Kalp, kan ak\u0131\u015f\u0131n\u0131 ya\u015fam boyu s\u00fcrd\u00fcrebilir, dinlenme halindeyken de stres alt\u0131ndayken de\u2026 Biliminsanlar\u0131, kalp at\u0131\u015f\u0131n\u0131 kontrol etmede belirli bir iyon s\u0131n\u0131f\u0131n\u0131n rol oynad\u0131\u011f\u0131n\u0131 ke\u015ffetti.<\/p>\n
\u0130nsan kalbi, ortalama bir ya\u015fam s\u00fcresi boyunca, kesintisiz ve y\u00fcksek bir hassasiyetle \u00fc\u00e7 milyar at\u0131\u015f \u00fcretir. Bu \u00f6zellik, kalbin sa\u011f ventrik\u00fcl\u00fc (kar\u0131nc\u0131k) i\u00e7inde yer alan, sinoatriyal d\u00fc\u011f\u00fcm olarak bilinen b\u00f6lge taraf\u0131ndan sa\u011flan\u0131r. S\u00f6z konusu b\u00f6lge, kalbin atmas\u0131n\u0131 sa\u011flayan bir sarka\u00e7 olarak da nitelendirilebilir.<\/p>\n
Kalbin \u00e7al\u0131\u015fma bi\u00e7imini konu alan ara\u015ft\u0131rmalar, sinoatriyal d\u00fc\u011f\u00fcm\u00fcn de \u00f6zelle\u015fmi\u015f bir grup kalp kas\u0131 h\u00fccresinden olu\u015ftu\u011funu g\u00f6stermi\u015fti. Bu h\u00fccreler, kalbin ritmik kas\u0131lmalar\u0131n\u0131 d\u00fczenleyen elektriksel sal\u0131n\u0131mlar\u0131 olu\u015fturur. Sa\u011fl\u0131kl\u0131 yeti\u015fkinlerde kalbin at\u0131\u015f frekans\u0131 dakikada 60-80 aras\u0131nda de\u011fi\u015fmektedir. \u0130zole edilmi\u015f ve uygun ko\u015fullar alt\u0131na al\u0131nm\u0131\u015f bir kalp, bedenin d\u0131\u015f\u0131nda da sabit bir at\u0131m h\u0131z\u0131nda \u00e7al\u0131\u015fmaya devam eder. Bu i\u015flev, sempatik ve parasempatik sinirler olarak bilinen iki ayr\u0131 alt sisteme sahip olan otonom sinir sistemi taraf\u0131ndan ger\u00e7ekle\u015ftirilir.<\/p>\n
Peki, kalbin at\u0131m h\u0131z\u0131 nas\u0131l d\u00fczenlenir, bu mekanizma nas\u0131l \u00e7al\u0131\u015f\u0131r? Biliminsanlar\u0131, onlarca y\u0131ld\u0131r sinoatriyal d\u00fc\u011f\u00fcm\u00fc olu\u015fturan h\u00fccrelerdeki \u00f6zel iyon kanallar\u0131n\u0131n s\u00fcrece d\u00e2hil oldu\u011funu d\u00fc\u015f\u00fcn\u00fcyordu. Protein yap\u0131l\u0131 olan iyon kanallar\u0131, biyolojik zarlara (membranlara) g\u00f6m\u00fcl\u00fcd\u00fcr ve elektrik y\u00fckl\u00fc atomlar\u0131n membrandan ge\u00e7i\u015fini d\u00fczenlerler. Bu sebeple iyon kanallar\u0131, sinirsel uyart\u0131lar\u0131n olu\u015fmas\u0131nda ve kaslar\u0131n kas\u0131lmas\u0131nda b\u00fcy\u00fck bir role sahiptir. Kalp at\u0131\u015f\u0131n\u0131 kontrol etti\u011fi d\u00fc\u015f\u00fcn\u00fclen iyon kanallar\u0131, \u201cHCN kanallar\u0131\u201d olarak adland\u0131r\u0131l\u0131r. Sinoatriyal d\u00fc\u011f\u00fcm \u00fczerinde bu iyon kanallar\u0131n\u0131n HCN1, HCN2 ve HCN4 isimli \u00fc\u00e7 alt tipi bulunur. HCN kanallar\u0131 h\u00fccre zar\u0131 boyunca voltajda meydana gelen hiperpolarizasyona yan\u0131t olarak sinoatriyal d\u00fc\u011f\u00fcm h\u00fccrelerinde cAMP ad\u0131 verilen bir sinyal molek\u00fcl\u00fcn\u00fc etkinle\u015ftirir. Konuya geleneksel bak\u0131\u015f, cAMP\u2019nin HCN4 kanal\u0131na etki etmesiyle kalp h\u0131z\u0131nda art\u0131\u015f meydana geldi\u011fini ortaya koymaktad\u0131r.<\/p>\n
HCN kanallar\u0131n\u0131n rol\u00fc i\u00e7in yukar\u0131da anlat\u0131lan model uygun gibi g\u00f6r\u00fclse de, biyolojik sistemler \u00fczerinden do\u011frulama yap\u0131lmas\u0131n\u0131n zor oldu\u011fu ifade edilmektedir. Yeni \u00e7al\u0131\u015fmada biliminsanlar\u0131 fareleri kullanarak deneyler yapt\u0131. Farelerde HCN4 kanal\u0131n\u0131n i\u015flevini d\u00fczenleyen gen, HCN4 ile cAMP aras\u0131ndaki ili\u015fkiyi kesecek \u015fekilde mutasyona u\u011frat\u0131ld\u0131, b\u00f6ylelikle HCN4 iyon kanal\u0131 otonom sinir sisteminden gelen sinyallere yan\u0131t veremez hale getirildi. Mutasyonun ard\u0131ndan farelerde kalp h\u0131z\u0131n\u0131n \u00e7ok d\u00fc\u015f\u00fck seyretti\u011fi ve ayr\u0131ca kalp at\u0131\u015f\u0131n\u0131n d\u00fczenini yitirdi\u011fi g\u00f6r\u00fcld\u00fc. Bununla birlikte farelerde, HCN4 iyon kanal\u0131 cAMP\u2019yi ba\u011flayamamas\u0131na ra\u011fmen kalbin kas\u0131lma mekanizmas\u0131 d\u00fczenlenebiliyordu. B\u00f6ylelikle bu iyon kanal\u0131n\u0131n kalp at\u0131\u015f h\u0131z\u0131n\u0131n d\u00fczenlenmesindeki \u00f6nemli rol\u00fc i\u00e7in sunulan hipotezin yanl\u0131\u015flanabildi\u011fini belirten ara\u015ft\u0131rmac\u0131lar, deneylerinin HCN4’\u00fcn sinir sisteminden gelen sinyallerle olu\u015fan a\u015f\u0131r\u0131 miktardaki reaksiyonu d\u00fczenleyerek kalp ritmini sabit tutmay\u0131 sa\u011flad\u0131\u011f\u0131n\u0131 ve esas bu i\u015flevin son derece \u00f6nemli oldu\u011funu belirtiyorlar. Yeni \u00e7al\u0131\u015fma odakland\u0131\u011f\u0131 temel ara\u015ft\u0131rma alan\u0131n\u0131n \u00f6tesinde \u00e7ok b\u00fcy\u00fck bir \u00f6neme sahiptir ve gelecekte kalp hastal\u0131klar\u0131n\u0131n tedavisinde ciddi bir etkiye sahip olaca\u011f\u0131 d\u00fc\u015f\u00fcn\u00fclmektedir.<\/p>\n
Kaynak:<\/strong> https:\/\/medicalxpress.com\/news\/2020-11-heartbeat.html<\/p>\n","protected":false},"excerpt":{"rendered":" Kalp, kan ak\u0131\u015f\u0131n\u0131 ya\u015fam boyu s\u00fcrd\u00fcrebilir, dinlenme halindeyken de stres alt\u0131ndayken de\u2026 Biliminsanlar\u0131, kalp at\u0131\u015f\u0131n\u0131 kontrol etmede belirli bir iyon s\u0131n\u0131f\u0131n\u0131n rol oynad\u0131\u011f\u0131n\u0131 ke\u015ffetti. \u0130nsan kalbi, ortalama bir ya\u015fam s\u00fcresi boyunca, kesintisiz ve y\u00fcksek bir hassasiyetle \u00fc\u00e7 milyar at\u0131\u015f \u00fcretir. Bu \u00f6zellik, kalbin sa\u011f ventrik\u00fcl\u00fc (kar\u0131nc\u0131k) i\u00e7inde yer alan, sinoatriyal d\u00fc\u011f\u00fcm olarak bilinen b\u00f6lge taraf\u0131ndan […]<\/p>\n","protected":false},"author":1390,"featured_media":47078,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[19],"tags":[431,1631,7083,7082],"class_list":["post-47077","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-bilim-gundemi","tag-gen","tag-hastalik","tag-iyon-kanali","tag-kalp-ritmi"],"acf":[],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t