To investigate the possible involvement of outward potassium (K+) currents in nitric oxide-induced relaxation in intestinal smooth muscle, we used whole-cell patch clamp technique in freshly dispersed guinea-pig ileum longitudinal smooth muscle cells. When cells were held at -60 mV and depolarized from - 40 mV to + 50 mV in 10 mV increments, sustained outward K+ currents were evoked. The outward K+ currents were markedly increased by the addition of 10 muM sodium nitroprusside (SNP). 10 muM S-nitroso-N-acetylpenicillamine (SNAP) and 1 mM 8-Bromo-cyclic GMP (8-Br-cGMP) also showed a similar effect to that of SNP. 1 mM tetraethylammonium (TEA) significantly reduced depolarization-activated outward K+ currents. SNP-enhanced outward K+ currents were blocked by the application of TEA. High EGTA containing pipette solution (10 mM) reduced the control currents and also inhibited the SNP-enhanced outward K+ currents. 5 mM 4-aminopyridine (4-AP) significantly reduced the control currents but showed no effect on SNP-enhanced outward K+ currents. 0.3 muM apamin and 10 muM glibenclamide showed no effect on SNP-enhanced outward K+ currents. 1 muM 1H-(1,2,4)oxadiazolo (4,3-a)quinoxaline-1-one (ODQ), a specific inhibitor of soluble guanylate cyclase, significantly blocked SNP-enhanced K+ currents. We conclude that NO donors activate the Ca2+-activated K+ channels in guinea-pig ileal smooth muscle via activation of guanylate cyclase.
4-Aminopyridine ; Apamin ; Egtazic Acid ; Glyburide ; Guanylate Cyclase ; Humans ; Ileum* ; Muscle, Smooth* ; Myocytes, Smooth Muscle* ; Nitric Oxide* ; Nitroprusside ; Potassium Channels, Calcium-Activated ; Potassium* ; Relaxation ; S-Nitroso-N-Acetylpenicillamine ; Tea ; Tetraethylammonium ; Tissue Donors

OBJECTIVE: It is a widely accepted belief that paraspinal muscles tend to show spontaneous activity on needle electromyography early on in a radiculopathy and distal muscles become abnormal later on. But most studies have shown the limitations of using symptom duration when interpreting electrodiagnostic findings in radiculopathy. The purpose of this study was to determine the relationship between symptom duration and abnormal spontaneous activity in S1 radiculopathy confined to abnormal H-reflex. METHOD: A retrospective study that collected the informations on symptom duration and spontaneous activity in paraspinal muscle and gastrocnemius for 112 patients with S1 radiculopathy diagnosed by unilateral H-reflex abnormality was undertaken. RESULTS: Abnormal spontaneous activity in paraspinal muscle had shown a significant negative correlation with symptom duration, that is a tendency to decrease its expression over symptom duration. On the contrary abnormal spontaneous activity in gastrocnemius muscle was rare at first a few weeks and became to show after 7 weeks. Patients with symptom duration over 1 year had higher incidence of having no abnormal spontaneous activities both in paraspinal and gastrocnemius muscle. CONCLUSION: These results suggested that symptom duration had a potential role in the diagnosis of S1 radiculopathy when H-reflex were abnormal unilaterally.
Diagnosis ; Electromyography ; H-Reflex ; Humans ; Incidence ; Muscle, Skeletal ; Muscles ; Needles ; Paraspinal Muscles ; Radiculopathy* ; Retrospective Studies

The present study were designed to characterize the action mechanisms of acetylcholine (ACh) -induced endothelium-dependent relaxation in arteries precontracted with high K (70 mM). For this, we simultaneously measured both muscle tension and cytosolic free Ca2 concentration ([Ca2 ]i), using fura-2, in endothelium-intact, rabbit carotid arterial strips. In the artery with endothelium, high K increased both [Ca2 ]i and muscle tension whereas ACh (10microM) significantly relaxed the muscle and increased [Ca2 ]i. In the presence of NG-nitro-L-arginine (L-NAME, 0.1 mM), ACh increased [Ca2 ]i without relaxing the muscle. In the artery without endothelium, high K increased both [Ca2 ]i and muscle tension although ACh was ineffective. 4-DAMP (10 nM) or atropine (0.1microM) abolished ACh-induced increase in [Ca2 ]i and relaxation. The increase of [Ca2 ]i and vasorelaxation by ACh was siginificantly reduced by either 3microM gadolinium, 10microM lanthanum, or by 10microM SKF 96365. These results suggest that in rabbit carotid artery, ACh-evoked relaxation of 70 mM K -induced contractions appears to be mediated by the release of NO. ACh-evoked vasorelaxation is mediated via the M3 subtype, and activation of the M3 subtype is suggested to stimulate nonselective cation channels, leading to increase of [Ca2 ]i in endothelial cells.
Acetylcholine ; Arteries ; Atropine ; Carotid Arteries* ; Cytosol ; Endothelial Cells ; Endothelium ; Fura-2 ; Gadolinium ; Lanthanum ; Muscle Tonus ; Nitric Oxide ; Nitroarginine ; Relaxation* ; Vasodilation

Tonic smooth muscle exhibit the latch phenomenon: high force at low myosin regulatory light chains (MRLC) phosphorylation, shortening velocity (Vo), and energy consumption. However, the kinetics of MRLC phosphorylation and cellular activation in phasic smooth muscle are unknown. The present study was to determine whether Ca(2+)-stimulated MRLC phosphorylation could suffice to explain the agonist- or high K(+)-induced contraction in a fast, phasic smooth muscle. We measured myoplasmic [Ca2+], MRLC phosphorylation, half-time after step-shortening (a measure of Vo) and contractile stress in rabbit urinary bladder strips. High K(+)-induced contractions were phasic at both 22degrees C and 37degrees C: myoplasmic [Ca2+], MRLC phosphorylation, 1/half-time, and contractile stress increased transiently and then all decreased to intermediate values. Carbachol (CCh)-induced contractions exhibited latch at 37degrees C: stress was maintained at high levels despite decreasing myoplasmic [Ca2+], MRLC phosphorylation, and 1/half-time. At 22degrees C CCh induced sustained elevations in all parameters. 1/half-time depended on both myoplasmic [Ca2+] and MRLC phosphorylation. The steady-state dependence of stress on MRLC phosphorylation was very steep at 37degrees C in the CCh- or K(+)-depolarized tissue and reduced temperature flattend the dependence of stress on MRLC phosphorylation compared to 37degrees C. These data suggest that phasic smooth muscle also exhibits latch behavior and latch is less prominent at lower temperature.
Carbachol ; Contracts ; Kinetics ; Muscle, Smooth ; Myosin Light Chains ; Phosphorylation ; Urinary Bladder

Background/Aims: This study was conducted to investigate the inhibitory effect of irsogladine maleate (IM) on gastric ulcers induced by ethanol and hydrochloric acid (HCl). Methods: Mice were pretreated with IM for 1 hours before ulcer induction. Gastric ulcers were induced by oral administration of an ethanol/HCl mixture. To clarify the action mechanism of IM, the roles of 3ʹ5ʹ-cyclic adenosine monophosphate (cAMP), nitric oxide (NO), adenosine triphosphate-sensitive potassium (KATP ) channels, prostaglandins and transient receptor potential cation channel subfamily V member 1 (TRPV1) were investigated, and lipid peroxidation in the stomach of IM-treated and -untreated animals was also measured. Results: IM significantly reduced the extent of ethanol/HCl mixture-induced gastric ulceration. It exhibited dose-related gastroprotection against the ethanol/ HCl-induced lesions, while pretreatment with glibenclamide but not N(ω)-nitro-L-arginine methyl ester, reversed this action. While pretreatment with the TRPV1 antagonist capsazepine failed to effectively block the gastroprotective effect of IM, the non-selective cyclooxygenase inhibitor indomethacin almost abolished it. IM also decreased the level of thiobarbituric acid reactive substances. Conclusions We concluded that IM exhibited significant gastroprotective effects in an ethanol/HCl-induced ulcer model, which appear to be mediated, at least in part, by NO, cAMP, endogenous prostaglandins, KATP channel opening, activation of TRPV1 channels, and antioxidant properties.

No abstract available.
Lipoma*

No abstract available.

The relationship between the level of testosterone and the incidence of coronary heart disease is still controversial in the view of the results of clinical and epidemiologic studies. This uncertainty might be partly due to relatively small number of experimental studies undertaken to investigate the cellular mechanism underlying the vascular responses to testosterone. To further investigate the cellular mechanisms of testosterone with respect to vascular response, we investigated the effect of testosterone on contractility and intracellular Ca2+ regulation in a rabbit coronary artery and evaluated the underlying mechanism of testosterone-induced changes of coronary vascular tone by using various pharmacological blockers. Testosterone was found to relax rabbit coronary arteries in a dose-dependent manner, and no significant difference was found in the relaxation response to testosterone with or without endothelium. Similar results were obtained in male and non-pregnant female rabbit coronary arteries. The relaxation response of rabbit coronary arteries to testosterone was greater for PGF2alpha-contracted rings than for KCl contracted rings, which suggest the involvement of K+ channels. Furthermore, the relaxation response to testosterone was significantly reduced by 4-aminopyridine, a sensitive blocker of voltage dependent K+ channels, but not by low doses of tetraethylammonium or iberiotoxin, a Ca2+ activated K+ channel blocker. Testosterone simultaneously reduced the intracellular Ca2+ concentration ([Ca2+]i) and tension, and 4-AP effectively antagonized the testosterone-induced change of [Ca2+]i and tension. Therefore, it may be concluded that the stimulation of voltage dependent K channels is responsible, at least in part, for the testosterone-induced relaxation of rabbit coronary arteries.
Androgens/*pharmacology ; Animals ; Arteries/drug effects ; Calcium/*metabolism ; Coronary Vessels/*drug effects ; Female ; Intracellular Membranes/*metabolism ; Male ; Osmolar Concentration ; Potassium Channels, Voltage-Gated/drug effects/*metabolism ; Rabbits ; Support, Non-U.S. Gov't ; Testosterone/*pharmacology ; *Vasodilation

PURPOSE: Many studies on the time course of inducible nitric oxide synthase (iNOS) gene expression have been performed in the LPS (Lipopolysaccharide)-induced endotoxemic model, but there have been few experimental approaches to continuous peritonitis-induced sepsis model. We conducted this study to establish basic data for future sepsis-related research by investigating the time course of iNOS gene expression and the relationship with the production of inflammatory mediators in the early sepsis model induced by cecal ligation and puncture (CLP). METHODS: Male Sprague-Dawley rats were operated on by sing the CLP method to induce of peritonitis; and then, they were sacrificed and samples of blood and lung tissues were obtained at various times (1,2,3,6,9 and 12 h after CLP). We observed the expression of iNOS mRNA from lung tissues and measured the synthesis of nitric oxide, IL-1beta , and TNF-alpha from the blood. RESULTS: iNOS mRNA began to be expressed at 3 h and was maintained untill 12 h after CLP. The nitric oxide concentration was increased significantly at 6 h, reached its peak level at 9 h, and maintained a plateau untill 12 h after CLP. TNF-alpha began to be detected at 3 h, increased gradually, and decreased steeply from 9 h after CLP. IL-1beta showed its peak level at 6 h after CLP, and tended to decrease without significance. CONCLUSION: We observed that the iNOS gene was expressed later in peritonitis-induced sepsis than in LPSinduced sepsis. Nitric oxide and key inflammatory mediators were also expressed later in peritonitis-induced sepsis than in LPS-induced sepsis.
Animals ; Gene Expression ; Humans ; Inflammation Mediators ; Ligation ; Lung ; Male ; Nitric Oxide ; Nitric Oxide Synthase ; Nitric Oxide Synthase Type II ; Peritonitis ; Punctures ; Rats ; Rats, Sprague-Dawley ; RNA, Messenger ; Sepsis ; Tumor Necrosis Factor-alpha

PURPOSE: To assess the usefulness of Gd-DTPA MRI in the evaluation of the characteristics of intracranial meningiomas and in the correlation with their histopathologic pattern. MATERIALS AND METHODS: We retrospectively analyzed the Gd-DTPA MRI findings in 22 cases of histologicalty-proven intracranial meningiomas. The images were assessed for signal intensity, internal texture, peritumoral edema, and enhancement characteristics. Computed tomograms were obtained in 18 cases and compared with MRI findings. RESULTS: Tl-weighted images were not particularly useful for discriminating pathologic subtype, but signal intensity on T2-weighted images were relatively well correlated with histopathologic findings. A heterogeneous texture produced by tumor vascularity, calcification, cystic foci, hemorrhagic necrosis, or psammoma body was relatively well shown on Gd-DTPA Tl-weighted image compared with that on T1- or T2-weighted image. Gd-DTPA Tl-weighted images revealed a dural tail sign in 19 cases(83%). Angioblastic type was slightly hypointense on Tl-weighted image and markedly hyperintense on T2-weighted image. Psammomatous type and firboblastic type were isointense on both T1- and T2-weighted image. Fibroblastic type was more densely enhanced than the other. The transitional, atypical, and papillary types showed tendency of heterogeneous enhancement. CONCLUSION: Gd-DTPA MRI was a useful imaging modality in evaluation of the characteristics of meningiomas and correlated well with the pathologic patterns.
Edema ; Fibroblasts ; Gadolinium DTPA* ; Magnetic Resonance Imaging* ; Meningioma ; Necrosis ; Retrospective Studies