The improving effect and mechanisms of Anshen Dingzhi Prescription on Alzheimer's disease-like behavior induced by D-galactose combined with AβO in mice / 药学学报

The purpose of this study was to explore the improving effect of Anshen Dingzhi Prescription (ADP) on Alzheimer's disease (AD)-like behavior in mice and its mechanisms. The main chemical components of ADP were identified by ultra performance liquid chromatography-time-of-flight mass spectrometry (UPLC-Q-TOF-MS). The AD-like mouse model was induced by D-galactose (D-gal) combined with Aβ1-42 oligomer (AβO). The effect of ADP on AD-like behavior in mice was assessed using various behavioral experiments; pathomorphological changes in mouse hippocampal tissue were observed by Nissl staining and transmission electron microscopy; ELISA was used in the assessment of oxidative stress factors and inflammation-related factor levels; Western blot was performed to detect the expression of Aβ, Tau and glial fibrillary acidic protein (GFAP) proteins. The active components of ADP were screened according to TCMSP and HERB database, and the action targets of active components were predicted by Swiss Target Prediction platform. In addition, the targets of AD were predicted through DisGeNET database. Further, GO and KEGG enrichment analysis of common targets was carried out by Metascape database. Combined with the results of GO and KEGG analysis, in vivo experiments were carried out to explore the potential mechanism of ADP improving AD-like behavior in mice from the PI3K/Akt, calcium signal pathway and synaptic function. Finally, the core components of ADP were molecularly docked to the validated targets using Autodock Vina. Animal experiments were approved by the Animal Ethics Committee of Anhui University of Chinese Medicine (approval number: AHUCM-mouse-2021080). The results showed that the five chemical components, including ginsenoside Rg1, ginsenoside Rb1, tenuifolin, poricoic acid B and α-asarone were found in the ADP. ADP significantly improved the anxiety-like behavior and memory impairment, protected hippocampal neurons, decreased the levels of oxidative stress and inflammation, and inhibited the expression of Aβ and p-Tau induced by D-galactose combined with AβO in mice. The results of network pharmacology suggested that PI3K/Akt, calcium signal pathway and cell components related to postsynaptic membrane might be the key factors for ADP to improve AD. Animal experiments revealed that ADP up-regulated N-methyl-D-aspartate receptor 2A (GluN2A), postsynaptic density protein 95 (PSD95), calpain-1, phosphorylated protein kinase B (p-Akt), phosphorylated cAMP response element binding protein (p-CREB), brain-derived neurotrophic factor (BDNF) expression and inhibited p-GluN2B and calpain-2 expression in the hippocampus of AD-like mice. The molecular docking results demonstrated that the core components of ADP, such as panaxacol, dehydroeburicoic acid, deoxyharringtonine, etc. had a high binding ability with the validated targets GRIN2A, GRIN2B, PSD95, etc. In summary, our results indicate ADP improves AD-like pathological and behavioral changes induced by D-galactose combined with AβO in mice, and the mechanism might be related to the NMDAR/calpain axis and Akt/CREB/BDNF pathway.

NOX4/Src regulates ANP secretion through activating ERK1/2 and Akt/GATA4 signaling in beating rat hypoxic atria

Nicotinamide adenine dinucleotide phosphate oxidases (NOXs) are the major enzymatic source of reactive oxygen species (ROS). NOX2 and NOX4 are expressed in the heart but its role in hypoxia-induced atrial natriuretic peptide (ANP) secretion is unclear. This study investigated the effect of NOX on ANP secretion induced by hypoxia in isolated beating rat atria. The results showed that hypoxia significantly upregulated NOX4 but not NOX2 expression, which was completely abolished by endothelin-1 (ET-1) type A and B receptor antagonists BQ123 (0.3 µM) and BQ788 (0.3 µM). ET-1-upregulated NOX4 expression was also blocked by antagonists of secreted phospholipase A2 (sPLA2; varespladib, 5.0 µM) and cytosolic PLA2 (cPLA2; CAY10650, 120.0 nM), and ET-1-induced cPLA2 expression was inhibited by varespladib under normoxia. Moreover, hypoxia-increased ANP secretion was evidently attenuated by the NOX4 antagonist GLX351322 (35.0 µM) and inhibitor of ROS N-Acetyl-D-cysteine (NAC, 15.0 mM), and hypoxia-increased production of ROS was blocked by GLX351322. In addition, hypoxia markedly upregulated Src expression, which was blocked by ET receptors, NOX4, and ROS antagonists. ET-1-increased Src expression was also inhibited by NAC under normoxia. Furthermore, hypoxiaactivated extracellular signal-regulated kinase 1/2 (ERK1/2) and protein kinase B (Akt) were completely abolished by Src inhibitor 1 (1.0 µM), and hypoxia-increased GATA4 was inhibited by the ERK1/2 and Akt antagonists PD98059 (10.0 µM) and LY294002 (10.0 µM), respectively. However, hypoxia-induced ANP secretion was substantially inhibited by Src inhibitor. These results indicate that NOX4/Src modulated by ET-1 regulates ANP secretion by activating ERK1/2 and Akt/GATA4 signaling in isolated beating rat hypoxic atria.

NOX4/Src regulates ANP secretion through activating ERK1/2 and Akt/GATA4 signaling in beating rat hypoxic atria

Nicotinamide adenine dinucleotide phosphate oxidases (NOXs) are the major enzymatic source of reactive oxygen species (ROS). NOX2 and NOX4 are expressed in the heart but its role in hypoxia-induced atrial natriuretic peptide (ANP) secretion is unclear. This study investigated the effect of NOX on ANP secretion induced by hypoxia in isolated beating rat atria. The results showed that hypoxia significantly upregulated NOX4 but not NOX2 expression, which was completely abolished by endothelin-1 (ET-1) type A and B receptor antagonists BQ123 (0.3 µM) and BQ788 (0.3 µM). ET-1-upregulated NOX4 expression was also blocked by antagonists of secreted phospholipase A2 (sPLA2; varespladib, 5.0 µM) and cytosolic PLA2 (cPLA2; CAY10650, 120.0 nM), and ET-1-induced cPLA2 expression was inhibited by varespladib under normoxia. Moreover, hypoxia-increased ANP secretion was evidently attenuated by the NOX4 antagonist GLX351322 (35.0 µM) and inhibitor of ROS N-Acetyl-D-cysteine (NAC, 15.0 mM), and hypoxia-increased production of ROS was blocked by GLX351322. In addition, hypoxia markedly upregulated Src expression, which was blocked by ET receptors, NOX4, and ROS antagonists. ET-1-increased Src expression was also inhibited by NAC under normoxia. Furthermore, hypoxiaactivated extracellular signal-regulated kinase 1/2 (ERK1/2) and protein kinase B (Akt) were completely abolished by Src inhibitor 1 (1.0 µM), and hypoxia-increased GATA4 was inhibited by the ERK1/2 and Akt antagonists PD98059 (10.0 µM) and LY294002 (10.0 µM), respectively. However, hypoxia-induced ANP secretion was substantially inhibited by Src inhibitor. These results indicate that NOX4/Src modulated by ET-1 regulates ANP secretion by activating ERK1/2 and Akt/GATA4 signaling in isolated beating rat hypoxic atria.

Lamotrigine induced hypersensitivity syndrome in children: a case report / 北京大学学报(医学版)

Drug induced hypersensitivity syndrome (DIHS) is often manifested as severe systemic drug trans-reactions characterized by acute and extensive skin lesions (mostly measles-like rash), fever, enlargement of lymph nodes, multiple organ involvement (hepatitis, nephritis, and pneumonia), eosinophilia and mononucleosis,within 2-6 weeks of the application of sensitizing drugs. In the early stage of the lesion, macular papules or erythema multiforme were common, and in severe cases, exfoliative dermatitis, Stevens-Johnson syndrome and toxic epidermal necrolysis were also common. Most of them developed after taking allergic drugs for 2-6 weeks (average: 3 weeks). Symptoms persisted after discontinuation of allergic drugs. It takes more than one month to alleviate, which may endanger life in severe cases. Documents report that the most common drugs causing DIHS are phenytoin sodium, carbamazepine and phenobarbital aromatic drugs. However, it was reported that phenobarbital sodium was the most common anticonvulsant among allergenic drugs in children, followed by antipyretics, analgesics and antibiotics, which may be related to the spectrum of childhood diseases and the particularity of the drug. Lamotrigine has been reported to cause DIHS in adults in China, but less in children. In order to improve the understanding of clinical diagnosis and treatment of DIHS in children, reduce misdiagnosis, missed diagnosis, and untimely treatment, and prevent the aggravation of the disease, we studied the case of a 4-year-old 7-month-old girl who presented with systemic erythematous papules, fever, hepatosplenomegaly, marked increase of white blood cells, marked decrease of anemia and platelets, abnormal liver function and coagulation routine after taking lamotrigine for one month due to epilepsy seizures. Now, according to the DIHS diagnostic criteria established by Registration of Severe Cutaneous Adverse Reactions Drug Review Group in 2007, plasma exchange was immediately given to replace the toxic metabolites in hemorrhagic plasma, and methylprednisolone was given intravenously for three days. At the same time, after symptomatic supportive treatments, such as loratadine and albumin, the condition gradually improved without recurrence. Through a case report of Drug reaction with eosinophilia and systemic symptoms in a child caused by lamotrigine, we can strengthen our understanding and improve the level of diagnosis and treatment of drug hypersensitivity syndrome in children. Lamotrigine can cause DIHS in children, which is very dangerous. Early diagnosis and early withdrawal of allergenic drugs, plasma exchange and glucocorticoid therapy are the key to treatment.

Peroxisome proliferator-activated receptor γ is essential for secretion of ANP induced by prostaglandin D₂ in the beating rat atrium

Prostaglandin D₂ (PGD₂) may act against myocardial ischemia-reperfusion (I/R) injury and play an anti-inflammatory role in the heart. Although the effect of PGD₂ in regulation of ANP secretion of the atrium was reported, the mechanisms involved are not clearly identified. The aim of the present study was to investigate whether PGD₂ can regulate ANP secretion in the isolated perfused beating rat atrium, and its underlying mechanisms. PGD₂ (0.1 to 10 µM) significantly increased atrial ANP secretion concomitantly with positive inotropy in a dose-dependent manner. Effects of PGD₂ on atrial ANP secretion and mechanical dynamics were abolished by AH-6809 (1.0 µM) and AL-8810 (1.0 µM), PGD₂ and prostaglandin F2α (PGF2α) receptor antagonists, respectively. Moreover, PGD₂ clearly upregulated atrial peroxisome proliferator-activated receptor gamma (PPARγ) and the PGD₂ metabolite 15-deoxy-Δ12,14-PGJ₂ (15d-PGJ₂, 0.1 µM) dramatically increased atrial ANP secretion. Increased ANP secretions induced by PGD₂ and 15d-PGJ₂ were completely blocked by the PPARγ antagonist GW9662 (0.1 µM). PD98059 (10.0 µM) and LY294002 (1.0 µM), antagonists of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) and phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt) signaling, respectively, significantly attenuated the increase of atrial ANP secretion by PGD₂. These results indicated that PGD₂ stimulated atrial ANP secretion and promoted positive inotropy by activating PPARγ in beating rat atria. MAPK/ERK and PI3K/Akt signaling pathways were each partially involved in regulating PGD₂-induced atrial ANP secretion.

cAMP induction by ouabain promotes endothelin-1 secretion via MAPK/ERK signaling in beating rabbit atria

Adenosine 3',5'-cyclic monophosphate (cAMP) participates in the regulation of numerous cellular functions, including the Na(+)-K(+)-ATPase (sodium pump). Ouabain, used in the treatment of several heart diseases, is known to increase cAMP levels but its effects on the atrium are not understood. The aim of the present study was to examine the effect of ouabain on the regulation of atrial cAMP production and its roles in atrial endothelin-1 (ET-1) secretion in isolated perfused beating rabbit atria. Our results showed that ouabain (3.0 micromol/L) significantly increased atrial dynamics and cAMP levels during recovery period. The ouabain-increased atrial dynamics was blocked by KB-R7943 (3.0 micromol/L), an inhibitor for reverse mode of Na(+)-Ca(2+) exchangers (NCX), but did not by L-type Ca2+ channel blocker nifedipine (1.0 micromol/L) or protein kinase A (PKA) selective inhibitor H-89 (3.0 micromol/L). Ouabain also enhanced atrial intracellular cAMP production in response to forskolin and theophyline (100.0 micromol/L), an inhibitor of phosphodiesterase, potentiated the ouabain-induced increase in cAMP. Ouabain and 8-Bromo-cAMP (0.5 micromol/L) markedly increased atrial ET-1 secretion, which was blocked by H-89 and by PD98059 (30 micromol/L), an inhibitor of extracellular-signal-regulated kinase (ERK) without changing ouabain-induced atrial dynamics. Our results demonstrated that ouabain increases atrial cAMP levels and promotes atrial ET-1 secretion via the mitogen-activated protein kinase (MAPK)/ERK signaling pathway. These findings may explain the development of cardiac hypertrophy in response to digitalis-like compounds.

Effect of chaperone-mediated autophagy in MPP(+) -induced SH-SY5Y cells and interventional effect of puerarin / 中国中药杂志

<p><b>OBJECTIVE</b>To study the protective effect of puerarin on MPP(+) -induced SH-SY5Y cells by chaperone-mediated autophagy (CMA).</p><p><b>METHOD</b>The Parkinson's disease cell model was established by injuring SH-SY5Y cells with 1 mmol x L(-1) MPP+. The CCK-8 staining was adopted to detect the effect the puerarin of different concentrations on the survival rate of MPP(+)-induced SH-SYSY cells. The autophagosome formation was observed under transmission electron microscope. The AO staining showed the changes in the lysosome activity. RT-PCR was used to detect the changes in Lamp2a and Hsc70 mRNA expressions. The western blotting was adopted to test the expressions of Lamp2a, Hsc70 and alpha-synuclein protein in cells.</p><p><b>RESULT</b>Within the concentration range of 12. 5-50.0 micromol x L(-1), the pretreatment with puerain for 30 minutes could protect the injury of MPP+ in SH-SY5Y cells, and showed a certain dose-effect relationship. The AO staining and electron microscope showed the effect of puerain within the concentration range of 12.5-50.0 micromol x L(-1) on 1 mmol x L(-1) MPP(+)-induced SH-SY5Y cells; autophagosomes emerged in cells, and increased along with the rise in the puerarin dose. The results of the flow cytometry revealed that 50.0 micromol x L(-1) of puerarin could protect against the increase of the ROS level in 1 mmol x L(-1) MPP(+) -induced SH-SY5Y cells and prevent the oxidative injury. The results of RT-PCR and western blotting indicated that puerain within the concentration range of 12.5-50.0 micromol x L(-1) alleviated the MPP(+)-induced SH-SY5Y cell injury, and inhibited the accumulation of alpha-synuclein proteins in MPP(+) -induced SH-SY5Y cells by up-regulating Hsc70, Lamp2a mRNA and protein level.</p><p><b>CONCLUSION</b>Puerarin could protect against the MPP(+) -induced cell injury, whose protective mechanism may be related to the chaperone-mediated autophagy pathway of interventional molecules.</p>

Quantitative determination of metoprolol by liquid chromatography mass spectrometry in rat plasma / 军事医学科学院院刊

Objective:To establish a highly sensitive, rapid and selective liquid chromatography mass spectrometry (LC-MS) method for the determination of metoprolol in rat plasma.Methods:A simplified liquid-liquid extraction with acetidin was employed for the sample preparation. The separation was carried out on a Thermo ODS-C_(18)(5 μm,100 mm×2.1 mm).The mobile phase consisted of acetonitrile-methanol-water(20∶20∶60). Propranolol was used as the internal standard. The detection was performed on a liquid chromatography mass spectrometry by selected ion monitoring(SIM) scan mode electrospray ionization(ESI).Results and Conclusion:The range of calibration curve was 0.1-50 ng/ml and the limit of quantification was 0.1 ng/ml. The intra- and inter-day precision RSD was less than 15%.This method is sensitive, simple,rapid and suitable for the pharmacokinetic study of metoprolol.

Effect of hyperkalemic solution on atrial natriuretic peptide secretion / 中国综合临床

Objective To define the effect and mechanism of hyperkalemic solution on atrial natriuretic peptide (ANP) secretion in rabbits. Methods Eighteen rabbits were selected and the chest was opened under anes-thetization to remove the heart. The left atrium was isolated and fixed in the atrial perfusion system with proper electric stimulation for beating. The following experiments were carried out on beating rabbit atria: ①The atrium was perfused for 60 min to stabilize parameters of ANP secretion and atrial dynamics. The control period (12 min as an experimental cycle) was followed by an infusion of hyperkalemic solution (K+ concentration of hyperkalemic solution was 5.64 mmol/L and the osmolarity of hyperkalemic solution was unchanged) for three cycles, then normal K+ cancentration was recovered for two cycles;②The control period was followed by an infusion of L type Ca2+ channel blocker nifedipine (1.0 μmol/L) for three cycles;③L type Ca2+ channel inhibitor nifedipine (1.0 μmol/L) was infused for 36 rain prior (three cycles) to infusion of hyperkalemic solution. Atrial stroke volume was determined and the ANP secretion was measured by radioimmtmoaasay. Results (1)Hyperkalemic solution increased atrial ANP secretion (P<0.01) and reduced the atrial stroke volume,hut the difference was not statistically significant as compared with that of the control cycle(P>0.05). The recovery trend was to the normal level of ANP secretion and atrial stroke volume was to become normal gradually when solution level recovered to normal ,which was not significantly different from that of the control cycle (P>0.05) ;②Nifedipine (1.0 μmol/L) also increased the atrial ANP secretion (P<0.01 or P <0.05) while decreasing atrial stroke volume (P<0.01 or P < 0.05 ) ; ③Nifodipine (1.0μmol/L) completely blocked the effect of hyperkalemic solution so to increase the ANP secretion (P <0.01 ). Conclusion Hyperkalemic solution significantly increases atrial ANP secretion via extracellular high K+ competitive inhibition of extracellular Ca2+ inflow in beating rabbit atria.

Pharmacokinetics of 6beta-naltrexol after single and multiple intramuscular injections in Beagle dogs / 药学学报

The pharmacokinetics of 6beta-naltrexol (6beta-NOL) following single intramuscular administration and multiple intramuscular injection once per day for seven days was studied in 4 Beagle dogs. Plasma concentration of 6beta-NOL in dogs was analyzed by a combination of high performance liquid chromatography (HPLC) and electrochemical detection with naloxone (NLX) as internal standard. After single intramuscular injection of 0.2 mg x kg(-1) 6beta-NOL, the plasma concentration-time curve of the drug was found to fit to a two compartment model with first-order absorption. The main parameters of single dosing were as follows: t1/2alpha was (0.26 +/- 0.23) h, t1/2beta was (4.77 +/- 1.65) h, C(max) was (81.65 +/- 5.61) ng x mL(-1), t(peak) was (0.27 +/- 0.07) h, CL(s) was (1.20 +/- 0.06) L x kg(-1) x h(-1), V/F(c) was (1.94 +/- 0.15) L x kg(-1), and AUC(0-t) was (166.82 +/- 7.68) ng x h x mL(-1), separately. After multiple intramuscular injection of 0.2 mg x kg(-1) 6beta-NOL once per day for seven days, the plasma concentration-time curve of the drug fitted to a two compartment model with first-order absorption too. The main parameters of the last dosing were as follows: t1/2alpha was (0.19 +/- 0.18) h, t1/2beta was (5.79 +/- 1.50) h, C(max) was (79.82 +/- 10.5) ng x mL(-1), t(peak) was (0.18 +/- 0.08) h, CL(s) was (1.12 +/- 0.07) L x kg(-1) x h(-1), V/F(c) was (2.10 +/- 0.27) L x kg(-1), and AUC(0-t) was (173.23 +/- 9.49) ng x h x mL(-1), separately. The difference of the parameters between the first and the last dosing was not significant, showing that the plasma kinetics of 6beta-naltrexol was not changed after multiple administrations. In the course of multiple administration, the peak and valley concentration of plasma 6beta-naltrexol were (79.03 +/- 10.3) and (1.50 +/- 0.93) ng x mL(-1), respectively. No clear adverse events were noted during this study. These results showed that plasma 6beta-naltrexol fits to a two compartment model with first-order absorption in dog after intramuscular administration and their pharmacokinetic parameters were reported. There was no remarkable change on plasma pharmacokinetics of 6beta-naltrexol after multiple intramuscular administrations.

Evaluation of percutaneous vertebroplasty of 190 cases / 中国骨伤

<p><b>OBJECTIVE</b>To evaluate the therapeutic effect of percutaneous vertebroplasty (PVP) guided by X-ray fluoroscopy in treating osteoporotic spinal compression fractures, hemangioma of vertebra and metastatic carcinoma of vertebra.</p><p><b>METHODS</b>One hundred and ninety patients with 275 diseased vertebra underwent PVP under the guidance of C-arm fluoroscopy (male 80, female 110, ranging in age from 53 to 91 years, with an average of 66 years). Bone marrow biopsy needle was inserted percutaneously via transpedicular way into the diseased vertebra. Polymethylmethacrylate (PMMA) was then injected into the diseased vertebra. Visual analogue scale (VAS), mobility and analgesic usage were evaluated pre-operation and 3 months after PVP.</p><p><b>RESULTS</b>PVP was successful in 190 cases (275 vertebrae). VAS was tested by t test at 3 months after PVP (P < 0.05). Simultaneously, scale of patient's mobility and scale of analgesic usage was tested by rank sum test at 3 months after PVP (P < 0.05).</p><p><b>CONCLUSION</b>As the mimimally invasive operation, PVP can alleviate pain in early time, avoid kinds of complications by shortening the patient's time in bed and have the characteristic of simply operative procedure and low expenses. It is an effective mini-invasive technique for osteoporotic spinal compression fractures, hemangioma of vertebra and metastatic carcinoma of vertebra.</p>

Effects of Astragalus membranaceus on atrial dynamics and ANP secretion / 中国中药杂志

<p><b>OBJECTIVE</b>To define the effects of Astragalus membranaceus on the atrial dynamics and ANP secretion in the perfused beating rabbit atria.</p><p><b>METHOD</b>The experiments have been done in isolated perfused beating rabbit atria. ANP was measured by radioimmunoassay in the atrial perfusate in real-time base.</p><p><b>RESULT</b>A. membranaceus (2.0, 2.5, 3.0 g L(-1)) could increase atria stroke volume from (694.70 +/- 0.01) microL g(-1) (P<0.05) to (1,003.00 +/- 8.80) microL g(-1) (P<0.001); (1,120.00 +/- 17.71) microL g(-1) and (1,195.00 +/- 8.21) microL g(-1) (P<0.001), respectively, and its could difference increase atrial pulse pressure from (0.82 +/- 0.01) kPa to (0.86 +/- 0.01) kPa (P<0.01); (0.96 +/- 0.01) kPa (P<0.001) and (1.02 +/- 0.01) kPa (P<0.001), respectively; A. membranaceus obviously increased rabbit atrial dynamics with dose-dependent manner. Simultaneously, A. membranaceus inhibited ANP secretion. Nifedipine (1.0 micromol L(-1)), a L-type Ca2+ channel inhibitor, and KB-R 7943 (10.0 micromol L(-1)), an inhibitor of reversed Na+ -Ca2+ exchanger, blocked the effects of A. membranaceus-induced augmentation of atrial dynamics but failed to modulation the inhibition of A. membranaceus on ANP secretion.</p><p><b>CONCLUSION</b>A. membranaceus increases the atrial dynamics via Na+ -Ca2+ exchanger and L-type Ca2+ channel and negatively modulates ANP secretion in beating rabbit atria.</p>

Cardioprotection against reperfusion injury: updated mechanisms and strategies / 生理学报

Early restoration of blood flow to the ischemic myocardium not only saves myocardium but also induces reperfusion injury. While no specific therapy to reduce reperfusion injury has yet been established, recent laboratory studies have shown that G protein-coupled receptor (GPCR) agonists, insulin, and postconditioning can effectively prevent reperfusion injury in various experimental settings and animal species. The potential mechanisms underlying the cardioprotection initiated by these interventions may include activation of the reperfusion injury salvage kinase (RISK) pathway, inactivation of glycogen synthase kinase 3beta (GSK-3beta), and modulation of mitochondrial permeability transition pore (mPTP) opening. These encouraging laboratory findings may help us develop successful clinical strategies to salvage reperfused myocardium in patients with acute myocardial infarction.

Changes of glutamate and taurine released in the medial vestibular nucleus following acute hypotension / 生理学报

In order to understand whether some special amino acids in the medial vestibular nucleus (MVN) of rats are involved in the regulation of blood pressure, we used microdialysis technique and high performance liquid chromatography (HPLC) to measure the changes of glutamate and taurine in this central area. Acute hypotension was induced by hemorrhage from the femoral artery. It was observed that the basal release of glutamate and taurine in the MVN was stable about 90 min after the beginning of microdialysis. The basal release of glutamate was (18.96 +/- 0.27) pmol/sample (8 mul), and that of taurine was (7.73 +/- 0.05) pmol/sample (8 mul). Glutamate release increased (P<0.05) and taurine release reduced (P<0.05) in the MVN in the hemorrhage-induced acute hypotensive rats. Nevertheless, these changes were not observed in the hemorrhage-induced acute hypotensive rats which were pretreated by infusing 2% lidocaine into the middle ear or 100 mg arsanilic acid into the tympanic cavity. These results suggest that the hemorrhage-induced acute hypotention can influence the activity of the neurons in the MVN by the afferent impulses from vestibular organ, and that some special amino acid transmitters in the MVN are involved in this process.

Effects of Extremely Low Doses of Arginine Vasopressin on the Renal Function in Two-kidney One Clip Goldblatt Hypertensive Rabbit / 대한신장학회잡지

It has been suggested that arginine vasopressin is involved in the acute, but not chronic, regulation of blood pressure. It is still debatable on the role of arginine vasopressin in the development and maintenance of high blood pressure, especially in renal hypertension. This study was performed to examine antidiuretic and renal hemodynamic effects of extremely low doses of arginine vasopressin and the modification of the effects in the early phase of two-kidney one clip Goldblatt hypertensive rabbits. Very low doses(up to 10-20mole/kg/min) of intrarenal arginine vasopressin induced decreases in urine volume, free water clearance, glomerular filteration rate and renal plasma flow(CPAH). The renal effects of arginine vasopressin were dose-dependent. These data indicate that the sensitivity of the kidney to decrease urine volume in response to arginine vasopressin is at least three orders of magnitude higher than previously reported. The renal effects of arginine vasopressin was significantly attenuated by the pretreatment of V2-receptor antagonist. The antidiuretic and renal hemodynamic effects elicited by very low doses of intrarenal arginine vasopressin were suppressed in the contralateral unclipped kidney of two-kidney, one clip Goldblatt hypertensive rabbits. These data suggest that the renal functions can be regulated normally by an extremely low concentration of plasma arginine vasopressin and the regulatory mechanism controlled by the ultralow plasma levels of arginine vasopressin is suppressed in the early phase of two-kidney, one clip Goldblatt hypertension.

Effects of Intrarenal Arterial Infusion of Arginine Vasopressin on the Renal Function and Renin Release in Conscious Rabbits / 대한신장학회잡지

Arginine vasopressin(AVP) released from the posterior pituitary gland is well known to cause an increase in blood pressure, antidiuresis, natriuresis and inhibition of renin secretion. However, the mechanism involved in AVP-induced natriuresis is still unknown. To investigate the mechanism of AVP- induced natriuresis, different doses of AVP were infused into the left renal artery for 10 min and renal function and data were obtained in unanesthetized rabbits. Infusion of different doses of AVP (0.3pg/kg/min-10,000pg/kg/min) caused marked decreases in urine volume, renal blood flow, glomerular filtration rate and free water clearance without changes in blood pressure. Changes in renal function by AVP were not dose-dependent but it took more time for the renal function to recover with increasing doses. Infusion of large doses of AVP(3,000, 10,000pg/kg/min) caused increases in sodium excretion in both kidneys without changes in blood pressure. Infusion of AVP caused a decrease in renin secretion rate. In indomethacin-treated rabbits, changes in urine volume and renal hemodynamics by AVP were markedly accentuated whereas natriuretic effects were attenuated. However, a marked natriuresis caused by AVP in control right kidney still persistently existed. These results suggest that the AVP-induced natriuresis may occur in two-different ways: one is indirect hormonal including prostaglandins and the other is tubular.