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General Physiology and Biophysics

Volume 29, 2010, No. 4


  Nitric oxide – the endothelium-derived relaxing factor and its role in endothelial functions
Viktor Bauer 1), Ruzena Sotnikova

1)Institute of Experimental Pharmacology and Toxicology , Slovak Academy of Scieneces, Dúbravská cesta 9, 841 04 Bratislava, Slovakia.

Vascular endothelium plays a key role in the local regulation of vascular tone and vascular architecture by release of vasodilator and vasoconstrictor substances, as well as factors with pro-coagulant, anticoagulant, fibrinolytic, antibacterial properties, growth factors, chemokines, free radicals, etc. Release of endothelium-derived relaxing factors such as nitric oxide (NO), prostaglandins and endothelium-derived hyperpolarizing factor, as well as vasoconstricting factors such as endothelin, superoxide and thromboxanes play an influential role in the maintenance and regulation of vascular tone and the corresponding peripheral vascular resistance. Under physiological conditions, the release of anticoagulant and smooth muscle relaxing factors exceeds the release of other substances. The first part of this review presents the functions of the endothelium itself, the nature of the endothelium-derived relaxing factor, its production by NO synthases, mechanisms of its action via activation of soluble guanylyl cyclase and production of cyclic 3'-5'-guanosine monophosphate. The resulting biological effects include vasodilatation, regulation of vessel wall structure, increased regional blood perfusion, lowering of systemic blood pressure, antithrombosis and antiatherosclerosis effects, which counteract the vascular actions of endogenous vasoconstrictor substances. Impaired endothelial function, either as a consequence of reduced production/release or increased inactivation of endothelium-derived vasodilators, as well as interactions of NO with angiotensin, reactive oxygen species and oxidized lipoproteins, has detrimental functional consequences and is one of the most important cardiovascular risk factors. Therefore the second part of this review assesses the pathophysiologic impact of the endothelium in examples of cardiovascular pathologies, e.g. endotheliopathies caused by increased angiotensin production, lipid peroxidation, ischemia/reperfusion or diabetes.

General Physiology and Biophysics. Volume 29, 2010, No. 4: 319-340.

  Uphill and downhill water transport in rat glioma cells
Béatrice Rouzaire-Dubois 1), Jean Dubois

1)CNRS, Institut de Neurobiologie Alfred Fessard-FRC2118, Laboratoire de Neurobiologie Cellulaire et Moléculaire-FRE 3295, Gif sur Yvette, F-91198, France.

The cell water content determines the cell volume, which in turn controls numerous cellular functions. The mean volume of rat glioma cells was electronically measured under isotonic and anisotonic conditions. Two types of isotonic solutions were used containing either high or low concentrations of NaCl, KCl or N-methylglucamineCl. In low salt solutions, osmolarity was maintained constant by the addition of sucrose or mannitol. Anisotonicity was induced by changing the concentration of electrolytes. As expected, the cell volume increased when the concentration of electrolytes was decreased from a high (165 mM) monovalent cation concentration. In contrast, the cell volume decreased when the concentration of electrolytes was decreased from a low (85 mM) monovalent cation concentration. Reciprocally and unexpectedly, the cell volume increased during a hyperosmotic challenge when the initial cation concentration was low, whereas it decreased when the initial cation concentration was high. These opposite volume changes observed during similar anisotonic challenges but starting from different electrolyte concentrations provide the first evidence that H2O is not only passively transported (downhill) through aquaporins but also follows ion fluxes (uphill).

General Physiology and Biophysics. Volume 29, 2010, No. 4: 341-345.

  Sex differences in social stress-induced pressor and behavioral responses in normotensive and prehypertensive rats
Iveta Bernatova 1), Angelika Puzserova, Michal Dubovicky

1)Institute of Normal and Pathological Physiology, Slovak Academy of Sciences, Sienkiewiczova 1, 813 71 Bratislava, Slovakia.

This study investigated sex differences in chronic social stress-induced pressor and behavioral responses in normotensive and prehypertensive rats. Adult Wistar and borderline hypertensive (BH) rats (offspring of Wistar dams and spontaneously hypertensive sires) of both sexes were exposed to crowding stress (200 cm²/rat, 5 rats/cage) for 6 weeks. Controls were kept 4 rats/cage (480 cm²/rat). Blood pressure (BP) and open field activity were determined before experiment and after 1, 3 and 6 weeks of stress. Basal BP of BH rats was higher than in Wistar (p < 0.001) in both males and females. Horizontal and vertical activity of BH males and females was elevated vs. Wistar (p < 0.01) and females in both phenotypes were more active than the respective males (p < 0.01). Crowding resulted in delayed between-session habituation and significant elevation of BP only in BH males (143 ± 2 vs. 134 ± 3 mmHg in controls after 6-week crowding). No changes of BP were observed in crowded females of both phenotypes regardless of their delayed between-session habituation. Thus chronic social stress produced by crowding seems to represent a significant risk factor for development of stress-related hypertension only in males with genetic predisposition to high blood pressure while females of both phenotypes responded to stress by impaired between-session habituation.

General Physiology and Biophysics. Volume 29, 2010, No. 4: 346-354.

  Interaction of long-chain n-alcohols with fluid DOPC bilayers: a neutron diffraction study
Viktor Petrenko 1), Mária Klacsová, Anatoly Beskrovnyy, Daniela Uhrikova, Pavol Balgavý

1)Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia.

Lamellar phases composed of fluid dioleoylphosphatidylcholine (DOPC) bilayers containing alkan-1-ols (CnOH, n = 8, 10, 14, 16, 18 is the number of carbon atoms) at CnOH : DOPC = 0.3 molar ratio and hydrated with heavy water at 20.2 ≥ D2O : DOPC ≥ 14.4 molar ratio were studied by neutron diffraction. The bilayer thickness dL and the bilayer surface area AL per DOPC at the bilayer-water interface were obtained from the lamellar repeat period d using molecular volumes of DOPC, CnOH and D2O, and the Luzatti’s method. Both the dL and AL increase with the CnOH chain length n at CnOH : DOPC = 0.3 molar ratio: dL = (3.888 ± 0.066) + (0.016 ± 0.005)·n (in nm), AL = (0.6711 ± 0.0107) + (0.0012 ± 0.0008)·n (in nm²).

General Physiology and Biophysics. Volume 29, 2010, No. 4: 355-361.

  The application of the RT-PCR method for the staging of the prostate cancer progression
Anezka Zummerova 1), Peter Labas, Daniel Bohmer, Milan Blasko, Stefan Polak, Lubos Danisovic, Vanda Repiska

1)Department of Pathology and Forensic Medicine, Health Care Surveillance Authority, Antolska 11, 851 07 Bratislava, Slovakia.

Molecular biology seems to bring more convincing markers for the detection of prostate cancer as well as the development of metastases than immunohistochemistry. The main goal of present work was to detect the expression of prostate specific antigen (PSA) and prostate-specific membrane antigen (PSM) genes in the micrometastases by the RT-PCR to assess the progression of prostate cancer. We analyzed 50 patients: 28 patients with clinically localized or locally advanced prostate cancer who underwent radical prostatectomy, 7 patients with clinically proven metastases, 8 patients with benign prostatic hyperplasia, and 7 healthy young men. The results of RT-PCR in the first group of 28 patients varied, however, they were in good correlation with the health status of the patients. Positive results of PSA and notably for PSM were good predictors of beginning metastasing process. Seven patients with metastatic disease had positive RT-PCR results both for PSA and PSM. All of the patients with benign prostatic hyperplasia and healthy young men had negative RT-PCR results for PSA and PSM. The study showed that positive RT-PCR results for PSA and especially for PSM correlated well with the progression of the disease and negative results reflected good health status of the patients.

General Physiology and Biophysics. Volume 29, 2010, No. 4: 362-372.

  Influence of sodium nitroprusside on human erythrocyte membrane water permeability: an NMR study
Gojmir Lahajnar 1), Barbara Sobotič, Ana Sepe, Vojko Jazbinšek, Slavko Pečar

1)J. Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia. gojmir.lahajnar@

Sodium nitroprusside (SNP) is a nitric oxide (•NO) donor in vitro and in vivo. In this paper the time variation of the intracellular water proton nuclear magnetic resonance (NMR) effective relaxation time T'2a in SNP-treated human erythrocyte suspensions, containing 10 mM membrane impermeable paramagnetic MnCl2, has been measured. The observed T'2a time-course was analyzed in terms of the two mechanisms by which released •NO affects T'2a. These are, respectively, enhancement of the intracellular water proton intrinsic NMR relaxation rate 1/T2a by paramagnetism of •NO subsequently bonded to iron atoms of intracellular deoxyhemoglobin, and suppression of diffusional water permeability Pd as a consequence of nitrosylation of aquaporin-1 (AQP1) channel Cys189, either by direct reaction with •NO or with one of the •NO oxidation products, such as N2O3. The bound •NO on the Cys189 thiol residue appears to impose a less efficient barrier to water permeation through AQP1 than the larger carboxyphenylmercuryl residue from p-chloromercuribenzoate. The effect of •NO on Pd is discussed in terms of NO-induced vasodilation.

General Physiology and Biophysics. Volume 29, 2010, No. 4: 373-380.

  Haloperidol increases expression of the inositol 1,4,5-trisphosphate receptors in rat cardiac atria, but not in ventricles
Marie Novakova 1), Barbora Sedlakova, Marta Sirova, Katerina Fialova, Olga Krizanova

1)Department of Physiology, Faculty of Medicine, Masaryk University, Komenského nám. 2, Brno, Czech Republic.

Numerous ligands of sigma receptors are known to prolong the QT interval and therefore cause a variety of arrhythmias. High affinity binding sites for the prototypical sigma ligand haloperidol were found in membranes of cardiac myocytes from adult rats. Activation of sigma 1 receptor leads to a release of calcium from the endoplasmic reticulum that follows increased synthesis of inositol 1,4,5-trisphosphate (IP3). We studied the effect of long-term haloperidol treatment on the expression of sigma 1 receptors, IP3 receptors of type 1 and 2 in the individual parts of the rat heart, in isolated rat cardiomyocytes and in PC12 cells. We have found that prolonged treatment with haloperidol significantly increased mRNA levels of sigma 1 receptors in both atria and ventricles. Sigma 1 receptor’s mRNA was increased also in isolated cardiomyocytes. Haloperidol treatment affects the expression of IP3 receptors of type 1 and 2 in cardiac atria, but not in cardiac ventricles. We observed increase in IP3 receptors in differentiated PC12 cells, but not in isolated cardiomyocytes. We propose that this increase might participate in triggering cardiac arrhythmias during haloperidol treatment, which has to be further verified.

General Physiology and Biophysics. Volume 29, 2010, No. 4: 381-389.

  Time-dependent effects of exposure to static magnetic field on glucose and lipid metabolism in rat
Aida Lahbib 1), Myriam Elferchichi, Soumaya Ghodbane, Hatem Belguith, Sihem Chater, Mohsen Sakly, Hafedh Abdelmelek

1)Laboratoire de Physiologie Integrée, Faculté des Sciences de Bizerte, 7021 Jarzouna, Tunisia.

In the following study, we investigate the effects of static magnetic field (SMF) (128 mT, 1 h/day during 5 or 15 consecutive days) on anthropometric parameters, glucose and lipid metabolism in rats. Exposure to SMF during 5 days induced a decrease (–8%, p < 0.05) in relative liver weight and serum insulin concentration (–56%, p < 0.001), while blood glucose level was increased (+10%, p < 0.001). By contrast, the same treatment failed to alter body weight, relative kidney weight and levels of lactate, cholesterol, triglycerides and phospholipids. Exposure to SMF during 15 days induced a decrease (–15 %, p < 0.001) in body weight, liver weight (–15 %, p < 0.05), insulin concentration (–63%, p < 0.001), plasmatic lactate level (–55%, p < 0.05) and increased glucose (+24%, p < 0.001), cholesterol (+30%, p < 0.01,) and phospholipids levels (+58%, p < 0.001), whereas, triglycerides decreased (–28%, p < 0.001). These results showed that SMF effects on glucose and lipid metabolism are time-dependent.

General Physiology and Biophysics. Volume 29, 2010, No. 4: 390-395.

  Effect of thapsigargin on P-glycoprotein-negative and P-glycoprotein-positive L1210 mouse leukaemia cells
Mário Šereš 1), Peter Ditte, Albert Breier, Zdena Sulová

1)Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Vlárska 5, 833 34 Bratislava, Slovakia.

Expression of drug-transporting P-glycoprotein (P-gp, an integral protein of the plasma membrane) in neoplastic cells confers multidrug resistance and also involves alteration of cell sensitivity to inhibitors of the sarco/endoplasmic reticulum calcium pump thapsigargin (Th). Mouse leukaemia L1210 cell sublines that overexpress P-gp due to selection with vincristine (R) or stable transfection with a gene encoding human P-gp (T) were less sensitive to Th than the parental cell line (S). Th at a concentration of 0.1 μmol/l did not induce alterations in the amount of P-gp mRNA in R or T cells (S cells did not contain any measurable amount of this transcript as assessed by RT-PCR) or in the amount of calnexin (CNX) or glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in all three cell sublines. However, when using a concentration of 10 μmol/l, Th decreases the amounts of CNX, GAPDH (in S, R and T cells) and P-gp (in R and T cells) mRNAs. In contrast to R and T cells (which contain abundant P-gp), S cells did not contain any P-gp detectable by the c219 antibody on a Western blot. Th at a concentration of 0.1 μmol/l induced a reduction in the amount of P-gp present in R and T cells, particularly in isoforms with higher molecular weights (i.e., mature fully glycosylated isoforms). Similar results were observed when Th was used at a concentration of 10 μmol/l. R and T cells contained lower levels of CNX than S cells. While Th at a lower concentration did not alter the levels of CNX in S, R or T cells, a higher concentration of this substance induced a measurable decrease in the amount of CNX. S, R and T cells did not differ with respect to GAPDH content, but Th induced a reduction in the amount of this protein in all cell sublines. More pronounced results were observed when Th was applied at a concentration of 10 μmol/l comparing with a concentration of 0.1 mmol/l. These changes may be involved together with the Th efflux activity of P-gp in Th-resistance associated with the P-gp-mediated multidrug resistance of R and T cells.

General Physiology and Biophysics. Volume 29, 2010, No. 4: 396-401.

  The hypothesis of the main role of H2S in coupled sulphide-nitroso signalling pathway
Anna Bertova 1), Sona Cacanyiova, Frantisek Kristek, Olga Krizanova, Karol Ondrias, Zuzana Tomaskova

1)Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Vlarska 5, 833 34 Bratislava, Slovakia.

As a part of the nitroso signalling pathway, nitroso-compounds serve as stores and carriers of NO; as part of the sulphide signalling pathway, bound sulfane-sulphur compounds serve as stores and carriers of H2S. Here we hypothesise a coupled sulphide-nitroso signalling pathway, in which H2S plays a main role. H2S releases NO from the endogenous S-nitroso-compounds nitroso-cysteine, nitroso-acetylcysteine and nitroso-albumin. Relaxation of noradrenaline-precontracted aortic rings by H2S is also enhanced in the presence of nitroso-albumin, which may implicate the involvement of the nitroso signalling pathway. Pretreatment of albumin, cysteine, N-acetylcysteine and lipids with H2S results in binding of sulphur to these compounds creating thus new-modified sulphur compounds that release NO from nitroso-compounds directly and/or through released H2S, which suggests sulphide-nitroso signalling pathway participation. This hypothesis is supported by the observation that the pretreatment of noradrenaline-precontracted aortic rings with H2S significantly enhanced relaxation induced by nitroso-glutathione in the absence of H2S. We assume that the NO release from nitroso-compounds directly by H2S or indirectly by the H2S-induced sulphur-bound compounds represents coupled sulphide-nitroso signalling, which may explain some of the numerous biological effects of H2S that are shared with NO.

General Physiology and Biophysics. Volume 29, 2010, No. 4: 402-410.

  Thyroid non-Hodgkin's lymphoma expression pattern of nuclear retinoid and rexinoid receptor subtypes
Julius Brtko 1), Dana Macejova, Stefan Galbavy

1)Laboratory of Molecular Endocrinology, Institute of Experimental Endocrinology, Centre of Excellence Acknowledged by the European Commission, Slovak Academy of Sciences, Vlárska 3, 833 06 Bratislava, Slovakia.

General Physiology and Biophysics. Volume 29, 2010, No. 4: 411-413.

  Expressional changes of RyR1 and RyR2 in PC12 cells after induction of apoptosis
Dana Jurkovicova 1), Lubomira Lencesova, Olga Krizanova

1)Institute of Molecular Physiology and Genetics, Centre of Excellence for Cardiovascular Research, Slovak Academy of Sciences, Bratislava, Slovakia.

Ca2+ released from endoplasmic reticulum through ryanodine receptors (RyRs) and inositol 1,4,5-trisphosphate receptors (IP3Rs) can trigger apoptotic or necrotic pathways in cooperation with proapoptotic and/or prosurvival proteins, as those of Bcl-2 family. In such regulatory pathways expressional modulation of these Ca2+ transporters could also be expected. Therefore, our aim was to determine the expressional changes of RyR1 and RyR2 after experimental induction of apoptosis in PC12 cells. Our results showed significant decrease of RyR1 and RyR2 expressions, while caspase-3 and Bax expression significantly increased. We conclude that induction of apoptosis in PC12 cells could result in RyR expression down regulation.

General Physiology and Biophysics. Volume 29, 2010, No. 4: 414-418.

  Removal of the outermost arginine in IVS4 segment of the CaV3.1 channel affects amplitude but not voltage dependence of gating current
Mária Karmažínová 1), Ľubica Lacinová

1)Institute of Molecular Physiology and Genetics, Centre of Excellence for Cardiovascular Research, Slovak Academy of Sciences, Bratislava, Slovakia.

Positively charged amino acids in S4 segments of voltage-dependent CaV3.1 channel form putative voltage sensor. Previously we have shown that exchange of uppermost positively charged arginine in IVS4 segment for cysteine (mutation R1717C) affected deactivation and inactivation, but not activation of macroscopic current. Now we compared gating currents from both channels. Maximal amplitude of charge movement in R1717C channel decreased but voltage-dependent characteristics of charge movement were not significantly altered. We concluded that mutation of R1717C affects the coupling between S4 activation and pore opening, but not the S4 activation itself.

General Physiology and Biophysics. Volume 29, 2010, No. 4: 419-423.