Ubururu bwa metilene na okiside ya azote: NOS, cGMP, n'ubutumwa mu miyoboro y'amaraso

Ikibazo gisa n'icyoroshye: ese ubururu bwa metilene buhagarika okiside ya azote? Muri laboratwari, igisubizo kigabanyijemo ibibazo bine bitandukanye, kandi buri kimwe kigira igerageza ryacyo. Kubyitiranya ni yo mpamvu nyamukuru ituma inyandiko ku bururu bwa metilene na okiside ya azote zisa n'izivuga ibintu byemejwe ariko zidasobanutse.

Tekereza ku butumwa bwa okiside ya azote nk'urunigi rugizwe n'ibice bine. Gene yandukurwa kugira ngo hakorwe enzime yitwa nitric oxide synthase. Iyo enzime ihindura arijinine ikayigira okiside ya azote. Iyo gazi ikwirakwira ikagera aho igenewe mbere yo kwitwara hamwe n'ikindi kintu. Enzime ishonga yitwa guanylate cyclase irayumva maze igakora GMP y'umuzenguruko. Ingaruka z'ubururu bwa metilene kuri buri gice zaratangajwe, ariko ibimenyetso byavuye ku byitegererezo byateguwe mu buryo butandukanye, ku bwibande butandukanye, no ku bwoko butandukanye bwa enzime. Icyabonetse ku gice kimwe ntigihamya igikorwa ku kindi.

Urukurikirane rusanzwe, rusobanuwe mu buryo bworoshye

Mu rukuta rw'umuyoboro w'amaraso, urukurikirane rusanzwe rugenda rutya. Ikintu gitera igisubizo kigira icyo gikora ku ngirabuzimafatizo y'urwugara rw'imbere rw'umuyoboro w'amaraso. Nitric oxide synthase yo muri izo ngirabuzimafatizo, yitwa eNOS cyangwa NOS3, ikora okiside ya azote nke mu gihe gito. Iyo gazi ikwirakwira ikinjira mu ngirabuzimafatizo y'umukaya woroshye iri hafi, ikifatanya na heme ifite icyuma kiri mu mimerere yagabanyijwe ya guanylate cyclase ishonga, maze ikihutisha ihindurwa rya GTP ikaba GMP y'umuzenguruko. GMP y'umuzenguruko ikangura protein kinase G, uburyo kalisiyumu igenzurwa burahinduka, maze umukaya ukaruhuka.

Hari urundi rukurikirane rukwiye gutandukanywa n'urwo. Mu gihe cy'ubwandu cyangwa igihe ingirabuzimafatizo zihuye na sitokine, zandukura amakuru akora indi enzime: nitric oxide synthase ikorwa nyuma yo gukangurwa, cyangwa iNOS, initwa NOS2. Ikora okiside ya azote nyinshi kandi mu gihe kirekire kurusha eNOS. Ubwoko bwa gatatu, NOS yo mu ngirabuzimafatizo z'imyakura cyangwa nNOS, bukoreshwa mu rundi rwego. Iyo inyandiko ivuze nitric oxide synthase itagaragaje ubwoko bwayo, banza urebe ubwo bapimye. Incamake y'uburyo ubururu bwa metilene bwimura elegitoroni na yo ivuga kimwe ku byo bwibasira mu bikorwa byo gutakaza no kwakira elegitoroni muri rusange: icyo giherekanya elegitoroni nta cyo gikora cyonyine, kandi uwo gikorana na we kuri buri mpera ni we ugena ibivamo.

GMP y'umuzenguruko yapimwe na yo ni igipimo gikubiyemo ingaruka z'ibikorwa byinshi, si igerageza ripima enzime ku buryo butaziguye. Ingano yayo igaragaza iyakozwe na cyclase ukuyemo iyashenywe na phosphodiesterases, cyane cyane PDE5 mu mikaya yoroshye y'imiyoboro y'amaraso. Bityo, kugabanuka kwa GMP y'umuzenguruko bivuga ko ubutumwa buke ari bwo bwageze ku bwakira. Ibyo byonyine ntibigaragaza igice cyahagaritse gukora.

Igice 1: hakorwa enzime iNOS nke

Mu ngirabuzimafatizo za macrophage z'imbeba nto zakanguriwe na lipopolysaccharide ya bagiteri, interferon gamma, cyangwa byombi, ubururu bwa metilene bwabujije izamuka ryari ryitezwe rya poroteyine iNOS kandi bugabanya cyane RNA itwara amakuru ya iNOS mu magerageza yo kwandukura amakuru muri macrophage. Ikintu gitanga amakuru y'ingenzi ni icyagumye uko cyari kiri. Isenywa ry'ikumira ryitwa I kappa B alpha, iyongerwa ry'amatsinda ya fosifate kuri NF kappa B na STAT1, n'ukwimuka kw'ibyo bintu byinjira mu ntima y'ingirabuzimafatizo byakomeje ahanini uko byari bisanzwe. Icyagabanutse ni ukwifatanya kwabyo na DNA, byemejwe n'igerageza rya chromatin immunoprecipitation ryagaragaje ko byari bike ku gace gatangiza iyandukurwa rya iNOS.

Iyo ni ingaruka ku igenzura rya gene ibanziriza ingano ya enzime ikorwa, si ihagarikwa ryihuse rya enzime isanzwe ihari. Irebana n'ubutumwa bwo mu gihe cy'ububyimbirwe, aho ibintu bigenzura iyandukurwa bigomba kwifatanya n'agace kabutangira mbere y'uko poroteyine iboneka. Nta cyo ivuga ku buryo butaziguye kuri eNOS isanzwe iri mu muyoboro w'amaraso utarakangurwa, kandi ni muri urwo rwego ikwiye gusobanurwa.

Igice 2: enzime NOS isanzwe ihari ikora buhoro

Ubushakashatsi ku mbeba nini bwagerageje urundi rwego. Imbeba nini z'ingabo zitari zasinzirijwe zatewe lipopolysaccharide mu mutsi, nyuma y'amasaha atatu ziterwa umuti w'amazi arimo umunyu cyangwa ubururu bwa metilene ku rugero rwa 3 mg per kg mu mutsi. Igikorwa cya nitric oxide synthase mu gice cyo hagati cyo hasi cya hypothalamus cyapimwe hakoreshejwe ihindurwa rya arijinine yashyizweho ikimenyetso ikaba sitiruline mu bushakashatsi ku gikorwa cya NOS muri hypothalamus. Guhangayika hamwe n'amazi arimo umunyu byonyine byatumye habaho igikorwa runaka kitagendera kuri kalisiyumu, kandi lipopolysaccharide yacyongereye kigera hafi ku nshuro icumi igipimo cy'itsinda ryagereranywagaho. Ubururu bwa metilene bwakuyeho ibyo bikorwa byombi byari byatewe. Igikorwa gisanzwe kigendera kuri kalisiyumu nticyahindutse muri icyo gice cy'umubiri, kuri urwo rugero no muri icyo gihe cyo gupima.

Soma icyo gisubizo uko cyanditswe: igikorwa cyapimwe cyo mu bwoko bwa iNOS cyaragabanutse muri ibyo bihe. Ntabwo ari igipimo cy'ikorwa rishingiye kuri gene, kandi ntigihamya ko ubururu bwa metilene buri gihe bwibasira iNOS aho kwibasira eNOS cyangwa nNOS. Ubushakashatsi kuri enzime yatunganyijwe igatandukanywa n'ibindi burushaho kugaragaza impamvu yo kwitonda. Mu magerageza apima nitric oxide synthase yatunganyijwe ku buryo butaziguye, ubururu bwa metilene bwahagaritse burundu ikorwa rya sitiruline kuri 30 micromolar. Ubwibande bwagabanyije igikorwa ho kimwe cya kabiri bwari hafi ya 5.3 micromolar hatarimo superoxide dismutase na 9.2 micromolar iyo yari irimo, nk'uko byatangajwe mu igereranya rya NOS yatunganyijwe na guanylate cyclase. Ubundi bushakashatsi kuri nNOS yatunganyijwe bwagaragaje uruhare rwo gutakaza elegitoroni kwa heme yifatanyije na enzime. Isomo ry'ingenzi ni uko ihagarikwa rya NOS ku buryo butaziguye ribaho koko muri sisitemu zatandukanyijwe n'ibindi, ariko igisubizo cyo muri hypothalamus ntigishobora gukoreshwa mu kwemeza muri rusange ko ubururu bwa metilene butagira icyo bukora kuri NOS zose zisanzwe zihari, ahantu hose.

Igice 3: okiside ya azote iratakara mbere yo kuhagera

Ikimenyetso gisobanutse kurusha ibindi cy'uko ikindi kintu kitari uguhagarika enzime gishobora gusobanura igabanuka rya GMP y'umuzenguruko cyavuye mu ngirabuzimafatizo z'imikaya yoroshye y'imitsi ijyana amaraso mu bihaha by'urukwavu, zahinzwe muri laboratwari. Igerageza ryasimbutse burundu NOS ikorerwa mu ngirabuzimafatizo, ryongeramo ku buryo butaziguye ibintu bitanga okiside ya azote, hanyuma rireba niba ubururu bwa metilene bwari bugikomeza kugabanya igisubizo cya GMP y'umuzenguruko mu bushakashatsi kuri superokiside mu mikaya yoroshye y'imiyoboro y'amaraso.

Ibintu bitatu bitanga okiside ya azote byageragejwe ku bwibande kuva kuri 1 kugeza kuri 100 micromolar: S nitroso L cysteine, sodium nitroprusside, n'ikinyabutabire gisa na byo, gihamye kandi cyakuweho itsinda rya amine, cyitwa MPANO. Byose byongereye GMP y'umuzenguruko kuva hafi ku nshuro 1.5 kugeza ku nshuro 12. Ubururu bwa metilene kuri 10 micromolar bwagabanyije igisubizo cy'ibintu bibiri bya mbere kuva kuri 51 kugeza kuri 100 ku ijana, ariko ntibwahindura igisubizo cya MPANO. Iyo ubururu bwa metilene buza kuba buhagarika gusa ahabera igikorwa cya cyclase, byari kugorana gusobanura impamvu bwatandukanyaga ibyo bitanga okiside ya azote, kuko byose bigana kuri enzime imwe ikora nyuma yabyo.

Hanyuma ibigereranyo bitatu byerekanye ko uburyo bwabiteye bwari bushingiye kuri superokiside. Icya mbere, gukora superokiside hanze y'ingirabuzimafatizo hakoreshejwe xanthine hamwe na xanthine oxidase byatanze ishusho imwe: igisubizo cya CYSNO na nitroprusside cyarahagaritswe, icya MPANO nticyahinduka. Icya kabiri, ubururu bwa metilene bwatumye ingirabuzimafatizo z'imikaya yoroshye zikora superokiside yiyongeraga bitewe n'ingano yakoreshejwe n'igihe, yapimwe hakurikijwe kwakira elegitoroni kwa cytochrome c. Icya gatatu, superoxide dismutase yabujije burundu iryo hagarikwa, ariko catalase ntiyabikora. Ibyo byerekana ko muri icyo cyitegererezo superokiside, aho kuba hydrogen peroxide, ari yo yagize uruhare rwa hafi.

Birakwiye kuvuga uko iryo gerageza ryakozwe igihe ubwoko bubiri bw'ingirabuzimafatizo bwahingwaga hamwe, kuko ryerekana aho ingaruka zabereye. Ingirabuzimafatizo z'urwugara rw'imbere rw'imiyoboro y'amaraso zari ku turahure duto zihingwa igihe gito hamwe n'ingirabuzimafatizo z'imikaya yoroshye. Bityo, ikintu zarekura mu buryo busanzwe cyongereye GMP y'umuzenguruko mu mikaya yoroshye kuva ku nshuro eshatu kugeza ku munani. Kubanza gushyira ubururu bwa metilene kuri rumwe muri izo nzego byagabanyije ubwo butumwa, kandi superoxide dismutase yagaruye igice cy'ubutumwa bwari bwagabanutse igihe ubururu bwa metilene bwari bwabanje gushyirwa ku ngirabuzimafatizo z'urwugara rw'imbere. Mu yandi magambo, ubururu bwa metilene si ngombwa ko bukorera imbere mu ngirabuzimafatizo y'umukaya woroshye yakira ubutumwa. Bushobora kugabanya ubutumwa bukuraho ubutwara igihe bukiri mu nzira. Amabwiriza yo gusoma ubushakashatsi ku bururu bwa metilene afata ibi nk'ihame rusange: vuga urwego igikorwa cyakorewemo mbere yo kuvuga molekile cyibasiye.

Kwita ibi ihagarikwa rya NOS byaba ari amakosa. Ibyo bitanga okiside ya azote ntibyakeneye intambwe ya synthase kugira ngo bikore, nyamara ubutumwa bwaragabanutse.

Igice 4: icyakira ubutumwa ubwacyo kigira igisubizo gito

Ingaruka zitaziguye kuri guanylate cyclase ishonga zirahari, ariko ubwibande ni ingenzi. Mu igereranya rya enzime zatunganyijwe ryavuzwe haruguru, cyclase yakanguriwe na okiside ya azote yasabaga ubururu bwa metilene bugera hafi kuri 60 micromolar kugira ngo igikorwa cyayo kigabanuke ho kimwe cya kabiri, mu gihe kuri NOS byabaga hafi ya 5 kugeza kuri 9 micromolar. Ndetse na 1 millimolar yatanze ihagarikwa ry'igice gusa, nubwo ari ryo rinini ryabonetse. Iryo tandukaniro ringana hafi n'inshuro esheshatu kugeza kuri cumi n'imwe. Bityo, igerageza ku ngirabuzimafatizo rikoresha ubwibande buke bwo ku rwego rwa micromolar rigatuma GMP y'umuzenguruko igabanuka ntirishobora kwitwa ihagarikwa ryibasira cyclase gusa hashingiwe ku gipimo cya GMP y'umuzenguruko cyonyine.

Ubushakashatsi bwakurikiyeho ku gutakaza no kwakira elegitoroni bwatanze indi mpamvu yo kwitonda: ubururu bwa metilene bwahagaritse igikorwa cya cyclase yari yakanguriwe na okiside ya azote hakoreshejwe uburyo butandukanye no gutakaza elegitoroni bisanzwe kw'icyuma cya heme bitewe n'umwuka. Bityo, icyakira ubutumwa gishobora kubangamirwa, ariko uburyo bw'imikoranire y'ibinyabutabire ntiburamenyekana neza. Kandi iryo tandukaniro ry'ubwibande risobanura ko, igihe hakoreshejwe ubwibande buke bwo ku rwego rwa micromolar, hakwiye kubanza kugenzurwa niba ingaruka za superokiside na NOS atari zo zabiteye. Aha ni na ho kugenzura phosphodiesterase bifite umwanya. Keretse isenywa ryarapimwe cyangwa rigahagarikwa, kugabanuka kw'ukwirundanya kwa GMP y'umuzenguruko gushobora gusobanurwa n'ikorwa rito, isenywa ryihuse, cyangwa byombi.

Impamvu ibi bidashobora guhurizwa mu mvugo imwe ku muvuduko w'amaraso

Buri gice cyagaragajwe muri sisitemu itandukanye. Iyandukurwa ry'amakuru muri macrophage si igikorwa cya enzime muri hypothalamus. Igikorwa cyo muri hypothalamus nyuma ya lipopolysaccharide si umurego usanzwe w'urwugara rw'imbere rw'imiyoboro y'amaraso. Ikintu kirekurwa mu buryo busanzwe n'ingirabuzimafatizo z'urwo rwugara zihingwa hamwe n'izindi si ukwaguka kw'imiyoboro y'amaraso guterwa n'ikinyabutabire gikangura icyakira. Ingirabuzimafatizo z'imitsi ijyana amaraso mu bihaha zihinzwe muri laboratwari kandi zikageragezwaho ubururu bwa metilene kuri 10 micromolar si urwungano rw'itembera ry'amaraso rw'umuntu. Kubihuriza mu mvugo nk'ivuga ko ubururu bwa metilene bwongera umuvuduko w'amaraso buhagarika okiside ya azote bikuraho neza neza itandukaniro ibigereranyo byari byarashyiriweho kubungabunga.

Ibigenzurwa bitatu bituma ibisobanuro bitarenga ibimenyetso. Icya mbere, vuga ubwoko bwa enzime: eNOS ku murego usanzwe w'imiyoboro y'amaraso, iNOS ku ikorwa rya okiside ya azote ryatewe n'ububyimbirwe, nNOS ku bijyanye n'imyakura no mu magerageza amwe akoresha enzime zatunganyijwe. Icya kabiri, vuga uburyo ubutumwa bwa okiside ya azote butangwa: ikorwa ryayo imbere mu ngirabuzimafatizo, irekurwa risanzwe n'ingirabuzimafatizo z'urwugara rw'imbere, cyangwa ikintu runaka kiyitanga nka CYSNO, nitroprusside, cyangwa MPANO, kuko ikiyitanga gihamye kitabangamiwe n'ubururu bwa metilene mu gihe ibidahamye byabangamiwe. Icya gatatu, vuga ubwibande n'icyagaruye igisubizo: kugarura igisubizo hakoreshejwe superoxide dismutase byerekana uruhare rwa superokiside; kutabishobora kwa catalase bitanga impamvu yo kutitirira hydrogen peroxide ingaruka muri icyo cyitegererezo; kwigana ingaruka hakoreshejwe xanthine oxidase byerekana ko ubwo buryo bwonyine buhagije; naho amagerageza kuri enzime zatunganyijwe atandukanya ingaruka zitaziguye ku gikorwa cya enzime n'itakara ry'ubutumwa mu nzira.

Incamake ni iyi. Ubururu bwa metilene bukwiye gufatwa nk'ikintu kibangamira ahantu henshi urukurikirane rw'ubutumwa ruva kuri okiside ya azote rukagera kuri GMP y'umuzenguruko, aho gufatwa nk'igihagarika cyclase gusa. Bitewe n'uburyo icyitegererezo cyateguwe n'ubwibande, bushobora kugabanya ukwifatanya kw'ibintu bigenzura iyandukurwa rya iNOS, guhagarika enzime NOS ku buryo butaziguye, kugabanya ukuboneka kwa okiside ya azote butuma hakorwa superokiside, no kubangamira cyclase yakanguriwe na okiside ya azote. Uruhare rw'ubutumwa bwa GMP y'umuzenguruko mu bushakashatsi ku miyoboro y'amaraso n'igereranya ry'ibintu bitanga okiside ya azote bikoreshwa mu magerageza ku ngirabuzimafatizo buri kimwe gisobanura imwe muri izo nzira mu buryo burambuye. Uburyo bukoreshwa mu gutandukanya ingaruka zo gutakaza no kwakira elegitoroni n'ingaruka kuri enzime busobanura impamvu superoxide dismutase, catalase, n'ikigereranyo gikoresha ikintu gihamye gitanga okiside ya azote bikunze kugaragara hamwe muri ubwo bushakashatsi.

Igipimo gito cya GMP y'umuzenguruko nyuma yo gukoresha ubururu bwa metilene kigaragaza urunigi rwacitse. Ibigereranyo byonyine ni byo bivuga igice cyacitse.