Összesen 3 találat.


001-es BibID:BIBFORM049381
Első szerző:Bárdi Miklós
Cím:The effect of phenol derivatives on the sr Ca2+-atpase / Bardi M., Sarkozi S., Jona I.
Megjegyzések:During the contraction of a skeletal muscle fiber an action potential running along the fiber surface membrane results in the conformational change of the dihydropyridine receptors which in turn causes the opening of the sarcoplasmic reticulum (SR) calcium channels (RyR1). Calcium ions - released from the SR through the channels ? increase the myoplasmic calcium concentration that finally evokes the contraction of the fibre. The decrease in the myoplasmic calcium concentration causing relaxation of the fiber is achieved by the action of the SR Ca2+-ATPase (SERCA).It's known from the literature and our earlier results that thymol and its structural analogues ? which are widely used in the food, cosmetic and pharmaceutical industry as preservatives ? have influence on the activity of the RyR1 and SERCA. Continuing our previous work our aim was to study the effect of further phenol derivatives on the SERCA.Light SR (LSR) vesicles were prepared from rabbit skeletal muscle (m. longissimus dorsi) containing the SR Ca2+-pump in their membrane. ATP dependent hydrolytic activity of LSR vesicles was measured using "coupled enzyme assay" at 37oC. Specific activity of SERCA was calculated after determination of the non-specific activity in the presence of 20 ?M cyclopiazonic acid which specifically blocks SERCA.Pump activities were plotted against the concentration values of different drugs, dots were fitted by Hill-equation revealing the following parametes:4-Chloro-meta-crezol IC50=167 ? 8 ?M, nHill ~3;5-Chloro-orho-crezol IC50=554 ? 45 ?M, nHill ~2,4-Chloro-ortho-crezol IC50=1370 ? 88 ?M, nHill ~8.Almost all the compounds investigated here inhibited the pump except cresol which didn't exert any effect in concentration range 0?3 mM. Other compounds inhibited SERCA activity, but affinity and the number of ligands differed from each other.Our results prove that phenol derivative structural analogues have an inhibitory effect on SERCA activity but this effect is significantly modified by the relative position of the different substituent groups and the presence of cloride is also required for inhibition. The alterations in the shape of the pi electron cloud caused by the different substituents can be also involved in the effect of these compounds.Supported by: OTKA 81923
Tárgyszavak:Természettudományok Biológiai tudományok idézhető absztrakt
calcium release
calcium pump
Megjelenés:Acta Physiologica. - 205 : Suppl. 690 (2012), p. P1. -
További szerzők:Sárközi Sándor (1966-) (élettanász) Jóna István (1948-) (élettanász, fizikus)
Pályázati támogatás:81923
Internet cím:Szerző által megadott URL
Intézményi repozitóriumban (DEA) tárolt változat


001-es BibID:BIBFORM049380
Első szerző:Sárközi Sándor (élettanász)
Cím:Altered modulation of the skeletal type ryanodine receptor / calcium release channel by ATP in malignant hyperthermia / Sarkozi S., Lukacs B., Bardi M., Jona I.
Megjegyzések:We have shown previously that the activity of the Ryanodine Receptor / Calcium release channel (RyR/CRC) is modulated by ATP. Increasing ATP concentration results in an increase of open probability of the RyR/CRC and the dose response curve of the phenomena is biphasic having two distinctive activatory processes. The amplitude ratio of the two steps are 1:3 suggesting strong cooperation between the ATP binding sites and independent but cooperative binding of the ATP on the RyR1 monomers. It was also shown by several laboratories that mutations leading to malignant hyperthermia (MH) also increases the calcium sensitivity of the channel. Our aim was to test whether the ATP pharmacology is affected in MH and if this is the case in what way.Heavy SR vesicle was prepared as described previously using longissimus dorsi of a swine (Pietrin strain), which carries an MH causing homozygous arg615cysmutation. Following CHAPS+lipid solubilization, the functional RyR1 tetramer - the channel complex - was incorporated into a lipid bilayer. The bathing medium contained symmetrical 250 mM KCl ? 20mM PIPES ? pH:7.4. Free (ionized) calcium concentration was established using Ca-EGTA calcium buffer, calculated by Fabiato's method. Under voltage clamp conditions the channel current was recorded and the channel parameters were determined: such as open probability (Po), mean open time and specific conductance. The ATP pharmacology of the RyR/CRC was determined using 50 ?M Ca2+ free trans and 472 nM Ca2+ free cis, applying increasing Na2ATP concentration on the cis side.The mutant channel showed higher open probability compared to the wild type even in the absence of ATP. The mean open time was slightly higher in the mutant, but not significantly different from the wt. The ATP pharmacology of the mutant channel was different from the wt: the pronounced two phases disappeared from the ATP dependence of the open probability function. The increase of the open probability has two components: the mean open time increased significantly above 100 ?M, and the number of open events increased even more pronounced above 150 ?M ATP. The majority of the Po increase was attributed to the increase of the number of open events. All point histograms showed clearly two peaks without a trace of subconductance state: meaning that the synchrony of the four RyR1 monomers has not been changed due to the given mutation.Supported by: OTKA 81923
Tárgyszavak:Természettudományok Biológiai tudományok idézhető absztrakt
calcium release
Megjelenés:Acta Physiologica. - 205 : Suppl. 690 (2012), p. L9. -
További szerzők:Lukács Balázs (1978-) (élettanász) Bárdi Miklós Jóna István (1948-) (élettanász, fizikus)
Internet cím:Szerző által megadott URL
Intézményi repozitóriumban (DEA) tárolt változat


001-es BibID:BIBFORM086075
035-os BibID:(cikkazonosító)102213 (Scopus)85084348337 (WOS)000533610200001 (PubMed)32408025
Első szerző:Skaliczki Marianna
Cím:4-chloro-orto-cresol activates ryanodine receptor more selectively and potently than 4-chloro-meta-cresol / Mariann Skaliczki, Balázs Lukács, Zsuzsanna É. Magyar, Tünde Kovács, Miklós Bárdi, Szabolcs Novák, Gyula Diszházi, Sándor Sárközi, Ildikó Márton, Judit Péli-Szabó, István Jóna, Péter Nánási, János Almássy
Megjegyzések:In this study we performed the comprehensive pharmacological analysis of two stereoisomers of 4-chloro-meta-cresol (4CMC), a popular ryanodine receptor (RyR) agonist used in muscle research. Experiments investigating the Ca2+-releasing action of the isomers demonstrated that the most potent isomer was 4-chloro-orto-cresol (4COC) (EC50 = 55 ? 14 ?M), although 3-chloro-para-cresol (3CPC) was more effective, as it was able to induce higher magnitude of Ca2+ flux from isolated terminal cisterna vesicles. Nevertheless, 3CPC stimulated the hydrolytic activity of the sarcoplasmic reticulum ATP-ase (SERCA) with an EC50 of 91 ? 17 ?M, while 4COC affected SERCA only in the millimolar range (IC50 = 1370 ? 88 ?M). IC50 of 4CMC for SERCA pump was 167 ? 8 ?M, indicating that 4CMC is not a specific RyR agonist either, as it activated RyR in a similar concentration (EC50 = 121 ? 20 ?M). Our data suggest that the use of 4COC might be more beneficial than 4CMC in experiments, when Ca2+ release should be triggered through RyRs without influencing SERCA activity.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Skeletal muscle
Ryanodine receptor
Megjelenés:Cell Calcium. - 88 (2020), p. 102213. -
További szerzők:Lukács Balázs (1978-) (élettanász) Magyar Zsuzsanna Édua (1993-) (molekuláris biológus) Kovács Tünde (1990-) (biokémikus, molekuláris biológus) Bárdi Miklós Novák Szabolcs Diszházi Gyula (1992-) (gyógyszerész) Sárközi Sándor (1966-) (élettanász) Márton Ildikó (1954-) (fogszakorvos) Péli-Szabó Judit (1977-) (vegyész) Jóna István (1948-) (élettanász, fizikus) Nánási Péter Pál (1956-) (élettanász) Almássy János (1981-) (élettanász, biológus, angol-magyar szakfordító)
Pályázati támogatás:GINOP-2.3.2-152016-00040
Internet cím:Szerző által megadott URL
Intézményi repozitóriumban (DEA) tárolt változat
Rekordok letöltése1