The Effect of Treatment With Aminoguanidine, an Advanced Glycation End Product Inhibitor, on Streptozotocin-Induced Diabetic Rats and Its Effects on Physiological and Renal Functions.

BACKGROUND/AIM: Diabetes is a multifactorial syndrome that affects the functioning of the renin-angiotensin system (RAS). The role of advanced glycation end products (AGEs) in diabetes is well known. In the present study, we hypothesized that the prevention of AGE accumulation or abrogation of AGE synthesis using an AGE inhibitor, aminoguanidine (AG), in streptozotocin (STZ)-induced diabetic animal models would affect the progression of diabetes and its related complications. We determined the effects of aminoguanidine (AG), an AGE inhibitor, in STZ-induced diabetic rats by determining various indices of RAS and renal functions. Additionally, we also investigated the effect of the drug, AG, on various hemodynamic and physiological functions in the body of the animals. METHODS: Male Sprague Dawley rats weighing 200-250 g were assigned to four groups (n = 4-6): Vehicle, Vehicle+AG, STZ-induced, and STZ-induced+AG rats. Type 1 diabetes was induced by a single intraperitoneal (IP) injection of streptozotocin (55 mg/kg) dissolved in sodium citrate buffer. The control groups (Vehicle) were injected with buffer. The blood glucose levels were measured after 48 hours, and animals with blood glucose levels > 300 mg/dL were included in the study. Blood glucose levels in the vehicle rats were also determined to ensure non-diabetic conditions. After confirmation, AG was administrated at a dose of 1 g/L in drinking water for two weeks. Urine was collected to measure the glomerular filtration rate (GFR), and the immune reactivity for AT1 and AT2 proteins was analyzed by immunoblotting. Data were expressed as mean ± standard error of the mean (SEM), and a p-value < 0.05 was considered statistically significant. RESULTS: Diabetic rats had a significant drop in body weight, accompanied by increased food and water consumption. The diabetic rats exhibited significantly increased urine flow and GFR. These phenotypes were significantly or considerately reversed by AG treatment in the STZ+AG-treated diabetic rats. Aminoguanidine prevented the increase in blood sugar levels compared to STZ-induced diabetic rats alone (295.9 ± 50.69 versus 462.3 ± 18.6 mg/dL (p < 0.05)). However, it did not affect the glomerular filtration rate (GFR) and glomerular damage, as assessed by the renal histopathological studies. The STZ-induced diabetic rats had an increased sodium excretion (3.24 ± 0.40 mmol) and significantly increased expression of the AT2 receptor and that of the AT1 receptor, which was slightly reversed by the treatment with AG. Treatment with AG decreased sodium excretion (2.12 ± 0.63, as compared to the diabetic rats). These rats also had modestly decreased expression of the AT2 receptor (0.99 ± 0.07 versus 1.12 ± 0.08, as compared to the STZ-induced diabetic rats), while the AT1 receptors showed a slight increase in the STZ+AG-treated rats compared to the STZ-induced diabetic rats (1.1 ± 0.19 versus 1.08 ± 0.12). CONCLUSION: This study highlights the action of the drug AG in not exacerbating any damage in diabetic rats. Employing AG as a pharmacological intervention to prevent an increase in blood sugar adds a new dimension to controlling increased blood sugar and preventing diabetic complications. The employability and pharmacological intervention of the drug AG, in diabetes, therefore, need a renewed and further investigation.

Prevalence of chronic pain in Pakistan - a national survey.

OBJECTIVE: To assess the prevalence of chronic pain, its physical and psychosocial impact on daily life, and the various therapies adopted to alleviate pain. METHODS: The cross-sectional population-based telephonic survey was conducted from May to July 2021 at Shaukat Khanum Memorial Cancer Hospital, Lahore, Pakistan, and comprised patients of either gender aged at least 18 years suffering from chronic pain who visited the institutional laboratory collection centres. In the first phase, people who were suffering from chronic pain were screened, while in the second phase, data was collected using a detailed questionnaire exploring pain history, treatment and its effects. The data was compiled and analysed using Antlere's AI based software. RESULTS: Of the 4,801 patients contacted, 757(15.75%) were suffering from chronic pain. A total of 201(20%) subjects reported that their pain score was 5/10 on the numerical rating scale. Back pain was the major complaint (183, 18%) among the subjects. Of the total, 335(44.25%) were having active treatment, and 226 (67%) of them said the medication was effective. Overall, 706 (93%) patients had never visited a pain management specialist. Furthermore, 252 (33%) participants were diagnosed with depression, and 106 (14%) patients said that they were suicidal at some point in life. CONCLUSIONS: .The survey observed that a high percentage of unawareness existed on pain management among the Pakistani citizens.

Biochemical markers in the pathogenesis of preeclampsia: novel link between placental growth factor and interleukin-6.

Preeclampsia (PE) is a multisystem disorder of pregnancy characterized by sudden onset of hypertension and proteinuria. The appearance and diagnosis of the disease remain elusive and the only treatment is the termination of pregnancy. The onset of the disease is preceded by a shift in the balance of the angiogenic and antiangiogenic proteins in the maternal circulation. We surmised that the assessment of the levels of these proteins during pregnancy could lead to a proper diagnosis of the disease. In this study, we determined the levels of angiogenic and antiangiogenic proteins and IL-6 in maternal circulation during normotensive and hypertensive pregnancy, including PE. Serum isolated from pregnant women during antenatal visits was used to determine the concentrations of these proteins. The levels of antiangiogenic proteins, sFlt-1 and sEng, were higher in hypertensive disorders [gestational hypertension (GH), mild PE, and PE] of pregnancy and were significantly higher for PE than for GH. The levels of sFlt-1 and sEng were higher in PE samples compared to those in GH and NT samples. These proteins may have contributed to increased blood pressure. The levels of PlGF were decreased in pregnant women having GH, mild PE, and PE. The levels of the inflammatory intermediate, IL-6, were increased in PE samples compared to those in the GH and normotensive samples. The evaluation of the altered levels of antiangiogenic and angiogenic proteins can be useful for diagnosis of PE.

Dynamic Hip Screw Fixation Vs. Proximal Femur Nail For Unstable Per-Trochanteric Fractures: A Comparative Analysis Of Outcomes And Complications.

BACKGROUND: There are various implant choices to fix unstable per- trochanteric fractures. The aim of this study was to compare the outcomes of dynamic hip screw and proximal femur nail for unstable per-trochanteric fractures including complications associated with both fixations. METHODS: A retrospective analysis done on pertrochanteric fractures of femur who were treated with Dynamic hip Screw (DHS) and Proximal Femur Nail (PFN). The data was taken from our hospital hip data base for the past two years from January 2017 to January 2019. Data of 174 patients was analysed, divided in to Group A with DHS (n=122) and Group B with PFN (n=52). Follow up included X-ray (anteroposterior and lateral) views for fracture union and collapse, femur neck shortening, implant position and identification of mode of failure or collapse (cut out risk) by using tip-apex distance. The Harris hip score used to evaluate mobility status and other functional outcomes. RESULTS: The mean age in years of patients treated with PFN and DHS were 55.9 and 59.8, ranging from 39-83 years. The mean of Harris hip score at 2 year was 69.28±9.99 in DHS group and 72.12±9.71 in PFN group with the p-value 0.31. The mean of limb shortening was 12mm in DHS and 9 mm in PFN group. In DHS group, four cases had tip-apex distance of 39 mm and reported implant cut out that needs revision of surgery. CONCLUSIONS: Proximal Femur Nail group demonstrated no implant cut out and less mean limb length shortening where as other parameter like functional outcomes, fracture union, rate of infection, hospital stay and postoperative pain are not significantly different in two groups.

Evaluation of Patient Perception and Satisfaction Toward the Use of Telemedicine During Pandemic of Novel Coronavirus in Pakistan.

Background:The trend of telemedicine is exponentially increasing worldwide due to the coronavirus disease (COVID-19) pandemic. However, patient satisfaction is always a concern regarding the use of telemedicine.Introduction:The aim of this study is to evaluate the perception and satisfaction level of patients toward the use of telemedicine during the pandemic of COVID-19 among Pakistani population.Materials and Methods:The survey questionnaires were distributed to 251 patients who received telemedicine consultation in any of three specializations: orthopedic, ophthalmology, and general medicine. The questionnaire contains 15 questions that covered four categories of patient satisfaction: interpersonal communication, caring, care delivery, and proficiency. Descriptive and analytical statistics were obtained by analyzing data using SPSS software version 20.Results:A total of 251 patients responded to the telemedicine questionnaire. Overall, 61.35% patients reported that they did not need any support for using technology during consultation and 96.41% of the patient population reported that telemedicine saved their travel time. It was found that gender, education, and age were significantly associated with the ease in technology with the p-value 0.012, 0.004 and <0.001, respectively, whereas the use of telemedicine again in future is found to be significantly associated with only education and age p-value <0.001. The statistically significant difference was found in three specialized consultation regarding the overall satisfaction, χ2 = 5.83, p-value = 0.05, with a mean rank in orthopedic is 133.6, 134.4 in ophthalmology, and 113.6 in internal medicine.Conclusion:Telemedicine is convenient and satisfactory way to provide health care services during pandemic. Although a considerable number of participants reported good response for telemedicine, there is a need of establishing local telemedicine guidelines, training of consultants and advancement in technology.

Histological and cellular evaluation of anterior cruciate ligament.

BACKGROUND: We hypothesized that the torn anterior cruciate ligament (ACL) demonstrates a great healing response after initial trauma and has competent cells leading to the healing but differs in its response based on the type of tear and duration of injury. This study aimed to evaluate the histological and cellular responses to the injured ACL. METHODS: Fifty-two tissue samples from the ACL were harvested from patients undergoing arthroscopy. Detailed histological and cellular examinations were performed for ligament angiogenesis, fibrocytes, and synovial tissue infiltration. We compared the cellular response to injury in partially and completely ruptured ACLs. The duration of ACL injury and its response to cellular characteristics were also examined. Immunohistochemical studies using cluster of differentiation 34 (CD34) staining was used to evaluate endothelial cells and fibrocytes. RESULTS: We found a significantly higher density of synovial and ligament angiogenesis and fibrocytes at the torn end of ACL (Mann-Whitney, P < 0.050). Numerous fibrocytes were identified in complete ACL tears versus partial tears (Mann-Whitney = 0.020). Increased cellular proliferation was identified at the ruptured end of ACL remnant (Kruskal-Wallis, P < 0.050). The cellular proliferation of ruptured ACL decreased after 12 months. CONCLUSIONS: Based on our findings of the time-dependent decrease in the cellular response at the torn ends of the ACL, we recommend early intervention, preservation of the ACL remnant, and primary ACL repair or augmented reconstruction.

Perioperative Anaesthetic Management for Laparoscopic Gastrectomy in a Patient with Coarctation of Aorta.

Coarctation of the aorta (CoA) is a congenital condition, usually diagnosed and corrected early in life. Long-term survival with untreated coarctation is uncommon and is associated with high mortality rates in the fifth decade. A patient with CoA may present with problems while undergoing cardiac or non-cardiac surgical procedures which could pose considerable challenges in their anaesthetic management. Hence, the choice of anaesthetic technique plays an important role in determining the perioperative course and postoperative outcome in patients with CoA. This report discusses a case of middle-age man, recently diagnosed with CoA while undergoing a preanaesthetic assessment prior to the surgery for gastric adenocarcinoma involving proximal gastro-oesophageal junction. It highlights the successful anaesthetic management of CoA scheduled for laparoscopic-assisted gastrectomy for gastric adenocarcinoma. Perioperative management goals of the patient included general anaesthesia, epidural analgesia to avoid pain-associated adverse effects and efficient control of blood pressure distal to coarctation to limit the risk of intraoperative morbidity. It also demonstrates a major impact on anaesthesiologists who serve the most important role in managing such patients undergoing surgery with 'red flag' features.

Pectoral Nerves I, II and Serratus Plane Blocks in Multimodal Analgesia for Mastectomy: A Randomised Clinical Trial.

OBJECTIVE: To primarily assess pain score in first 24 hours in PECS (PECtoral Serratus) block group undergoing mastectomy; secondary objective was to observe opioid and antiemetic consumption in the postoperative period. STUDY DESIGN: Observer-blinded randomised control trial. PLACE AND DURATION OF STUDY: Department of Anesthesiology, Shaukat Khanum Memorial Cancer Hospital Lahore (SKMCH), from February to December 2017. METHODOLOGY: One hundred and twenty patients of more than 18 years, ASA I and II, planned for unilateral elective modified radical mastectomy under general anesthesia, were scheduled randomly to receive either general anesthesia plus PECS block (n = 60) or general anesthesia alone (n = 60). Pain scores at fixed intervals were measured using Numeric Pain Rating Score (NPRS) after the surgery. RESULTS: Pain score in the PECS block group was significantly lower than the control group in postoperative period. Less dose of morphine was required in the PECS block group postoperatively for pain control. Postoperative nausea and vomiting (PONV) incidence was lower in the intervention group (PECS block) as compared with the control group. CONCLUSION: PECS block has a better analgesic efficacy in patients undergoing mastectomy.

Painless squeaking following cervical disc replacement: A case report.

BACKGROUND: We present a case of painless squeaking following cervical disc replacement which to our knowledge has not previously been reported in the literature. METHODS: A 45 year old gentleman presented with severe right sided C6 radiculopathy. He complained of more than 6 weeks of severe dysaesthesia in the right arm with pain radiating into the hand, thumb, index, middle and ring fingers. MRI confirmed severe impingement of C6 and C7 nerve roots. After trying a period of conservative treatment he underwent anterior cervical decompression with total cervical disc replacement of C5-6 and C6-7. RESULTS: Being a keen athlete he started running at 6 months post operatively. At his 12 month outpatient he presented us with an audio file containing squeaking from his neck. This was recorded immediately following a 9.5 mile hard surface run. The squeak got progressively less in intensity over 12 hours and disappeared after 24 hours. All instances of squeaking occurred after exercise where impact (running) or vibration (cycling) took place. This was first noticed 6 months post operatively when he restarted exercising. All episodes were completely painless. At his 18 month outpatient review the squeaking had reduced in frequency and intensity. At his 24 month review it had abated completely. CONCLUSION: The aetiology of this painless squeaking has been elusive and is likely to be multifactorial. However we hypothesise that the audible squeak associated with the prestige LP disc maybe related to specific design characteristics and needs further evaluation.

Neurokinin 3 receptor and phosphocholine transferase: missing factors for pathogenesis of C-reactive protein in preeclampsia.

C-reactive protein (CRP), an innate immune mediator, is elevated in the circulation before symptoms in patients with preeclampsia, a severe hypertensive pregnancy disorder with high mortality and morbidity. However, the specific sources underlying increased CRP and the role of elevated CRP in preeclampsia are undefined. Here, we report that circulating CRP levels are significantly increased in a large cohort of normotensive pregnant individuals when compared with nulligravid women and is further increased in patients with preeclampsia. These findings led us to discover further that placental syncytiotrophoblasts are previously unrecognized cellular sources of CRP and underlie elevated CRP in normotensive pregnant women and the additional increase in patients with preeclampsia. Next, we demonstrated that injection of CRP induces preeclampsia features, including hypertension (157 mm Hg CRP treated versus 119 mm Hg control), proteinuria (35.0 mg/µg CRP treated versus 14.1 mg/µg control), kidney, and placental damage and increased levels of sFlt-1 in pregnant mice but not in nonpregnant mice. Our study implicates that phosphocholine transferase, a placental-specific enzyme post-translationally modifying neurokinin B, is essential for the pathogenic role of CRP in preeclampsia through activation of the neurokinin 3 receptor. Overall, our studies have provided significant new insight on the pathogenic role of CRP in preeclampsia and highlighted innovative therapeutic strategies.

Angiotensin receptor agonistic autoantibody-mediated soluble fms-like tyrosine kinase-1 induction contributes to impaired adrenal vasculature and decreased aldosterone production in preeclampsia.

Preeclampsia (PE) is a life-threatening hypertensive disorder during pregnancy associated with decreased circulating aldosterone levels. However, the molecular mechanisms underlying aldosterone reduction in PE remain unidentified. Here we demonstrate that reduced circulating aldosterone levels in preeclamptic women are associated with the presence of angiotensin II type 1 receptor agonistic autoantibody and elevated soluble Fms-like tyrosine kinase-1, 2 prominent pathogenic factors in PE. Using an adoptive transfer animal model of PE, we provide in vivo evidence that the injection of IgG from women with PE, but not IgG from normotensive individuals, resulted in hypertension, proteinuria, and a reduction in aldosterone production from 1377 ± 272 pg/mL to 544 ± 92 pg/mL (P<0.05) in pregnant mice. These features were prevented by coinjection with an epitope peptide that blocks antibody-mediated angiotensin type 1 receptor activation. In contrast, injection of IgG from preeclamptic women into nonpregnant mice induced aldosterone levels from 213 ± 24 pg/mL to 615 ± 48 pg/mL (P<0.05). These results indicate that maternal circulating autoantibody in preeclamptic women is a detrimental factor causing decreased aldosterone production via angiotensin type 1 receptor activation in a pregnancy-dependent manner. Next, we found that circulating soluble Fms-like tyrosine kinase-1 was only induced in autoantibody-injected pregnant mice but not nonpregnant mice. As such, we further observed vascular impairment in adrenal glands of pregnant mice. Finally, we demonstrated that infusion of vascular endothelial growth factor(121) attenuated autoantibody-induced adrenal gland vascular impairment resulting in a recovery in circulating aldosterone (from 544 ± 92 to 1110 ± 269 pg/mL; P<0.05). Overall, we revealed that angiotensin II type 1 receptor agonistic autoantibody-induced soluble Fms-like tyrosine kinase-1 elevation is a novel pathogenic mechanism underlying decreased aldosterone production in PE.

Pseudohypoparathyroidism as a rare cause of bilateral slipped capital femoral epiphysis.

Slipped capital femoral epiphysis (SCFE) is a disorder of adolescent age. Presentation of SCFE earlier than the expected age range should prompt the clinician to consider the presence of an underlying endocrinopathy. Early recognition and aggressive management of the predisposing endocrine disorder is crucial to prevent treatment failure and associated morbidity. We report the clinical presentation and treatment of an 8-year-old girl with bilateral slipped capital femoral epiphysis. The unusual age, persistent hypocalcemia, and associated distal femoral physeal deformities prompted further evaluations, which led to the diagnosis of pseudohypoparathyroidism type 1b. PHP type 1b is an extremely rare cause of SCFE and only a few cases have been reported. A delay in diagnosis in such case is not uncommon.

Recombinant vascular endothelial growth factor 121 attenuates autoantibody-induced features of pre-eclampsia in pregnant mice.

BACKGROUND: Pre-eclampsia (PE) is a serious hypertensive disorder of pregnancy characterized by excessive production of a soluble form of the vascular endothelial growth factor (VEGF) receptor-1, termed soluble fms-like tyrosine kinase-1 (sFlt-1). This placental-derived factor is believed to be a key contributor to the clinical features of PE. Women with PE are also characterized by the presence of autoantibodies, termed angiotensin type 1 receptor activating autoantibody (AT(1)-AA), that activate the major angiotensin receptor, AT(1). These autoantibodies cause clinical features of PE and elevated sFlt-1 when injected into pregnant mice. The research reported here used this autoantibody-injection model of PE to assess the therapeutic potential of recombinant VEGF(121), a relatively stable form of the natural ligand. METHODS: Immunoglobulin G (IgG) from women with PE was injected into pregnant mice with or without continuous infusion of recombinant VEGF(121). Injected mice were monitored for symptoms of PE. RESULTS: As a result of infusion of recombinant VEGF(121) autoantibody-induced hypertension (systolic blood pressure) was reduced from 159 ± 5 to 124 ± 5 mm Hg, proteinuria from 111 ± 16 to 40 ± 5 mg protein/mg creatinine and blood urea nitrogen levels from 31 ± 1 mg/dl to 18 ± 2 mg/dl, P < 0.05. Histological analysis revealed that autoantibody-induced glomerular damage including the narrowing of Bowman's space and occlusion of capillary loop spaces was largely prevented by VEGF(121) infusion. Finally, impaired placental angiogenesis resulting from AT(1)-AA injection was significantly improved by VEGF(121) infusion. CONCLUSIONS: The infusion of recombinant VEGF(121) significantly attenuated autoantibody-induced features of PE.

Short-term in vitro and in vivo genotoxicity testing systems for some water bodies of Northern India.

The genotoxicity of certain water bodies was evaluated employing the DNA repair defective mutants of Escherichia coli, induction of prophage lamda in the lysogen and the plasmid nicking assay. All the test DNA repair defective mutants invariably exhibited more sensitivity than their isogenic wild-type strains but distinctive patterns against the three water samples viz. industrial waste water and the groundwater samples obtained from industrial estate of Aligarh as well as river water of Yamuna at Agra. A significant level of phage induction was also recorded in the test system exhibiting maximum induction in case of industrial waste water followed by that in river and groundwater samples, respectively. The single- and double-strand breaks were also observed in the plasmid DNA treated with industrial waste water and the river water samples. These findings are suggestive of the DNA damage induced by the test samples with the probable role of SOS repair in E. coli.

Validation of plant based bioassays for the toxicity testing of Indian waters.

Plant-based bioassays have recently gained remarkable popularity among the toxicological/eco-toxicological assessment procedures. The reasons for their wide use are comparative simplicity, sensitivity, and cost-effectiveness as well as a good correlation with other toxicity tests. The present study describes the use of two plant bioassays, Allium cepa test and seed germination test in the evaluation of the toxicity/genotoxicity of industrial waste water and river water and standardization with the commonly occurring pollutants in Indian waters namely heavy metals and phenolics. Both tests were standardized to suit the Indian conditions, and the local varieties were used. Both bioassays responded significantly with the test range of heavy metals and phenolics. The toxicity of heavy metals was in the order of Cu > Ni > Cd in both the tests whereas 2,4-dinitrophenol was the most toxic among the phenolic compounds. Cabbage, millet, and cucumber, respectively, were found to be the most sensitive in the seed germination test for the test heavy metals and phenols. Significant amounts of chromosomal abnormalities including bridges, stickiness, and fragmentations were recorded with both the industrial waste water and the XAD concentrated river water samples by A. cepa test.

Angiotensin receptor agonistic autoantibody is highly prevalent in preeclampsia: correlation with disease severity.

Preeclampsia (PE), a syndrome affecting 5% of pregnancies, characterized by hypertension and proteinuria, is a leading cause of maternal and fetal morbidity and mortality. The condition is often accompanied by the presence of a circulating maternal autoantibody, the angiotensin II type I receptor agonistic autoantibody (AT(1)-AA). However, the prevalence of AT(1)-AA in PE remains unknown, and the correlation of AT(1)-AA titers with the severity of the disease remains undetermined. We used a sensitive and high-throughput luciferase bioassay to detect AT(1)-AA levels in the serum of 30 normal, 37 preeclamptic (10 mild and 27 severe), and 23 gestational hypertensive individuals. Here we report that AT(1)-AA is highly prevalent in PE ( approximately 95%). Next, by comparing the levels of AT(1)-AA among women with mild and severe PE, we found that the titer of AT(1)-AA is proportional to the severity of the disease. Intriguingly, among severe preeclamptic patients, we discovered that the titer of AT(1)-AA is significantly correlated with the clinical features of PE: systolic blood pressure (r=0.56), proteinuria (r=0.70), and soluble fms-like tyrosine kinase-1 level (r=0.71), respectively. Notably, only AT(1)-AA, and not soluble fms-like tyrosine kinase-1, levels are elevated in gestational hypertensive patients. These data serve as compelling clinical evidence that AT(1)-AA is highly prevalent in PE, and its titer is strongly correlated to the severity of the disease.

Protective role of angiotensin II subtype 2 receptor in blood pressure increase in obese Zucker rats.

Earlier, we reported that there was an increase in angiotensin II type 2 (AT(2)) receptor expression in the renal proximal tubule, and selective activation of the AT(2) receptor by AT(2) agonist inhibits Na,K-ATPase activity in the proximal tubules and increases urinary Na excretion in obese Zucker rats. We hypothesized that the AT(2) receptor has a protective role against blood pressure increase in obese Zucker rats. To test this hypothesis, we treated obese Zucker rats with the AT(2) receptor antagonist PD123319 (PD; 30 microg/kg per minute) using osmotic pumps. Age-matched lean rats and vehicle-treated obese Zucker rats served as controls. On day 15 of the treatment with PD, arterial blood pressure was measured by cannulation of the left carotid artery under anesthesia. Control obese rats exhibited higher mean arterial pressure (122.0+/-3.4 mm Hg) compared with lean control rats (97.0+/-4.8 mm Hg). The PD treatment of obese rats raised mean arterial pressure further by 13 mm Hg. The plasma renin activity was significantly increased in the PD-treated obese compared with control-obese or lean rats. Western blot analysis revealed that the PD treatment in obese rats caused an approximately 3-fold increase in the renin expression in the kidney cortex but had no effect on the expression of the cortical angiotensin II type 1 and AT(2) receptors. The present study suggests that the renal AT(2) receptors provide a protective role against blood pressure increase in obese Zucker rats, and this protective effect, in part, could be because of the ability of the AT(2) receptors to keep the kidney renin expression low in obese rats.

Impaired angiotensin II AT(1) receptor function and enhanced Na, K-ATPase affinity for sodium in proximal tubule of streptozotocin-treated diabetic rats.

We determined angiotensin II (Ang II) AT(1) receptor function in terms of Na-K-ATPAse (NKA) stimulation in the proximal tubule (PTs) of streptozotocin-induced diabetic rats. Ang II (10 pM) stimulated NKA activity in PTs of control rats but not diabetic rats. The AT(1) receptor expression was similar, but the expression of G-proteins (G(i)alpha2 and G(i)alpha3) in the PTs was decreased in diabetic compared with control rats. Kinetic studies revealed an increase in NKA affinity, low K(0.5,) for Na, with no changes in V(max) of the enzyme in diabetic compared with control rats. Basal Ser-phosphorylation of NKA alpha1-subunit was lower in diabetic compared with control rats. This data suggest that the higher basal NKA affinity for Na, possibly due to lower Ser-phosphorylaion of alpha1-subunit and not the AT(1) receptor function, in the PTs may be responsible for increased renal Na reabsorption associated with early stage of streptozotocin-induced diabetes.

Enhanced AT1 receptor-mediated vasocontractile response to ANG II in endothelium-denuded aorta of obese Zucker rats.

In the present study, we tested the hypothesis that ANG II causes a greater vasoconstriction in obese Zucker rats, a model of type 2 diabetes, with mild hypertension. Measurement of isometric tension in isolated aortic rings with intact endothelium revealed a modest but not significantly greater ANG II-induced contraction in obese than lean rats. Removal of endothelium or inhibition of nitric oxide (NO) synthase by N(G)-nitro-L-arginine methyl ester (L-NAME) enhanced 1) ANG II-induced contraction in both lean and obese rats, being significantly greater in obese rats (E(max) g/g tissue, denuded: lean 572 +/- 40 vs. obese 664 +/- 16; L-NAME: lean 535 +/- 14 vs. obese 818 +/- 23) and 2) ANG II sensitivity in obese compared with lean rats, as revealed by the pD(2) values. Endothelin-1 and KCl elicited similar contractions in the aortic rings of lean and obese rats. ACh, a NO-dependent relaxing hormone, produced greater relaxation in the aortic rings of obese than lean rats, whereas sodium nitroprusside, an NO donor, elicited similar relaxations in both rat strains. The expression of the ANG type 1 (AT(1)) receptor protein and mRNA in the endothelium-intact aorta was significantly greater in obese than lean rats, whereas the endothelium-denuded rings expressed modest but not significantly greater levels of AT(1) receptors in obese than lean rats. The endothelial NO synthase protein and mRNA expression levels were higher in the aorta of obese than lean animals. We conclude that, although ANG II produces greater vasoconstriction in obese rat aortic rings, enhanced endothelial AT(1) receptor-mediated NO production appears to counteract the increased ANG II-induced vasoconstriction, suggesting that arterial AT(1) receptor may not be a contributing factor to hypertension in this model of obesity.

Renal angiotensin II AT2 receptors promote natriuresis in streptozotocin-induced diabetic rats.

Angiotensin II AT2 receptors have been implicated to play a role in the regulation of renal/cardiovascular functions under pathological conditions. The present study is designed to investigate the function of the AT2 receptors on renal sodium excretion and AT(2) receptor expression in the cortical membranes of streptozotocin (STZ)-induced diabetic rats. The STZ treatment led to a significant weight loss, hyperglycemia, and decrease in plasma insulin levels compared with control rats. STZ-induced diabetic rats had significantly elevated basal urine flow, urinary sodium excretion rate (U(Na)V), urinary fractional sodium excretion, and urinary cGMP compared with control rats. Infusion of PD-123319, an AT2 receptor antagonist, caused a significant decrease in U(Na)V (mumol/min) in STZ-induced diabetic rats (1 +/- 0.09 vs. 0.45 +/- 0.1) but not in control rats (0.35 +/- 0.05 vs. 0.4 +/- 0.07). The decrease in U(Na)V was associated with a significant decrease in urinary cGMP levels (pmol/min) in STZ-induced diabetic rats (21 +/- 2 vs. 10 +/- 0.8) but not in control rats (11.75 +/- 3 vs. 12.6 +/- 2). The infusion of PD-123319 did not alter glomerular filtration rate (STZ: 0.3 +/- 0.02 vs. 0.25 +/- 0.03; control: 1.4 +/- 0.05 vs. 1.5 +/- 0.09 ml/min) or mean arterial pressure (STZ: 82 +/- 3 vs. 79 +/- 3.5; control: 90 +/- 4 vs. 89 +/- 4 mmHg), suggesting a tubular effect of the drug. Western blot analysis using an AT2 receptor antibody revealed a significantly enhanced expression of the AT2 receptor protein ( approximately 45 kDa) in brush-border ( approximately 50-fold) and basolateral membranes ( approximately 80-fold) of STZ-induced diabetic compared with control rats. In conclusion, our data suggest that the tubular AT2 receptors in diabetic rats are profoundly enhanced and possibly via a cGMP pathway promote sodium excretion in this model of diabetes.