Umsebenzi we-Renin Enzyme ekulawulweni kokucindezeleka kwegazi
Umfutho wegazi uyipharamitha ebalulekile enquma ukusebenza kahle kohlelo lokujikeleza kwegazi. Uma umfutho wegazi uphansi kakhulu, ukunikezwa komoya-mpilo nezakhamzimba ezithweni ezibalulekile kungaphazamiseka. Ngokuphambene nalokho, uma uphezulu kakhulu futhi uhlala isikhathi eside, ungalimaza imithambo yegazi futhi wandise ingozi yesifo senhliziyo, isifo sohlangothi, kanye nokuphazamiseka kwezinso. Umzimba unezindlela ezahlukahlukene zokugcina umfutho wegazi uzinzile, enye yazo ngokusebenzisa isenzo se-enzyme i-renin. I-Renin iyisici esibalulekile sohlelo lwe-renin–angiotensin–aldosterone (RAAS), uchungechunge lwezimpendulo zamahomoni ezilawula umfutho wegazi kanye nokulinganisela koketshezi emzimbeni. Lesi sihloko sixoxa ngomsebenzi we-enzyme i-renin, indlela esebenza ngayo, izici eziwuthonyayo, kanye nokubaluleka kwayo kwezokwelapha.
Kuyini i-renin?
I-Renin iyi-protease (i-enzyme ephula amaprotheni) ekhiqizwa ngokuyinhloko ngamaseli e-juxtaglomerular ezinso. Lawa maseli atholakala ezindongeni ze-arteriole ye-afferent, umthambo wegazi omncane othwala igazi uye e-glomerulus (iyunithi yokuhlunga yezinso). I-Renin ayisebenzi yodwa; iqala "ukusabela kweketanga" okuphetha ngokwakhiwa kwama-hormone angakhuphula umfutho wegazi. Ngamanye amazwi, i-renin iyisisusa sokuqala senye yezinhlelo ezibaluleke kakhulu zomzimba ezilawula umfutho wegazi.
Ikhishwa nini i-renin?
Ukukhishwa kwe-renin kwenzeka lapho umzimba uthola izimo eziholela ekunciphiseni ukugeleza kwegazi (ukugeleza) noma ukwehla komthamo woketshezi. Ngokuvamile, i-renin iyanda uma:
1. Ukwehla kwengcindezi yokugeleza kwegazi ezinso
Isibonelo, ezimweni zokuphelelwa amanzi emzimbeni, ukopha, noma ukwehla okungazelelwe komfutho wegazi, izinso "zifunda" lezi zimo njengezimpawu eziphuthumayo zokugcina ukujikeleza kwegazi.
2. Amazinga e-sodium chloride (NaCl) ku-distal tubule ayancipha
Le sensor yenziwa ngamaseli e-macula densa (ingxenye yedivayisi ye-juxtaglomerular). Uma i-NaCl ephansi ifinyelela ku-macula densa, ngokuvamile ikhombisa ukwehla kokuhlungwa kwezinso noma ukwehla kwevolumu yoketshezi lomzimba, okuholela ekukhishweni kwe-renin.
3. Ukuvuselelwa okwengeziwe kwesimiso sezinzwa esinozwela
Ngesikhathi sokucindezeleka, ubuhlungu, izinguquko esimweni (isib. ukuma ngokuzumayo), noma ukushaqeka, uhlelo lozwela luyavuselelwa futhi luvuselele ama-receptor e-β1 kumaseli e-juxtaglomerular ukuze akhulule i-renin.
Lezi zindlela ezintathu zibonisa ukuthi i-renin isebenza njengempendulo eguquguqukayo yomzimba ukuze kulondolozwe umfutho wegazi kanye nokuphakelwa kwegazi ezithweni zomzimba.
Indlela yokusebenza kwe-renin ku-RAAS
Indima kaRenin ekulawulweni komfutho wegazi yenzeka nge-RAAS. Ukulandelana kwezinqubo kungachazwa kanje:
1. I-Renin iphula i-angiotensinogen ibe yi-angiotensin I
I-Angiotensinogen iyiprotheni ekhiqizwa yisibindi futhi ijikeleza egazini. I-Renin ihlukanisa i-angiotensinogen ibe yi-angiotensin I, ehlala ingasebenzi kangako.
2. I-Angiotensin I iguqulwa ibe yi-angiotensin II yi-ACE
I-enzyme eguqula i-angiotensin (ACE) itholakala kakhulu endothelium yemithambo yegazi, ikakhulukazi emaphashini. I-ACE iguqula i-angiotensin I ibe yi-angiotensin II, i-molecule esebenzayo enamandla kakhulu ekunyuseni umfutho wegazi.
3. I-Angiotensin II inyusa umfutho wegazi ngezindlela eziningana.
I-Angiotensin II isebenza “njengephakheji ephelele” yokuphakamisa umfutho wegazi, okuhlanganisa nalokhu:
– Ukuncishiswa kwemithambo yegazi (ukuncishiswa kwemithambo yegazi): Imithambo yegazi iyancishiswa ukuze ukumelana kwangaphakathi kukhuphuke, futhi umfutho wegazi ukhuphuke.
– Kukhuthaza ukukhishwa kwe-aldosterone ezindlaleni ze-adrenal: I-Aldosterone yandisa ukumuncwa kabusha kwe-sodium namanzi ezinso, ngaleyo ndlela yandisa umthamo wegazi.
– Kukhuthaza ukukhishwa kwe-ADH (vasopressin): I-ADH yandisa ukumuncwa kwamanzi ezinso, okwandisa umthamo woketshezi.
– Ukwanda kokoma: Umzimba ukhuthazwa ukuphuza kakhulu, ngaleyo ndlela kusiza ukwandisa umthamo woketshezi.
– Ithinta ithoni yozwela: I-Angiotensin II ingaqinisa umsebenzi wozwela, okwandisa nomfutho wegazi.
Ngakho-ke, i-renin isebenza “njengokushintsha kokuqala” okuvuselela ukusabela kweketanga kuze kube yilapho umfutho wegazi kanye nomthamo wokujikeleza kwegazi ekugcineni kukhuphuka.
I-Renin kanye nebhalansi yoketshezi kanye ne-electrolyte
Ukulawulwa komfutho wegazi akuhlukaniseki nokulawulwa koketshezi kanye ne-electrolyte. Kulesi simo, i-renin, nge-RAAS, idlala indima enkulu ekugcineni amazinga e-sodium namanzi. Kubalulekile ukukhumbula ukuthi i-sodium inomphumela "wokugcina amanzi" emzimbeni. Lapho i-aldosterone ikhula, izinso zigcina i-sodium eningi; amanzi nawo ayagcinwa, okwandisa umthamo wegazi. Lokhu kwanda komthamo wegazi ekugcineni kunegalelo ekwandeni komfutho wegazi.
Kodwa-ke, le ndlela yokusebenza kumele ilinganiswe. Uma i-RAAS isebenza ngokweqile, ukugcinwa kwe-sodium namanzi ngokweqile kungabangela ukuvuvukala (ukuvuvukala) futhi kwandise umthwalo womsebenzi wenhliziyo. Kwezinye izimo zezokwelapha, ukusebenza kwe-RAAS kuyisici esibalulekile ekuqhubekeni kwesifo.
Indlela yokuphendula ukuze ugweme ukuyenza ngokweqile
Umzimba unesistimu yokuphendula ukuze uvimbele ukwanda okungalawuleki komfutho wegazi. Lapho umfutho wegazi kanye nokugeleza kwegazi ezinso kuthuthuka, noma lapho ukungenisa i-sodium noketshezi kwanele, ukukhishwa kwe-renin kuyancipha. I-Angiotensin II ingaphinde inikeze impendulo engemihle, ivimbele ukukhishwa kwe-renin okwengeziwe.
Ngaphezu kwalokho, kunezihomoni ezisebenza ngokumelene ne-RAAS, njenge-ANP (i-atrial natriuretic peptide), ekhishwa yinhliziyo uma umthamo wegazi uphezulu kakhulu. I-ANP ikhuthaza ukukhishwa kwe-sodium namanzi ngezinso, ngaleyo ndlela inciphise umthamo wegazi kanye nomfutho, kuyilapho ngesikhathi esifanayo icindezela umsebenzi we-RAAS.
Izici ezithinta amazinga e-renin
Amazinga e-renin angahluka phakathi kwabantu nezimo. Ezinye izici ezingandisa i-renin zifaka:
– Ukuphelelwa amanzi emzimbeni noma ukuntuleka koketshezi
- Ukudla okunosawoti omncane
– Ukopha
– Ukuma isikhathi eside (ukushintsha ukuma kusuka ekulaleni kuya ekumeni)
– I-Renal artery stenosis (ukuncipha kwemithambo yegazi yezinso)
- Ukusebenza okuzwela kakhulu
Ngakolunye uhlangothi, i-renin ingancipha ezimweni ezifana nalezi:
– Ukudla usawoti omningi
– Izifo ezithile ezine-aldosterone eningi (i-primary hyperaldosteronism)
– Ukwanda komthamo wegazi
- Ukusetshenziswa kwemithi ethile ecindezela i-RAAS
Ukubaluleka kwezokwelapha: kungani i-renin ibalulekile ku-hypertension?
I-Renin idlala indima ebalulekile ezimweni eziningi zomfutho wegazi ophakeme (umfutho wegazi ophezulu), ikakhulukazi lezo ezihlobene nezinso noma ama-hormone. Isibonelo, ekushayweni yi-renal artery stenosis, izinso zithola ukugeleza kwegazi okunciphile, okubangela ukuba "zicabange" ukuthi umzimba uphansi ngevolumu. I-Renin iyanda, i-RAAS iyasebenza, futhi umfutho wegazi ophakeme. Lesi simo siyisibonelo esivamile sendlela ukungasebenzi kahle kwezinso kwendawo okungabangela ngayo umfutho wegazi ophakeme ojwayelekile.
Kwezokwelapha, ukuhlolwa kwe-plasma renin kanye ne-aldosterone kungasiza odokotela ukuthi bahlole ukuthi umfutho wegazi ophakeme ubangelwa yini yizinkinga ezithile zama-hormone. Isilinganiso se-aldosterone-renin sivame ukusetshenziselwa ukuhlola i-primary hyperaldosteronism.
URenin njengomgomo wokwelashwa ngemithi
Ngenxa yokuthi i-RAAS ibaluleke kakhulu ekulawuleni umfutho wegazi, imithi eminingi yokulwa nomfutho wegazi ophezulu ihlose le ndlela, njenge:
– I-ACE inhibitor (ivimbela ukwakheka kwe-angiotensin II)
– I-ARB (i-angiotensin receptor blocker) (ivimbela ukusebenza kwe-angiotensin II kuma-receptor ayo)
- I-Aldosterone antagonist (ivimbela imiphumela ye-aldosterone)
- Ama-renin inhibitors aqondile (isb. i-aliskiren, evimbela isinyathelo sokuqala, umsebenzi we-renin)
Le mithi ayigcini nje ngokwehlisa umfutho wegazi, kodwa futhi ivame ukusetshenziselwa ukuvikela izitho eziqondiwe njengenhliziyo nezinso ezimweni ezithile.
Isiphetho
I-enzyme i-renin iyisici esibalulekile ekulawulweni komfutho wegazi ngoba iyisisusa sokuqala sokusebenza kohlelo lwe-renin-angiotensin-aldosterone. I-Renin ikhishwa ikakhulukazi lapho umzimba uhlangabezana nokuncipha kokugeleza kwegazi kwezinso, ukwehla kwe-sodium ku-distal tubule, noma ukwanda komsebenzi wokuzwela. Ngokwakhiwa kwe-angiotensin II kanye nokwanda kwe-aldosterone ne-ADH, i-RAAS ikhuthaza ukuqina kwemithambo yegazi kanye nokugcinwa kwamanzi e-sodium, ekugcineni iphakamisa umfutho wegazi futhi igcine ukuqina kokujikeleza kwegazi. Ibhalansi ye-renin ibalulekile: amazinga aphansi kakhulu noma aphezulu kakhulu angabangela ukuphazamiseka komfutho wegazi. Ngakho-ke, i-renin kanye nendlela ye-RAAS kubalulekile ekuqondeni umfutho wegazi ophakeme futhi kuyizinhloso ezibalulekile zokwelapha eziningi zanamuhla.
