JaLCDOI 10.18926/AMO/32289
FullText URL fulltext.pdf
Author Karatas, Yusuf| Ergun, Yusuf| Gocmen, Cemil| Secilmis, Ata| Singirik, Ergin| Dikmen, Atilla| Bayasal, Firuz|
Abstract <p>The present study was undertaken to investigate the postsynaptic effects of aminoglycosides on contractions evoked by acetylcholine (ACh), KCl, electrical field stimulation (EFS) and Na(+)- and Ca(2+)-free Ringer solution with 0.2 mM Na2 EDTA (NaFCaFR) in the isolated frog rectus abdominis. Neomycin inhibited contraction elicited by ACh, NaFCaFR, and EFS at the higher frequencies (8 and 10 Hz) but not those elicited by KCl and EFS at the lower frequencies (2, 3 and 5 Hz). D-tubocurarine inhibited ACh-induced contractions in a concentration-dependent manner. In addition, drug reduced EFS-evoked contractions to a limited extent. Lower concentrations (10(-5), 5 x 10(-5), 10(-4), 2 x 10(-4) and 3 x 10(-4) M) but not higher concentrations (4 x 10(-4) and 5 x 10(-4) M) of methoxyverapamil exhibited a concentration-dependent inhibitory action on NaFCaFR-induced contractions. Similar inhibitions of the same type of contraction were displayed by aminoglycosides (neomycin, streptomycin, netilmycin, gentamycin and amikacin). These results suggest that in addition to their antagonistic action on nicotinic receptors in the frog rectus abdominis, aminoglycosides may exert stabilizing effects on some functional components contributing to contractions at the membrane.</p>
Keywords aminoglycoside voltage sensor sodium and calcium free Ringer solution frog rectus abdominis contoraction
Amo Type Article
Published Date 2000-04
Publication Title Acta Medica Okayama
Volume volume54
Issue issue2
Publisher Okayama University Medical School
Start Page 49
End Page 56
ISSN 0386-300X
NCID AA00508441
Content Type Journal Article
language 英語
File Version publisher
Refereed True
PubMed ID 10806525
Web of Sience KeyUT 000086735900001
JaLCDOI 10.18926/AMO/32273
FullText URL fulltext.pdf
Author Ucar, Peyman| Gocmen, Cemil| Secilmis, Ata| Karatas, Yusuf| Singirik, Ergin| Onder, Serpil| Dikmen, Atilla| Baysal, Firuz|
Abstract <p>The applications of ultraviolet (UV) light (336 nm) on the upper oesophageal strips of frog elicited relaxant responses in the presence of NaNO2 (50 microM). The tissues were mounted under the tension 0.5 g in an organ bath containing Ringer solution, maintained at 25 degrees C and gassed with 100% O2. The responses were recorded on a kymograph via an isotonic lever. Antimegaloblastic agents, including hydroxocobalamin (1, 10, and 100 microM), cyanocobalamin (1, 10, 25, and 100 microM), and folic acid (1, 10, 50, 100, and 200 microM), significantly attenuated the relaxation response to UV light. Folinic acid (1, 10, 25, and 100 microM), however, enhanced the relaxation. Pyrogallol (50 microM), hydroquinone (50 microM), and diethyldithiocarbamic acid (8 mM) were found ineffective for attenuation, though FeSO4 (200, 400, and 500 microM) and hemoglobin (50 microM), respectively, exerted significant inhibition. L-arginine methylester (500 microM) did not impair UV-induced relaxation. Based on these results, we concluded that a mechanism involving undefined action(s) of antimegaloblastic drugs may cause alterations in the UV light-induced relaxation of the tissue used.</p>
Keywords ultraviolet light frog oesophageal strip hydroxocobalamin cyanocobalamin folic acid
Amo Type Article
Published Date 2000-08
Publication Title Acta Medica Okayama
Volume volume54
Issue issue4
Publisher Okayama University Medical School
Start Page 147
End Page 152
ISSN 0386-300X
NCID AA00508441
Content Type Journal Article
language 英語
File Version publisher
Refereed True
PubMed ID 10985174
Web of Sience KeyUT 000089132800002
JaLCDOI 10.18926/AMO/31632
FullText URL fulltext.pdf
Author Buyukafsar, Kansu| Gocmen, Cemil| Secilmis, Ata| Karatas, Yusuf| Gokturk, Sinem| Kalyoncu, Nuri Ihsan|
Abstract <p>The effects of thimerosal, a sulfhydryl oxidizing agent on nitrergic, endothelium-dependent and -independent relaxations were investigated to examine the possibility that the nitrergic neurotransmitter and endothelium-derived relaxing factor (EDRF) could be S-nitrosothiol or free nitric oxide (NO) in the isolated mouse corpus cavernosum. Thimerosal (5 x 10(-6)-2 x 10(-5) M) inhibited or almost abolished electrical field stimulation--(EFS, 30V, 0.5 ms, 15 sec, 1, 2, 4, 8, 16 Hz), acetylcholine--(ACh, 5 x 10(-8)-1.25 x 10(-6) M), glyceryl trinitrate--(GTN, 3 x 10(-7)-3 x 10(-6) M), and S-nitrosoglutathione--(GSNO, 5 x 10(-6)-1.25 x 10(-4) M) induced relaxations. Thiomerosal inhibition seems to be specific to L-arginine NO pathways since it had no effect on acidified sodium nitrite--(10(-4)-5 x 10(-4) M), photoactivated sodium nitrite--(2 x 10(-4) M), isoprenaline--(10(-6) M), or papaverine--(10(-4) M) elicited relaxations. Moreover, the inhibitory effect of thimerosal on the nitrergic, ACh- or GTN-induced relaxations were partly reversed by sulfhydryl-containing compounds, L-cysteine (10(-3) M), dithiothreitol (10(-3) M), or glutathione (10(-3) M). However L-methionine (10(-3) M), which contains a methyl group on the sulphur atom, failed to restore the thimerosal inhibition. Thimerosal did not change the contraction produced by 10(-4) M NG-nitro-L-arginine methyl ester. These findings indicate that the nitrergic neurotransmitter as well as EDRF may not be free NO but NO-transferring molecules, probably S-nitrosothiols, in the mouse corpus cavernosum.</p>
Keywords nitric oxide endothelium-derived relaxing factor nitrergic neurotransmitter thimerosal corpus cavernosum S-nitrosothiols
Amo Type Article
Published Date 1999-10
Publication Title Acta Medica Okayama
Volume volume53
Issue issue5
Publisher Okayama University Medical School
Start Page 209
End Page 215
ISSN 0386-300X
NCID AA00508441
Content Type Journal Article
language 英語
File Version publisher
Refereed True
PubMed ID 10561729
Web of Sience KeyUT 000083427100002
JaLCDOI 10.18926/AMO/31613
FullText URL fulltext.pdf
Author Secilmis, Ata| Ocal, Isil| Gocmen, Cemil| Dikmen, Atilla| Singirik, Ergin| Onder, Serpil| Baysal, Firuz|
Abstract <p>In the present study, we aimed to obtain further evidence in favour of the hypothesis that nitric oxide (NO) is a major mediator of endothelium-dependent vasorelaxation and to clarify whether NO plays a role in papaverine-induced vasorelaxation. The relaxant effects of acetylcholine (Ach), acidified NaNO2 or papaverine were investigated on isolated helical strips of the rat thoracic aorta precontracted with phenylephrine in an organ bath containing Krebs solution aerated with 95% O2 and 5% CO2. The relaxation was quantified as % peak reduction of phenylephrine contracture. Saponin abolished the relaxant effects of Ach completely whereas it had no effect on the responses to acidified NaNO2 or papaverine. NG-nitro-L-arginine (L-NOARG) reduced the effects of Ach significantly, but it was ineffective on the relaxation induced by acidified NaNO2. The inhibitory action of L-NOARG was partly restored by L-arginine, but not by D-arginine. Hemoglobin, hydroxocobalamin and hydroquinone exhibited significant inhibition on the relaxation evoked by Ach and acidified NaNO2. L-NOARG, hydroxocobalamin and hydroquinone caused only limited but significant decrease in the relaxation due to papaverine. This phenomenon was also observed by increasing phenylephrine concentration leading to an enhancement in the contraction. Our findings strongly support the view that Ach-induced relaxation of rat aorta strips is mediated by free NO released from the endothelium and the results suggest that NO may indirectly contribute to papaverine-induced relaxation.</p>
Keywords rat aorta helical strips nitric oxide papaverine hydroxocobalamin hydroquinone
Amo Type Article
Published Date 1999-08
Publication Title Acta Medica Okayama
Volume volume53
Issue issue4
Publisher Okayama University Medical School
Start Page 171
End Page 177
ISSN 0386-300X
NCID AA00508441
Content Type Journal Article
language 英語
File Version publisher
Refereed True
PubMed ID 10488403
Web of Sience KeyUT 000082334300002
JaLCDOI 10.18926/AMO/30799
FullText URL fulltext.pdf
Author Secilmis, Ata| Atci, Serare| Yaktubay, Naciye| Karatas, Yusuf| Gocmen, Cemil| Singirik, Ergin| Dikmen, Atilla| Baysal, Firuz|
Abstract <p>&#8195;The aim of the study was to investigate whether Na<sup>+</sup> channels play a role in the twitch component of the response of the isolated frog rectus abdominis to Ca<sup>2+</sup>-free Ringer solution with 0.2 mM Na<sub>2</sub>EDTA by using tetrodotoxin and some other well known drugs that exhibit a blocking action on Na<sup>+</sup> channels. In the presence of 5 x 10<sup>-7</sup> M tetrodotoxin, the twitch component, measured isotonically, disappeared. Although 10<sup>-7</sup> M d-tubocurarine was found to be ineffective, a complete blockage of twitch amplitude was observed at 5 x 10<sup>-6</sup> M concentration of the drug. The inhibitory action of d-tubocurarine on twitch response was not antagonized by 10<sup>-6</sup> and 10<sup>-5</sup> M carbachol. Propranolol (10<sup>-6</sup> - 10<sup>-5</sup> M), lidocaine (2 x 10<sup>-6</sup> - 10<sup>-5</sup> M), quinine (10<sup>-6</sup> - 2 x 10<sup>-5</sup> M) and quinidine (10<sup>-6</sup> - 2 x 10<sup>-5</sup> M) inhibited maximal twitch amplitude in a concentration dependent manner. These findings strongly suggest that activation of tetrodotoxin sensitive Na<sup>+</sup> channel may play a primary role at twitch generation during exposure of the frog rectus abdominis to Ca<sup>2+</sup>-free Ringer solution with Na<sub>2</sub> EDTA.</p>
Keywords tetrodotoxin Ca<sup>2+</sup>-free medium with Na<sub>2</sub> EDTA isolated frog rectus abdominis Na<sup>+</sup> channel blocking activity
Amo Type Article
Published Date 1997-06
Publication Title Acta Medica Okayama
Volume volume51
Issue issue3
Publisher Okayama University Medical School
Start Page 115
End Page 120
ISSN 0386-300X
NCID AA00508441
Content Type Journal Article
language 英語
File Version publisher
Refereed True
PubMed ID 9227789
Web of Sience KeyUT A1997XJ12700001