Ngisho nangaphambi kokuba kutholwe i-insulin, amaqembu ahlukahlukene amaseli atholakala eziqhingini zepancreatic.
I-glucagon ye-hormone ngokwayo yatholakala nguMerlin noKimball ngonyaka we-1923, kepha bambalwa ababenesifiso sokutholwa ngaleso sikhathi, futhi kwaba yiminyaka engama-40 kuphela kamuva kwacaca ukuthi le hormone idlala indima ebaluleke kakhulu ngokomzimba ekumetheni kwemizimba ye-ketone neglucose.
Ngaphezu kwalokho, indima yayo njengesidakamizwa njengamanje ayibalulekanga.
Izici zamakhemikhali
IGlucagon iyinhlangano eyodwa ye-polypeptide eyodwa enezinsalela ezingama-29 ze-amino acid. I-Homology ebalulekile ephakathi kwe-glucagon namanye ama-hormone e-polypeptide, afana ne
- umfihlo
- ipeptide evimbela igesi,
- I-VIP.
Ukulandelana kwe-amino acid kule hormone kuyafana ezilwaneni eziningi ezincelisayo kuyafana nasezingulubeni, kubantu, kumagundane nasezinkomeni; kuyi-pancreatic hormone.
Umsebenzi womzimba kanye neqhaza le-glucagon precursors alikakacaciswa. Kepha kunombono osuselwa kusimiso esiyinkimbinkimbi sokucushwa kwe-preroglucagon ukuthi bonke banemisebenzi ekhethekile.
Emangqamuzaneni esiqiwi se-pancreas kukhona imicwecwana eyimfihlo, ehlukanisa umongo ophakathi nendawo, oqukethe i-glucagon nomugqa wangaphandle we-glycine. Ama-L-cell atholakale emathunjini aqukethe iminsalo equkethe i-glycine kuphela.
Ngokunokwenzeka, kula maseli ama-pancreas awekho ama-enzyme aguqula i-glycine ibe yi-glucagon.
I-Oxyntomodulin ivuselela i-adenylate cyclase ngokubopha kuma-glucagon receptors akhiwe kuma-hepatocytes. Umsebenzi wale peptide ucishe ube ngama-20% walokho okushukela.
Iprotheni enjenge-glucagon yohlobo lokuqala isebenza ngamandla ukukhipha i-insulin, kepha ngasikhathi sinye ayithinti i-hepatocytes.
Ama-glycine, ama-peptides afana ne-glucagon ne-oxyntomodulin atholakala ikakhulu emathunjini. Ngemuva kokususwa kwama-pancreas, secretion ye-glucagog iyaqhubeka.
Ukulawulwa kwezimfihlo
Ukukhuphuka kwe-glucagon, futhi ukwakheka kwayo yisenzo lapho i-glucose ibhekele khona ukudla, kanye ne-insulin, okunamafutha acid nama-amino acid. I-glucose iyi-inhibitor enamandla yokwakheka kwe-glucagon.
Inethonya elinamandla ekukhusekeni nasekuhlanganiseni kwaleli hormone lapho lithathwe ngomlomo kunangesikhathi ihanjiswa ngaphakathi, lokhu kukhonjiswa ngemiyalo yokusebenzisa.
Ngendlela efanayo, ushukela wenza ngoku secretion we-insulin. Ngokunokwenzeka, lo mphumela uhlotshaniswa nesenzo sama-hormone wokugaya ukudla futhi ulahlekile ekunxephezelweni kahle kwesifo sikashukela i-mellitus (ukuxhomekeka kwe-insulin) noma uma kungekho ukwelashwa kwaso.
Akukho esikweni lama-a-cell. Okusho ukuthi, singaphetha ngokuthi umphumela we-glucose kuma--cell, ngokwezinga elithile, kuya ngokusebenza kwawo kokulungiswa kwe-insulin. Ama-acid wamahhala wamahhala, imizimba ye-somatostatin ne-ketone nayo ivimbela ukufihlakala namazinga e-glucagon.
Ama-amino acid amaningi athuthukisa ukukhululeka kwe-insulin ne-glucagon. Yingakho ngemuva kokudla ukudla okubandakanya amaprotheni kuphela, umuntu akaqali i-hypoglycemia eqondiswe yi-insulin futhi yonke imisebenzi ye-pancreatic iqhubeka isebenza ngokujwayelekile.
Njenge-glucose, ama-amino acid anomphumela omkhulu lapho uthathwa ngomlomo kunalapho ufakwe khona. Okusho ukuthi, umphumela wazo uhlotshaniswa ngokwengxenye nama-hormone wokugaya ukudla. Ngaphezu kwalokho, ukukhululeka kwe-glucagon kulawulwa uhlelo lwezinzwa lwe-autonomic.
Ukuqunjelwa kanye nokuhlanganiswa kwaleli hormone kukhuliswa ngokucasulwa kwemicu yezinzwa enozwela ebhekene nokufakwa ngaphakathi kweziqunjelwa ze-pancreatic, kanye nokwazisa kwe-sympathomimetics kanye ne-adrenostimulants.
I-metabolabolism ne-glucagon synthesis kususelwa kulemigomo elandelayo:
- IGlucagon iba nokubhujiswa okusheshayo esibindini, e-plasma nasezinso, nakwezinye izicubu ezihlosiwe.
- I-plasma yayo isigamu-lokuphila yimizuzu engu-3-6 kuphela.
- I-hormone ilahlekelwa umsebenzi wayo wezinto eziphilayo lapho ama-protein eqeda izinsalela ze-N-terminal histidine.
Indlela yokusebenza
I-Glucagon ibopha i-receptor ethile etholakala kulwelwesi lwamaseli kwelitshe. Le receptor iyi-glycoprotein ethize yesisindo.
Okwamanje akukwenzeki ukuthi kuqondwe ngokuphelele ukwakheka kwawo, kepha kuyaziwa ukuthi iboshelwe kumaprotheni e-Gj enza ukuthi kusebenze i-adenylate cyclase futhi kuthinte ukwakheka kwayo.
Umphumela oyinhloko we-glucagon kuma-hepatocytes wenzeka nge-cyclic AMP. Ngenxa yokuguqulwa kwengxenye ye-N-ukuphela ye-molecule ye-glucagon, iguqulwa ibe i-agonist eyingxenye.
Ngenkathi igcina ukuvumelana kwe-receptor, amandla ayo okwenza kusebenze i-adenylate cyclase ilahlekile kakhulu. Lokhu kuziphatha kubhekiswa ku-des-His - [Glu9] -glucagonamide kanye no- [Phen] -glucagon.
Le enzyme inquma ukugxila kwe-intracellular ye-fructose-2,6-diphosphate, ethinta i-glycogenolysis ne-gluconeogenesis.
Uma izinga le-glucagon liphezulu futhi ukuvela kushesha, khona-ke ngenani elincane le-insulin phosphorylation le-6-phosphofructo-2-kinase / fructose-2,6-diphosphatase kwenzeka futhi iqala ukusebenza njenge-phosphotase.
Kulokhu, inani le-fructose-2,6-diphosphate esibindini liyancipha. Ngokugcwala okukhulu kwe-insulin kanye nenani elincane le-glucagon, i-dephosphorylation ye-enzyme iqala, futhi isebenza njenge-kinase, ikhulisa izinga le-fructose-2,6-diphosphate.
Le khompiyutha iholela kusebenze kwe-phosphofrafokinase - i-enzyme esheshisa ukusabela komkhawulo kwe-glycolysis.
Ngakho-ke, ngobuningi be-glucagon, i-glycolysis ivinjelwe futhi i-gluconeogeneis iyathuthukiswa, futhi ngokuqukethwe okuphezulu kwe-insulin, i-glycolysis iyenziwa isebenze. I-Ketogenesis ne-gluconeogeneis ziyacindezelwa.
Ukusebenza
IGlucagon, kanye nokuqamba kwayo, ihloselwe ukumisa ukuhlaselwa kanzima kwe-hypoglycemia lapho kungenakwenzeka ukuphatha glucose we-intravenous. Imiyalo yokusebenzisa i-hormone ichaza kahle yonke into ngokucacile
Lokhu kuvame ukwenzeka ezigulini ezinesifo sikashukela. Futhi, le hormone isetshenziswa ekuxilongeni ngemisebe ukuze icindezele ukunyakaza kwendlela yokugaya ukudla. Kulokhu, kunezinye izindlela ezisetshenziselwa ukusetshenziswa kwehomoni.
IGlucagon, isetshenziswa kwezokwelapha, ihlukanisiwe nama-pancreas ezingulube noma ezinkomeni. Lokhu kungenxa yokuthi ama-amino acid e-glucagon kulezi zilwane atholakale ngokulandelana okufanayo. Nge-hypoglycemia, i-hormone iphathwe ngokungaxhunyiwe ku-intramuscularly, intravenous or subcutanely ngenani le-1 mg
Ezimweni eziphuthumayo, kungcono ukusebenzisa i-glucagon kanye nemizila emibili yokuqala yokuphatha. Ngemuva kwemizuzu eyi-10, ukuthuthuka kwenzeka, okunciphisa ingozi yezifo zesistimu yezinzwa ephakathi.
I-Hyperglycemia ngaphansi kwesenzo se-glucagon ihlala isikhashana, futhi kungenzeka ingenzeki nhlobo uma izitolo ze-glycogen esibindini zinganele. Ngemuva kokushintsha lesi simo, isiguli sidinga ukudla okuthile noma senze umjovo weglucose ukuvimbela ukuhlaselwa okuphindaphindiwe kwe-hypoglycemia. Imiphumela emibi ejwayelekile yokuthola i-glucagon ukuhlanza kanye nenausea.
- Le mahomoni inqunywe ngaphambi kokwenza ucwaningo lwe-X-ray ocwaningwayo lwepheshana lesisu, ngaphambi kwe-MRI nokubuyisa umbono wokuqabula izicubu zamathumbu nesisu nokwenza umsebenzi wazo usebenze.
- I-Glucagon isetshenziselwa ukukhipha umgogodla ezifweni zomgudu we-biliary kanye ne-sphincter ye-Oddi noma ku-acute diuliculitis.
- Njengezinto ezisizayo ekususeni amatshe emgodini usebenzisa i-Dormia loop, kanye nokufakwa kwamathumbu emathunjini kanye nezinqubo ezithikamezayo esophagus nasekuthuthukiseni ukusebenza kwawo.
- I-Glucagon secretion isetshenziswa njengethuluzi lokuxilonga lokuhlola i-pheochromocytoma, ngoba yenza kusebenze ukukhishwa kwama-catecholamines ngamangqamuzana alesi simila.
- Le hormone isetshenziselwa ukwelapha ukwethuka, ngoba inomphumela we-inotropic enhliziyweni. Kuyasebenza ezigulini ezithatha i-beta-blockers, ngoba ama-adrenostimulants awasebenzi ezimweni ezinjalo.
