Buluu wa methylene ndi nayitriki okisayidi: NOS, cGMP, mauthenga m'mitsempha ya magazi

Funso lake likumveka losavuta: kodi buluu wa methylene amalepheretsa nayitriki okisayidi? Mu labotale, yankho limagawika kukhala mafunso anayi osiyana, ndipo lililonse lili ndi mayeso ake osiyana. Kusokoneza mafunsowa ndi chifukwa chachikulu chimene zolemba zokhudza buluu wa methylene ndi nayitriki okisayidi zimamveka zotsimikiza koma zosamveka bwino.

Ganizirani uthenga wa nayitriki okisayidi ngati unyolo wa maulalo anayi. Uthenga wa jini umakopedwa kuti apange nayitriki okisayidi synthase. Enzayimuyi imasintha arginine kukhala nayitriki okisayidi. Mpweyawu umafalikira kufika kumene ukuyenera kugwira ntchito usanachite zochitika za mankhwala ndi chinthu china. Guanylate cyclase yosungunuka imauzindikira n'kupanga cyclic GMP. Pali kafukufuku wofalitsidwa wosonyeza zochita za buluu wa methylene pa ulalo uliwonse, koma umboniwo umachokera ku zinthu zokonzedwa m'njira zosiyana, milingo ya kuchuluka kosiyana, ndi mitundu yosiyana ya enzayimu. Zotsatira pa ulalo umodzi sizitsimikizira kuti wachitaponso kanthu pa wina.

Unyolo wodziwika bwino, wofotokozedwa momveka

M'khoma la mtsempha wa magazi, zinthu zimachitika motsatizana motere. Chinthu cholimbikitsa chimakhudza selo la endothelium. Nayitriki okisayidi synthase ya endothelium, yotchedwa eNOS kapena NOS3, imapanga nayitriki okisayidi pang'ono kwa kanthawi. Mpweyawu umafalikira kulowa mu selo la minofu yosalala loyandikana nalo, umamangirira ku heme yokhala ndi ayironi yomwe yalandira ma elekitironi ya guanylate cyclase yosungunuka, ndipo umafulumizitsa kusintha kwa GTP kukhala cyclic GMP. Cyclic GMP imayambitsa protein kinase G, kayendetsedwe ka calcium kamasintha, ndipo minofuyo imamasuka.

Pali unyolo wachiwiri umene tiyenera kuusiyanitsa ndi woyamba. Pakakhala matenda obwera chifukwa cha tizilombo kapena maselo akakumana ndi cytokine, maselowo amakopera uthenga wa jini kuti apange enzayimu ina, nayitriki okisayidi synthase yoyambitsidwa ndi zinthu zina, kapena iNOS, yotchedwanso NOS2. Imatulutsa nayitriki okisayidi yochuluka komanso kwa nthawi yaitali kuposa eNOS. Mtundu wachitatu, NOS ya maselo a minyewa kapena nNOS, umagwira ntchito m'zochitika zinanso. Ngati pepala la kafukufuku likunena nayitriki okisayidi synthase popanda kutchula mtundu wake, imani kaye n'kuona kuti ndi uti umene unayesedwa. Kufotokoza mmene buluu wa methylene amasamutsira ma elekitironi kumatsindikanso mfundo yomweyi pa zinthu zimene zimakhudzidwa ndi redox: njira yosamutsirayo siichita chilichonse pa yokha, ndipo chinthu chimene imagwirizana nacho kumbali iliyonse ndicho chimatsimikizira zotsatira.

Cyclic GMP yoyezedwa imasonyezanso zotsatira zophatikizidwa, osati kuyesa enzayimu mwachindunji. Kuchuluka kwake kumasonyeza kupanga kwa cyclase kuchotsera kuwonongedwa ndi phosphodiesterases, makamaka PDE5 m'minofu yosalala ya mitsempha ya magazi. Choncho kuchepa kwa cyclic GMP kumatanthauza kuti uthenga wochepa wafika ku chinthu chozindikira uthengawo. Pa kokha, sikutchula ulalo umene walephera.

Ulalo 1: enzayimu ya iNOS yochepa imapangidwa

M'maselo a macrophage a mbewa amene analimbikitsidwa ndi lipopolysaccharide ya mabakiteriya, interferon gamma, kapena zonsezi, buluu wa methylene analetsa kukwera koyembekezeredwa kwa puloteni ya iNOS ndipo anachepetsa kwambiri RNA yonyamula uthenga wa iNOS mu mayeso a kukopera uthenga wa jini m'maselo a macrophage. Mbali yothandiza kumvetsetsa ndi zinthu zimene sizinasinthe. Kuwonongeka kwa chinthu choletsa chotchedwa I kappa B alpha, kuwonjezeredwa kwa phosphate ku NF kappa B ndi STAT1, komanso kulowa kwa zinthuzi m'phata la selo zinapitirirabe makamaka popanda kusintha. Chimene chinachepa chinali kumangirira kwawo ku DNA, monga zinatsimikiziridwa ndi mayeso a chromatin immunoprecipitation osonyeza kuchepa kwa kumangirira pa malo oyambitsira kukopera uthenga wa jini ya iNOS.

Izi ndi zotsatira pa kayendetsedwe ka jini zomwe zimachitika enzayimu isanapangidwe mochuluka, osati kutsekereza mwamsanga enzayimu yomwe ilipo kale. Zimakhudza kutumiza mauthenga pa kutupa, pamene zinthu zoyendetsa kukopera uthenga wa jini ziyenera kumangirira ku malo oyambitsira kukoperako puloteni isanapangidwe. Sizikunena chilichonse mwachindunji chokhudza eNOS yomwe imakhalapo nthawi zonse mu mtsempha wosakondoweza, ndipo ziyenera kufotokozedwa choncho.

Ulalo 2: enzayimu ya NOS yomwe ilipo kale imagwira ntchito pang'onopang'ono

Kafukufuku wa makoswe anayesa gawo lina. Makoswe aamuna omwe anali ogalamuka anapatsidwa lipopolysaccharide kudzera mumtsempha wa magazi. Patapita maola atatu, anapatsidwa madzi amchere kapena buluu wa methylene pa 3 mg per kg kudzera mumtsempha wa magazi, ndipo ntchito ya nayitriki okisayidi synthase m'chigawo chapakati cha pansi pa hypothalamus inayezedwa mwa kusintha arginine yokhala ndi chizindikiro chotsatirika kukhala citrulline mu kafukufuku wa ntchito ya NOS mu hypothalamus. Kupsinjika pamodzi ndi madzi amchere okha kunayambitsa ntchito ina yosadalira calcium, ndipo lipopolysaccharide inakweza ntchitoyo kufika pafupifupi kakhumi pa mulingo wa gulu loyerekezeramo. Buluu wa methylene anachotsa ntchito zonse ziwiri zoyambitsidwazo. Ntchito yodalira calcium yomwe imakhalapo nthawi zonse sinasinthe m'minofu imeneyo pa kuchuluka ndi nthawi ya kuyeza imeneyo.

Werengani zotsatirazo monga zalembedwera: ntchito yoyezedwa ya mtundu wa iNOS inachepetsedwa m'mikhalidwe imeneyo. Uku sikunali kuyeza kupangidwa kwa zinthu motsatira uthenga wa jini, ndipo si umboni wakuti nthawi zonse amasankha iNOS osati eNOS kapena nNOS. Kafukufuku wa enzayimu yoyengedwa umatsindika kufunika kosamala kumeneku. Poyesa mwachindunji nayitriki okisayidi synthase yoyengedwa, buluu wa methylene analetseratu kupangidwa kwa citrulline pa 30 micromolar. Kuchuluka kwake koletsa theka la ntchitoyo kunali pafupifupi 5.3 micromolar popanda superoxide dismutase ndi 9.2 micromolar ikakhalapo, monga ananenera mu kuyerekezera NOS yoyengedwa ndi guanylate cyclase. Kafukufuku wina wa nNOS yoyengedwa anasonyeza kuti kutayika kwa ma elekitironi kwa heme yomangiriridwa ku enzayimu kunali ndi mbali pa zotsatirazo. Phunziro lofunika ndi lakuti kulepheretsa NOS mwachindunji kumachitikadi m'zinthu zolekanitsidwa, koma zotsatira za hypothalamus sizingafutukulidwe kukhala mawu oti buluu wa methylene samakhudza NOS zonse zomwe zimakhalapo nthawi zonse kulikonse.

Ulalo 3: nayitriki okisayidi imatayika isanafike

Umboni womveka bwino kwambiri wakuti chinthu china osati kutsekereza enzayimu chingafotokoze kuchepa kwa cyclic GMP umachokera ku maselo a minofu yosalala ya mtsempha wa m'mapapo wa kalulu amene anakulitsidwa mu labotale. Mayesowo analumpha ntchito ya NOS yopangidwa mkati mwa maselo powonjezera mwachindunji zinthu zotulutsa nayitriki okisayidi, kenako n'kufunsa ngati buluu wa methylene ankachepetsabe kuyankha kwa cyclic GMP mu kafukufuku wa superoxide m'minofu yosalala ya mitsempha ya magazi.

Zinthu zitatu zotulutsa nayitriki okisayidi zinayesedwa kuyambira 1 mpaka 100 micromolar: S nitroso L cysteine, sodium nitroprusside, ndi chinthu chokhazikika chofanana nacho chomwe chinachotsedwa gulu la amino, chotchedwa MPANO. Zonse zinakweza cyclic GMP kufika pafupifupi nthawi 1.5 mpaka nthawi 12. Buluu wa methylene pa 10 micromolar analepheretsa ziwiri zoyambazo ndi 51 mpaka 100 peresenti ndipo sanasinthe kuyankha kwa MPANO. Ngati buluu wa methylene ankangotsekereza malo ogwirira ntchito a cyclase, kusankha kwake pakati pa zinthu zotulutsa nayitriki okisayidizi kukanakhala kovuta kufotokoza, chifukwa zonse zitatu zimafikira enzayimu yomweyo pa gawo lotsatira.

Kenako mayeso atatu oyerekezeramo anatsimikizira kuti njirayo inakhudza superoxide. Choyamba, kupanga superoxide kunja kwa maselo pogwiritsa ntchito xanthine pamodzi ndi xanthine oxidase kunabweretsa zotsatira zofanana: CYSNO ndi nitroprusside zinalepheretsedwa, koma MPANO sinakhudzidwe. Chachiwiri, buluu wa methylene anachititsa maselo a minofu yosalala kupanga superoxide molingana ndi kuchuluka kwake ndi nthawi, ndipo izi zinayesedwa mwa kulandira ma elekitironi kwa cytochrome c. Chachitatu, superoxide dismutase inaletseratu kulepheretsedwako pamene catalase sinatero. Izi zikusonyeza kuti superoxide, osati hydrogen peroxide, ndiyo inachititsa zotsatirazo mwachindunji mu maselo okonzedwa amenewo.

Mtundu wa mayesowo umene maselo anakulitsidwa pamodzi ndi wofunika kufotokozedwa chifukwa umasonyeza kumene zotsatirazo zinachitikira. Maselo a endothelium omwe anali pa timagalasi tophimbira anakulitsidwa pamodzi ndi maselo a minofu yosalala kwa kanthawi, kotero kuti chinthu chotulutsidwa ndi endothelium popanda kulimbikitsidwa chinakweza cyclic GMP ya minofu yosalala kufika katatu mpaka kasanu ndi katatu. Kuchitira mbali iliyonse ndi buluu wa methylene pasadakhale kunachepetsa uthengawo, ndipo superoxide dismutase inabwezeretsa pang'ono zotsatira za kuchitira maselo a endothelium pasadakhale. M'mawu ena, buluu wa methylene safunikira kugwira ntchito mkati mwa selo la minofu yosalala lozindikira uthenga. Angachepetse uthengawo pochotsa chinthu chonyamula uthengawo chili panjira. Kalozera wa kuwerenga kafukufuku wa buluu wa methylene amaona izi ngati lamulo lofala: tchulani kaye mbali imene chinthucho chinagwiritsidwa ntchito musanatchule molekyulu imene chikukhudza.

Kutchula izi kuti kulepheretsa NOS kungakhale kolakwika. Zinthu zotulutsa nayitriki okisayidizi sizinafunikire gawo la synthase kuti zigwire ntchito, komabe uthengawo unachepabe.

Ulalo 4: chozindikira uthengacho chimayankha mochepa

Zotsatira zachindunji pa guanylate cyclase yosungunuka zilipo, koma kuchuluka kwa buluu wa methylene n'kofunika. Mu kuyerekezera enzayimu yoyengedwa komwe kwatchulidwa pamwambapa, cyclase yolimbikitsidwa ndi nayitriki okisayidi inafunikira buluu wa methylene pafupifupi 60 micromolar kuti theka la ntchito yake lilepheretsedwe, poyerekeza ndi kulepheretsa theka la ntchito ya NOS pa pafupifupi 5 mpaka 9 micromolar. Ngakhale 1 millimolar inangobweretsa kutsekereza kosakwanira pa mulingo wake wapamwamba kwambiri. Uku ndi kusiyana kwa pafupifupi nthawi zisanu ndi chimodzi mpaka khumi ndi imodzi. Choncho mayeso a maselo ogwiritsa ntchito kuchuluka kochepa kwa micromolar amene amachepetsa cyclic GMP sangatchedwe kulepheretsa cyclase mosankha chifukwa cha chiwerengero cha cyclic GMP chokha.

Kafukufuku wa redox womwe unachitika pambuyo pake unawonjezera chenjezo lina: buluu wa methylene anazimitsa ntchito ya cyclase yoyambitsidwa ndi nayitriki okisayidi mwa njira yosiyana ndi kungotayika kwa ma elekitironi kwa ayironi ya heme chifukwa cha mpweya. Choncho chozindikira uthenga chingasokonezedwe, koma mmene zochitika za mankhwalazi zimagwirira ntchito sikunatsimikizidwe mokwanira. Ndipo kusiyana kwa kuchuluka kofunika kukusonyeza kuti pa milingo yochepa ya micromolar, zotsatira za superoxide ndi NOS ziyenera kuyesedwa ndi kuchotsedwa ngati zifukwa kaye. Apa ndipamenenso kuyesa kulamulira ntchito ya phosphodiesterase kumafunika. Ngati kuwonongeka kwa cyclic GMP sikunayezedwe kapena kutsekerezedwa, kuchepa kwa cyclic GMP yomwe yaunjikana kungagwirizane ndi kupanga kochepa, kuwonongeka kofulumira, kapena zonsezi.

Chifukwa chake izi sizingafupikitsidwe kukhala mawu amodzi okhudza kuthamanga kwa magazi

Ulalo uliwonse unatsimikiziridwa mu dongosolo losiyana. Kukopera uthenga wa jini m'maselo a macrophage sikuli kofanana ndi ntchito ya enzayimu mu hypothalamus. Ntchito ya hypothalamus pambuyo pa lipopolysaccharide sikuli kofanana ndi mmene endothelium imasungira kulimba kwa mtsempha popanda kulimbikitsidwa. Chinthu chotulutsidwa ndi endothelium popanda kulimbikitsidwa m'maselo okulitsidwa pamodzi sikuli kofanana ndi kukula kwa mitsempha komwe kwalimbikitsidwa ndi chinthu choyambitsa kuyankha. Maselo a mtsempha wa m'mapapo okulitsidwa mu labotale amene ali pa buluu wa methylene 10 micromolar sali ofanana ndi kayendedwe ka magazi ka munthu. Kuphatikiza zonsezi kukhala mawu akuti buluu wa methylene amakweza kuthamanga kwa magazi potsekereza nayitriki okisayidi kumataya kusiyana kwenikweni kumene mayeso oyerekezeramo anakonzedwa kuti asunge.

Kufufuza zinthu zitatu kumathandiza kufotokoza nkhaniyi molondola. Choyamba, tchulani mtundu wa enzayimu: eNOS pa kulimba kwa mitsempha ya magazi popanda kulimbikitsidwa, iNOS pa kutulutsa nayitriki okisayidi koyambitsidwa pa kutupa, ndi nNOS pa zochitika za maselo a minyewa ndi zina za enzayimu yoyengedwa. Chachiwiri, tchulani mmene uthenga wa nayitriki okisayidi unaperekedwera: kupanga mkati mwa maselo, kutulutsa kwa endothelium popanda kulimbikitsidwa, kapena chinthu china chotulutsa nayitriki okisayidi monga CYSNO, nitroprusside, kapena MPANO. Izi n'zofunika chifukwa chinthu chokhazikikacho sichinakhudzidwe ndi buluu wa methylene pamene zosakhazikikazo zinakhudzidwa. Chachitatu, tchulani kuchuluka kwake ndi chimene chinabwezeretsa zotsatirazo: kubwezeretsa ndi superoxide dismutase kumasonyeza kuti superoxide ili ndi mbali, kulephera kwa catalase kumatsutsa kuti hydrogen peroxide ndiyo chifukwa mu zinthu zokonzedwa zimenezo, kutsanzira kwa xanthine oxidase kumasonyeza kuti superoxide yokha ndi yokwanira kubweretsa zotsatirazo, ndipo mayeso a enzayimu yoyengedwa amasiyanitsa zotsatira zachindunji pa ntchito yosinthira zinthu ndi kutayika kwa uthenga uli panjira.

Mwachidule, tingati izi. Ndi bwino kuona buluu wa methylene ngati chinthu chosokoneza malo angapo pa njira ya uthenga kuchokera ku nayitriki okisayidi kupita ku cyclic GMP, osati ngati chinthu chotsekereza cyclase yokha mosankha. Kutengera mmene zinthu zakonzedwera ndi kuchuluka kwake, angachepetse kumangirira kwa zinthu zoyendetsa kukopera uthenga wa jini ya iNOS, angalepheretse enzayimu za NOS mwachindunji, angachepetse kupezeka kwa nayitriki okisayidi mwa kupanga superoxide, ndipo angasokoneze cyclase yoyambitsidwa ndi nayitriki okisayidi. Ntchito ya kutumiza mauthenga kwa cyclic GMP mu kafukufuku wa mitsempha ya magazi ndi kuyerekezera zinthu zotulutsa nayitriki okisayidi zomwe zimagwiritsidwa ntchito poyesa maselo iliyonse imafotokoza mwatsatanetsatane nthambi imodzi mwa zimenezi, ndipo njira zomwe zimagwiritsidwa ntchito kusiyanitsa zotsatira za redox ndi zotsatira pa enzayimu zimafotokoza chifukwa chake superoxide dismutase pamodzi ndi catalase komanso chinthu chokhazikika chotulutsa nayitriki okisayidi choyerekezeramo zimapezeka kawirikawiri m'mabuku a kafukufuku amenewa.

Kuchuluka kochepa kwa cyclic GMP pambuyo pa buluu wa methylene kumasonyeza unyolo wosweka. Mayeso oyerekezeramo okha ndi amene amanena ulalo umene wasweka.