocuronium: a prospective, randomized, double-blind, placebo controlled study / 대한마취과학회지

BACKGROUND: Withdrawal movement during rocuronium injection is a common, unresolved adverse effect. We aimed to investigate the effect of IV acetaminophen pretreatment on withdrawal movement during rocuronium injection. METHODS: This study enrolled 120 American Society of Anesthesiologists (ASA) I-II patients undergoing general anesthesia. They were randomly assigned to three treatment groups. After occluding venous drainage using a tourniquet on the upper arm, the saline group received 5 ml of 0.9% sodium chloride solution, the lidocaine group received 40 mg of lidocaine, and the acetaminophen group received 50 mg of acetaminophen. During injection of pretreatment drug, pain was assessed on a four-point scale. The tourniquet was released after 120 seconds and anesthesia was performed using thiopental sodium 5 mg/kg followed by rocuronium 0.6 mg/kg. The withdrawal movement was graded on a four-point scale in a double-blind manner. RESULTS: The incidence of pain on pretreatment injection in saline, lidocaine, and acetaminophen groups was 7.7%, 5.1%, and 2.5%, respectively. The incidence of withdrawal movements was 77.5% in saline group, 32.5% in lidocaine group, and 37.5% in acetaminophen group (P < 0.05). CONCLUSIONS: Acetaminophen and lidocaine reduced the incidence of withdrawal movement after rocuronium injection compared with saline.

Continuous positive airway pressure improves the immediate post-extubation airway patency / 대한마취과학회지

BACKGROUND: Endotracheal tube extubation can cause laryngospasm, aspiration, upper airway obstruction and hypoxia. In addition, the risk of pulmonary complication increases during extubation for the patients with a difficult airway or a cervical spine injury. The aim of this study was to exam the effect of continuous positive airway pressure (CPAP) on the post-extubation airway patency and the recovery from anesthesia at the recovery room. METHODS: 30 adult patients who were scheduled for spine surgery were randomly allocated into 2 groups depending on the using of CPAP before extubation. Neuromuscular monitoring was performed via accelomyography. Tracheal extubation was performed at a TOF ratio of 70%. The incidence of spontaneous recovery of respiration, without airway manipulation and hypoxia, at the recovery room was measured for each group. The time to get a PAR score of 10 at the recovery room and the discharge time from the recovery room were checked too. RESULTS: The incidence of spontaneous recovery of respiration without airway manipulation was 67% in the CPAP group, which was significantly greater than that of the control group (13%). Yet there was no difference between the CPAP and control groups for the incidence of hypoxia in the recovery room (13% and 20%, respectively). There were also no differences in the time to get a PAR score of 10 at the recovery room and the discharge time from the recovery room. CONCLUSIONS: CPAP that is applied for tracheal tube extubation improves the immediate post-extubation airway patency, but it does not reduce the recovery room pulmonary complications and the recovery room discharge time.

Contralateral allodynia and central change in the chronic post-ischemic pain model rats / 대한마취과학회지

BACKGROUND: Mirror-image allodynia is a mysterious phenomenon that occurs in association with many clinical pain syndromes including complex regional pain syndromes (CRPS). Underlying mechanisms for the development of such pain are still a matter of investigation. Several studies suggest that activation of the N-methyl-D-aspartate (NMDA) receptor is essential for central sensitization as a base for persistent pain. The aim is to assess whether alteration of NMDA receptor expression correlates with the contralateral allodynia in the chronic post-ischemia pain (CPIP) model rats representing CRPS-Type I. METHODS: Application of a tight-fitting tourniquet for a period of 3 hours before reperfusion produced CPIP in male Sprague-Dawley rats. The mechanical paw withdrawal thresholds to von Frey stimuli (using a dynamic plantar aesthesiometer) were measured as pain indicators in ipsilateral and contralateral hindpaws. Phosphorylation of the NMDA receptor 1 subunit (pNR1), assessed with Western blot, was measured in the contralateral L4-6 spinal cord. RESULTS: Ipsilateral and contralateral mechanical allodynia is present at 4 hours after reperfusion, peaked at 3 days, and continued for 7 days after reperfusion. The relative density of pNR1 of CPIP rats significantly decreased in the contralateral L4-6 spinal cord compared to baseline value (P < 0.05). There was significant correlation between paw withdrawal threshold and the relative density of pNR1 (ipsilateral; R2 = 0.75, P < 0.01, contralateral; R2 = 0.60, P < 0.01). CONCLUSIONS: These data suggest that pNR1 is correlated to the contralateral mechanical allodynia in CPIP rats.

Immunohistochemical Localizaion of Carbonic Anhydrase Isozymes IV and IX in Rat Salivary Gland / 대한해부학회지

This study presents distribution of carbonic anhydrase (CA) isozymes IV and IX, membrane associated forms, and CA I and II, cytoplasmic forms, in rat parotid and submandibular glands using Western blot analysis and immunohistochemical staining. Western blot analysis demonstrated that CAs I, II and IX were found to be abundantly expressed, but CA IV was weakly expressed in parotid gland. Submandibular gland expressed abundant CAs I and II, weak CA IX, and undetectable level of CA IV. In hematoxylin-eosin staining, parotid gland was entirely composed of serous acini and their ducts while submandibular gland was mixed population of serous and mucous lobules. Most of lobules (submandibular gland proper type) contained mostly serous acini and their ducts with granular convoluted duct. Some lobules (sublingual gland type) contained mostly mucous acini with serous demilune and their ducts without granular convoluted duct. In parotid gland, CAs IV and IX were immunolocalized in duct cells and not in serous acinar cells. Immunoreactivity for CAs I and II was also detectable in duct cells. Serous acinar cells were positive for CA II, and negative for CA I. In submandibular gland, CAs IV and IX were immunolocalized in duct cells but not in acinar cells of both types of lobules. Immunoreactivity for CAs I and II was also detectable in duct cells of both types of lobules. Cells of serous acini and serous demilune were positive for CA II, and negative for CA I. Mucous cells were negative for both CAs I and II. These results demonstrate the distribution of CA isoenzymes in parotid and submandibular glands of the rat, and suggest CAs IV and IX as well as CAs I and II are related to electrolytes metabolism of saliva in duct cells.

Alterations of Aquaporin mRNA and Protein Expression in Hypokalemic Rat Kidney / 대한해부학회지

There has been a general agreement that potassium depletion causes metabolic alkalosis and substantial morphological changes in kidney structure, and is associated with renal functional abnormalities, including a decrease in urinary concentrating ability. The present study was to examine the alterations of expression and distribution of AQP-1, 2, 3 and 4 mRNAs and proteins in the kidneys of normal and K-depleted rats using RT-PCR, Western blot analysis, and immunohistochemistry. Predicted size of AQP-1, 2, 3, and 4 mRNAs was 119, 822, 539, and 642 bp, respectively. AQP-1 mRNA expression was gradually decreased in K-depleted rats, particularly LK 2W. AQP-2, 3 mRNAs were markedly decreased in K-depleted rats. AQP-4 mRNA expression was markedly increased in K-depleted rats, particularly LK 2W. Western blot analysis demonstrated that AQP-1 protein expression was only decreased in LK 3D and others were comparable with normal rat. AQP-2, 3 proteins expression was markedly decreased in K-depleted rats, compared with normal rat. But, AQP-4 protein expression was markedly increased in K-depleted rats, particularly LK 3W. In immunohistochemistry, AQP-1 was detected in the apical membranes of proximal tubules and thin limb of Henle loop. In potassium-depleted kidney, the pattern of cellular labeling and signal intensity of AQP-1 protein is identical to that of normal rat. AQP-2 was detected in apical region and cytoplasm of the principal cells of entire collecting duct. In potassium-depleted kidney, the pattern of cellular labeling of AQP-2 protein is identical to that of normal rat, but signal intensity is markedly decreased. AQP-3 was detected in the bosolateral plasma membrane of principal cells of entire collecting duct. In potassium-depleted kidney, the pattern of cellular labeling of AQP-3 protein is identical to that of normal rat, but signal intensity is markedly decreased. AQP-4 was detected in the bosolateral plasma membrane of principal cells of entire collecting duct. In potassium-depleted kidney, the pattern of cellular labeling of AQP-4 protein is identical to that of normal rat, but signal intensity is markedly increased in outer and inner medullary collecting ducts. In summary, these results demonstrate that chronic hypokalemia shows the different expression pattern of AQP-1, 2, 3, and 4 mRNAs and proteins. These results suggest that a decrease in urinary concentrating ability is a major factor in the decreased AQP-2, 3 expression, and that is partly compensated by increased expression of AQP-4.