Previous studies have suggested that brain stem noradrenergic inputs differentially modulate neurons in the paraventricular nucleus (PVN). Here, we compared the effects of norepinephrine (NE) on spontaneous GABAergic inhibitory postsynaptic currents (sIPSCs) in identified PVN neurons using slice patch technique. In 17 of 18 type I neurons, NE (30-100microM) reversibly decreased sIPSC frequency to 41+/-7% of the baseline value (4.4+/-0.8 Hz, p<0.001). This effect was blocked by yohimbine (2-20microM), an alpha2-adrenoceptor antagonist and mimicked by clonidine (50 microM), an alpha2-adrenoceptor agonist. In contrast, NE increased sIPSC frequency to 248+/-32% of the control (3.06+/-0.37 Hz, p<0.001) in 31 of 54 type II neurons, but decreased the frequency to 41+/-7% of the control (5.5+/-1.3 Hz) in the rest of type II neurons (p<0.001). In both types of PVN neurons, NE did not affect the mean amplitude and decay time constant of sIPSCs. In addition, membrane input resistance and amplitude of sIPSC of type I neurons were larger than those of type II neurons tested (1209 vs. 736 M omega, p<0.001; 110 vs. 81 pS, p<0.001). The results suggest that noradrenergic modulation of inhibitory synaptic transmission in the PVN decreases the neuronal excitability in most type I neurons via alpha2-adrenoceptor, however, either increases in about 60% or decreases in 40% of type II neurons.
Brain Stem ; Clonidine ; Inhibitory Postsynaptic Potentials* ; Membranes ; Neurons ; Norepinephrine ; Paraventricular Hypothalamic Nucleus* ; Synaptic Transmission ; Yohimbine

Cholinergic modulation of GABAergic spontaneous miniature inhibitory postsynaptic currents (mIPSCs) by the activation of muscarine receptors was investigated in mechanically dissociated rat nucleus basalis of the Meynert neurons using the conventional whole-cell patch recording configuration. Muscarine (10microM) reversibly and concentration-dependently decreased mIPSC frequency without affecting the current amplitude distribution. Muscarine action on GABAergic mIPSCs was completely blocked by 1microM methoctramine, a selective M2 receptor antagonist, but not by 1microM pirenzepine, a selective M1 receptor antagonist. NEM (10microM), a G-protein uncoupler, attenuated the inhibitory action of muscarine on GABAergic mIPSC frequency. Muscarine still could decrease GABAergic mIPSC frequency even in the Ca2+-free external solution. However, the inhibitory action of muscarine on GABAergic mIPSCs was completely occluded in the presence of forskolin. The results suggest that muscarine acts presynaptically and reduces the probability of spontaneous GABA release, and that such muscarine-induced inhibitory action seems to be mediated by G-protein-coupled M2 receptors, via the reduction of cAMP production. Accordingly, M2 receptor-mediated disinhibition of nBM neurons might play one of important roles in the regulation of cholinergic outputs from nBM neurons as well as the excitability of nBM neurons themselves.
Animals ; Cholinergic Neurons ; Colforsin ; gamma-Aminobutyric Acid ; GTP-Binding Proteins ; Inhibitory Postsynaptic Potentials ; Muscarine* ; Neurons* ; Pirenzepine ; Rats*

The renoprotective activities of white ginseng radix and rootlet were compared in spontaneously hypertensive rat (SHR) with diabetes. During oral administration of white ginseng radix (Ginseng Radix Alba, GRA) and white ginseng rootlet (Ginseng Radix Palva, GRP) for four weeks, arterial blood pressure and blood glucose levels were determined at every 10 days. In both GRA- and GRP-treatment groups, arterial blood pressures started to go down after 10 days of administration and maintained throughout the study period. After four weeks administrations of GRA and GRP, diastolic blood pressures were significantly decreased with 17% and 9%, respectively. GRA treatment also decreased blood glucose levels after 10 days of administration when compared with diabetic SHR group. At the end of the experiment, serum creatinine (Scr) and blood urea nitrogen (BUN) were not significantly different between the groups, except 62% higher value of BUN in diabetic SHR group when compared with SHR group. In the diabetic SHR group, the excretion of urinary albumin was increased significantly when compared with SHR. The level of urinary albumin in GRA treated group was markedly reduced when compared with diabetic SHR group (67.8 4.7 vs. 131.3 13.5 mg/24 h). To examine the effects of ginseng radices on an overt diabetic nephropathy, index of kidney hypertrophy and transforming growth factor-beta1 (TGF-beta1) protein levels were evaluated. The glomerular and tubular cells stained positive for TGF-beta1 seemed to be more abundant in diabetic SHR than in those with SHR, and GRA treated rats showed somewhat less TGF-beta1 protein in glomerular and tubular cells when compared with diabetic SHR. Our results suggest that GRA might be a useful antihypertensive and antidiabetic agent with renoprotective effect.
Administration, Oral ; Animals ; Arterial Pressure ; Blood Glucose ; Blood Urea Nitrogen ; Creatinine ; Diabetic Nephropathies ; Hypertrophy ; Kidney ; Panax* ; Rats ; Rats, Inbred SHR* ; Transforming Growth Factor beta1

An ex vivo assay determining the flavin-containing monooxygenase (FMO) activity in perfused rat liver has been developed by assessing the rate of thiobenzamide S-oxide (TBSO) formation from the infused thiobenzamide (TB). The hepatotoxicity by TB or TBSO was not a critical factor for maintaining the FMO activity for up to 50 min. The FMO activity expressed in nmoles TBSO produced/g liver/min was the same for the recycling and non-recycling perfusion. This implies that reduction of the oxidized TBSO back to the parent compound (TB) is negligible. Hydrolysis of the collected perfusates with either beta-glucuronidase or arylsulfatase did not increase the TBSO level and thus, TBSO does not appear to undergo conjugation either to glucuronide or sulfate esters. Thus, measuring the rate of TB S-oxidation in the isolated perfused liver with 1 mM TB for 50 min provides a useful tool for evaluation of the hepatic FMO activity in the absence of hepatic necrosis and without the interferences caused by further conjugation or back reduction of the TBSO to the parent TB.
Animals ; Esters ; Glucuronidase ; Humans ; Hydrolysis ; Liver* ; Necrosis ; Parents ; Perfusion ; Rats* ; Recycling

This study was undertaken to examine the effects of ultraviolet light (UVL) and rebamipide on the cutaneous blood flow and tissue survival on rabbit skin flap. In a random bipedicle flap, Laser Doppler Flowmetry (LDF) was employed to measure the blood flow of flap (BFF). Wound Margin Strength (WMS) measured by force transducer and Light microscopy were used for evaluation of tissue viability. Single exposure to UVL increased the BFF gradually for more than 15 hours, and decreased the vasoconstrictor effect of intravenous phenylephrine. The UVL-induced increase in BFF regressed after 18 hours of irradiation, and this regression was tended to be enhanced by intradermal injection of L-NAME, a nitric oxide synthase (NOS) inhibitor, but the regression was significantly reversed by acetylcholine, an endothelial constitutive NOS (cNOS) activator and L-arginine, an NO precursor. Rebamipide, a novel antiulcer oxide synthase (NOS) inhibitor, but the regression was significantly reversed by acetylcholine, an endoagent known to scavenge the hydroxyl radical, abruptly reversed the spontaneous regression of the UVL-induced increase in BFF by the same manner as L-arginine. In ischemic skin flap, rebamipide increased the BFF abruptly by the same manner as sodium nitroprusside (SNP), an NO doner, while N-acetylcystein (NAC), a free radical scavenger, gradually increase the BFF. The rebamipide-induced increase in BFF was sustained at the level of the SNP-induced increase in BFF during the late period of experiment. Rebamipide increased the WMS of skin flaps and prevented the tissue necrosis in comparison with L-NAME. Based on these results, it is concluded that in rabbit skin, UVL irradiation increases the BFF by NO release, and rebamipide exerts a protective effect on the viability of ischemic skin flaps by either or both the increase in BFF by NO release and free radical scavenger effect.
Acetylcholine ; Arginine ; Hydroxyl Radical ; Injections, Intradermal ; Laser-Doppler Flowmetry ; Microscopy ; Necrosis ; NG-Nitroarginine Methyl Ester ; Nitric Oxide ; Nitric Oxide Synthase ; Nitroprusside ; Phenylephrine ; Skin* ; Tissue Survival ; Transducers ; Ultraviolet Rays ; Wounds and Injuries

In this report, the inhibitory action of eupatilin was investigated by using leukotriene D4 in the human neutrophils and Kato III cells (Gastric adenoma cells as a substitute for gastric mucosal cells) stimulated by Helicobacter pylori. Leukotriene D4 (LTD4) was released from both neutrophils and Kato III cells when these cells were incubated with H. pylori. The release of LTD4 increased time-dependently and the maximum release of LTD4 was 2.3-2.5 pmol. But in the presence of eupatilin, the release of LTD4 from these cells was inhibited in a dose-dependent manner. In the neutrophils, die release of LTD4 was suppressed to 70% and 50% of the control levels when neutrophils was incubated with 0.01 and 0.1 mM of eupatilin. In the Kato III cells, the release of LTD4 was suppressed to 59% and 27% of the control levels by adding 0.01 and 0.1 mM of eupatilin. We estimated the intracellular Ca2+ levels when Kato III cells and neutrophils were stimulated by H. pylori using 45Ca. But the suppressive effect of eupatilin on Ca2+ influx into these cells was not significant. We also obtained the results that H. pylori induced Ca2+ influx into these cells by confocal microscopy, however there was no differences in the dose level of eupatilin. These results were confirmed by 1H Nuclear Magnetic Resonance(NMR) spectroscopy. The NMR patterns of eupatilin in the absence of Ca2+ was changed compare with when Ca2+ was present, but its effect was not strong.
Adenoma ; Helicobacter pylori ; Helicobacter* ; Humans* ; Leukotriene D4* ; Microscopy, Confocal ; Neutrophils* ; Spectrum Analysis

In the freshly isolated rat nephron, the effect of endothelin-1, -2 and -3 (ET-1, -2 and -3) on cytosolic free calcium concentration ((Ca2+)i) was determined using the fluorescent indicator Fura-2/AM. (Ca2+)i increase was investigated in 9 parts of the single nephron including glomerulus (Glm), S1, S2, S3, Cortical and medullary thick ascending limb and cortical (CCT) and outer medullary collecting tubule (OMCT). Endothelins increased (Ca2+)i in Glm (ET-1; 127+/-17%, ET-2; 93+/-5%, ET-3; 169+/-17%), CCT (ET-1; 30+/-6%, ET-2; 38+/- 19%, ET-3; 158+/-18%) and OMCT (ET-1; 197+/- 11%, ET-2; 195+/- 11%, ET-3; 215+ 37%) at 10(-7) M. In OMCT, ET-1 and ET-2 increased (Ca2+)i in a dose-dependent manner (10(-10) ~ 10(-6) M). To the contrary, ET-3-induced (Ca2+)i rise was begun from 10(-12) M. BQ-123Na, an antagonist of ETA receptor, at 10(-4) M inhibited about 30% of (Ca2+)i rise induced by ET-1 and -3. Binding experiments using (125I)ET-3 showed the existence of ETB receptor in OMCT. This binding was replaced by ET-1, ET-2 or ET-3 by the almost same degree but not by angiotensin II or vasopressin.
Angiotensin II ; Animals ; Calcium* ; Cytosol ; Endothelin-1 ; Endothelin-2 ; Endothelins* ; Extremities ; Nephrons* ; Rats* ; Vasopressins

The effects of pH on K+ currents were investigated in single smooth muscle cells isolated from the thoracic aorta of Wistar-Kyoto rats. Whole-cell K+ currents were recorded in the conventional configuration of the voltage-clamp technique. Pinacidil (10muM) activated the whole-cell current and the pinacidil-activated current was completely inhibited by glibenclamide (10muM), an inhibitor of ATP-sensitive K+ channel (KATP channel). Pinacidil-activated current was reversed at near the K+ equilibrium potential. This current was time- and voltage-independent and reduced by elevating intracellular ATP. Pinacidil-activated current was reduced by lowering the external pH. However, alteration of internal pH has controversial effects on pinacidil-activated current. When the single cell was dialyzed with 0.1 mM ATP, alteration of internal pH had no effect on pinacidil-activated K+ current. In the contrast, when the single cell was dialyzed with 3 mM ATP, pinacidil-activated current was increased by lowering internal pH. Our results suggest that K+ channel activated by pinacidil may be KATP channel and internal H+ may reduce the inhibitory effect of ATP on KATP channel.
Adenosine Triphosphate ; Animals ; Aorta, Thoracic ; Glyburide ; Hydrogen-Ion Concentration* ; Muscle, Smooth* ; Muscle, Smooth, Vascular ; Myocytes, Smooth Muscle* ; Patch-Clamp Techniques ; Pinacidil ; Rats*

It has been known that activation of tyrosine kinases is involved in signal transduction. Role of the tyrosine kinase in vascular smooth muscle contraction was examined in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. Male Sprague-Dawley rats underwent uninephrectomy, one week after which they were subcutaneously implanted with DOCA (200 mg/kg) and supplied with 1% NaCl and 0.2% KCl drinking water for 4-6 weeks. Control rats were treated the same except for that no DOCA was implanted. Helical strips of carotid arteries were mounted in organ baths for measurement of isometric force development. Genistein was used as a tyrosine kinase inhibitor. Concentration-response curves to 5-hydroxytryptamine (5-HT) shifted to the right by genistein in both DOCA-salt hypertensive and control rats. Although the sensitivity to genistein was similar between the two groups, the maximum force generation by 5-HT was less inhibited by genistein in arteries from DOCA-salt hypertensive rats than in those from controls. Genistein-induced relaxations were attenuated in arteries from DOCA-salt rats. Genistein affected the contraction to phorbol 12, 13-dibutyrate (PDBu) neither in DOCA-salt nor in control arteries. These observations suggest that tyrosine kinase is involved in 5-HT-induced vascular contraction, of which role is reduced in DOCA-salt hypertension.
Animals ; Arteries ; Baths ; Carotid Arteries ; Desoxycorticosterone Acetate ; Desoxycorticosterone* ; Drinking Water ; Genistein ; Humans ; Hypertension ; Male ; Muscle, Smooth, Vascular ; Phosphotransferases* ; Protein-Tyrosine Kinases ; Rats* ; Rats, Sprague-Dawley ; Relaxation ; Serotonin ; Signal Transduction ; Tyrosine*

It has been postulated that the intracellular taurine is co-transported with Na+ down a concentration gradient and prevents the intracellular accumulation of sodium. It is therefore, expected that an elevated level of intracellular taurine prevents the sodium-promoted calcium influx to protect the cellular damages associated with sodium and calcium overload. In the present study, we evaluated the effects of intra- and extracellular taurine on the myocardial Na+ and Ca++ contents and the cardiac functions in isolated rat hearts which were loaded with sodium by monensin, a Na+/-ionophore. Monensin caused a dose-dependent increase in intracellular Na+ accompanied with a subsequent increase in intracellular Ca++ and a mechanical dysfunction. In this monensin-treated heart, myocardial taurine content was decreased with a concomitant increase in the release of taurine. The monensin-induced increases in intracellular Na+, Ca++ and depression of cardiac function were prevented in the hearts of which taurine content had been increased by high-taurine diet. Conversely, in the hearts of which taurine concentration gradient had been decreased by addition of taurine in the perfusate, the monensin-induced increases in Na+, Ca++ and functional depression were accelerated. These results suggest that taurine, depending on the intra-extracellular concentration gradient, can affect intracellular sodium and calcium concentrations, and that an increased intracellular taurine may play a role in protection of myocardial dysfunction associated with the sodium and calcium overload.
Animals ; Calcium ; Depression ; Diet ; Heart* ; Monensin ; Rats* ; Sodium ; Taurine*