5 research outputs found
Da li holesterol vezan za hemoglobin utiče na anti-oksidativni enzimski sistem u humanim eritrocitima?
In a previous study, it was shown that the lipid fraction, which is occasionally observed in red blood cell hemolysates, represents cholesterol (Ch) associated with phospholipid firmly bound to haemoglobin (termed Hb-Ch). The current study was conducted to investigate whether Hb-Ch could affect the primary anti-oxidant enzyme defence system in human erythrocytes. Sixty healthy volunteers were used for the current study. Group 1 consisted of 28 subjects without or with a low level of Hb-Ch. Group 2 comprised 32 subjects with a considerably higher level of Hb-Ch. The activities of erythrocyte superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase, as well as the content of methaemoglobin (metHb) were measured in both groups. The results indicated that the amount of Hb-Ch neither influenced the activities of the erythrocyte anti-oxidant enzymes nor altered the level of metHb. However, a higher amount of Hb-Ch changed the correlations in the part of the anti-oxidant defence system relating to glutathione, suggesting increased peroxidative pressure from plasma lipids. Group 2 also had significantly increased concentrations of total plasma Ch and triglycerides. Together, these facts are strong indications that the anti-oxidant defence system in human erythrocytes finely retunes its composition according to plasma oxidative demands.U prethodnom radu pokazano je da lipidna frakcija koja se javlja u hemolizatu zdravih ljudi predstavlja holesterol (asosovan sa fosfolipidima) čvrsto vezan za hemoglobin (Hb-Ch). U ovom radu ispitivan je uticaj Hb-Ch na anti-oksidativni enzimski sistem u humanim eritrocitima. Određena je aktivnost superoksid-dizmutaze, katalaze, glutation-peroksidaze i glutation-reduktaze, kao i sadržaj met-hemoglobina (metHb) u eritrocitima 60 ljudi, podeljenih u dve grupe na osnovu količine Hb-Ch. Rezultati pokazuju da količina prisutnog Hb-Ch ne menja aktivnost merenih enzima, niti nivo metHb. Međutim, u grupi ispitanika sa povećanim sadržajem Hb-Ch zapažene su korelativne promene u delu anti-oksidativnog enzimskog sistema povezanog sa glutationom. U istoj grupi detektovane su i veće koncentracije ukupnog holesterola i triglicerida u plazmi, što zajedno ukazuje na povećani peroksidativni pritisak iz plazme. Ovi rezultati ukazuju da odbrambeni anti-oksidativni enzimski sistem u humanim eritrocitima prilagođava svoju organizaciju prema zahtevima iz svog okruženja.
Chloride channels mediate sodium sulphide-induced relaxation in rat uteri
Background and PurposeHydrogen sulphide reduces uterine contractility
and is of potential interest as a treatment for uterine disorders. The
aim of this study was to explore the mechanism of sodium sulphide
(Na2S)-induced relaxation of rat uterus, investigate the importance of
redox effects and ion channel-mediated mechanisms, and any interactions
between these two mechanisms.
Experimental ApproachOrgan bath studies were employed to assess the
pharmacological effects of Na2S in uterine strips by exposing them to
Na2S with or without Cl- channel blockers (DIDS, NFA, IAA-94,
T16Ainh-A01, TA), raised KCl (15 and 75mM), K+ channel inhibitors
(glibenclamide, TEA, 4-AP), L-type Ca2+ channel activator (S-Bay K
8644), propranolol and methylene blue. The activities of antioxidant
enzymes were measured in homogenates of treated uteri. The expression of
bestrophin channel 1 (BEST-1) was determined by Western blotting and
RT-PCR.
Key ResultsNa(2)S caused concentration-dependent reversible relaxation
of spontaneously active and calcium-treated uteri, affecting both
amplitude and frequency of contractions. Uteri exposed to 75mM KCl were
less sensitive to Na2S compared with uteri in 15mM KCl. Na2S-induced
relaxations were abolished by DIDS, but unaffected by other modulators
or by the absence of extracellular HCO3-, suggesting the involvement of
chloride ion channels. Na2S in combination with different modulators
provoked specific changes in the anti-oxidant profiles of uteri. The
expression of BEST-1, both mRNA and protein, was demonstrated in rat
uteri.
Conclusions and ImplicationsThe relaxant effects of Na2S in rat uteri
are mediated mainly via a DIDS-sensitive Cl--pathway. Components of the
relaxation are redox- and Ca2+-dependent
Does cholesterol bound to haemoglobin affect the anti-oxidant enzyme defence system in human erythrocytes?
In a previous study, it was shown that the lipid fraction, which is occasionally observed in red blood cell hemolysates, represents cholesterol (Ch) associated with phospholipid firmly bound to haemoglobin (termed Hb-Ch). The current study was conducted to investigate whether Hb-Ch could affect the primary anti-oxidant enzyme defence system in human erythrocytes. Sixty healthy volunteers were used for the current study. Group 1 consisted of 28 subjects without or with a low level of Hb-Ch. Group 2 comprised 32 subjects with a considerably higher level of Hb-Ch. The activities of erythrocyte superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase, as well as the content of methaemoglobin (metHb) were measured in both groups. The results indicated that the amount ofHb-Ch neither influenced the activities of the erythrocyte anti-oxidant enzymes nor altered the level of metHb. However, a higher amount ofHb-Ch changed the correlations in the part of the anti-oxidant defence system relating to glutathione, suggesting increased peroxidative pressure from plasma lipids. Group 2 also had significantly increased concentrations of total plasma Ch and triglycerides. Together, these facts are strong indications that the anti-oxidant defence system in human erythrocytes finely retunes its composition according to plasma oxidative demands
Reversible Oxidation of Myometrial Voltage-Gated Potassium Channels with Hydrogen Peroxide
The uteri, spontaneously active or Ca2+ (6 mM) induced, were allowed to equilibrate, and to inhibit voltage-gated potassium () channels 1 mM 4-amino pyridine (4-AP) was applied for 15 min before adding H2O2 . H2O2 was added cumulatively: 2 μM, 20 μM, 200 μM, 400 μM, and 3 mM. Average time for H2O2 concentrations (2, 20, 200, and 400) μM to reach its full effect was 15 min. H2O2 3 mM had a prolonged effect and therefore was left to act for 30 min. Two-way ANOVA showed significant differences in time dependency between spontaneous and Ca2+-induced rat uteri after applying 3 mM H2O2 (type of contraction, ), but not 400 μM H2O2 (). Our results indicate that H2O2 oxidises channel intracellular thiol groups and activates the channel, inducing relaxation. Cell antioxidative defence system quickly activates glutathione peroxidase (GSHPx) defence mechanism but not catalase (CAT) defence mechanism. Intracellular redox mechanisms repair the oxidised sites and again establish deactivation of channels, recuperating contractility. In conclusion, our results demonstrate that channels can be altered in a time-dependent manner by reversible redox-dependent intracellular alterations
The effects of wild-type and mutant SOD1 on smooth muscle contraction
In this work we compared the mutated liver copper zinc-containing superoxide dismutase (SOD1) protein G93A of the transgenic rat model of familial amyotrophic lateral sclerosis (FALS), to wild-type (WT) rat SOD1. We examined their enzymatic activities and effects on isometric contractions of uteri of healthy virgin rats. G93A SOD1 showed a slightly higher activity than WT SOD1 and, in contrast to WT SOD1, G93A SOD1 did not induce smooth muscle relaxation. This result indicates that effects on smooth muscles are not related to SOD1 enzyme activity and suggest that heterodimers of G93A SOD1 form an ion-conducting pore that diminishes the relaxatory effects of SOD1. We propose that this type of pathogenic feedback affects neurons in FALS