Sibel KÖKTÜRK, İsmail SEÇKİN, Bülent URULUER, Güngör ŞATIROĞLU, Mümin UZUNALAN, Meltem KURUŞ

Solunumsal asidozlu sıçanlarda böbrek kortikal toplayıcı kanal interkalate hücrelerdeki ultrastürüktürel değişiklikler

Kortikal toplayıcı kanallar asit/baz homeos-tazisinin düzenlenmesinde önemli rol oynar. Bu kanallar esas hücreler yanında interkalate hücrelerin A (AICH) ve B (BICH) olmak üzere iki tipini ihtiva etmektedirler. Yakın yıllarda yapılan çalışmalar AICH'ların karbonik anhid-razdan zengin olup, apikal plazma membran-lannda ve apikal sitoplazmik veziküllerinde vakuoler H+-ATPaz ve bir bazolateral değişim¬ciye sahip olup H+ sekresyonu ve HCO3" reap-sorbsiyonu yaptığını, BICH'ların ise yine kar¬bonik anhidrazdan zengin olup, apikal memb-randa CI" / HCO3" değişimci ile bir bazolateral H+-ATPaz ye sahip olduğu ve H+reapsorbsiyo-nu ve HCO3" sekresyonu ile ilgili olduğunu göstermektedir. Bizde yapmış olduğumuz bu çalışmada Wistar sıçanlara 12 saat ve 24 saat süreyle özel bir fanus içerisinde %10 CO2 solutularak oluşturduğumuz solunuma bağlı asi-doziste bu farklı hücrelerin asidozis işleminde-ki farklı rollerini laboratuvar bulguları ışığında 'ultrastrüktürel düzeyde göstermeyi amaçladık. Bu gruplarda ürin pH'sı giderek azalırken, plazmada , HCO3" düzeyinde ve K+'da artma ve CF'de giderek azalma saptadık. Ultrastrüktürel tetkiklerde ise, AICH'da her iki grupta da apikal sitoplazmada tubulo vesiküllerin sayısında giderek azalma ile birlikte mitokondri ve apikal hücre mikrovilluslarında giderek artma ve boyca da azalma görüldü. BICH'larda ise 12 saatlik grupta fazlaca değişiklik gözlenmedi. 24 saatlik grupta ise artan mitokondri yoğunluğuyla birlikte bazolateral bölgeden apikal yüzeye doğru yönlenmiş bir vesikül trafiği gözlendi.Bulgularımız bize oluşturduğumuz solunu¬ma bağlı asidozda A-ICH'ların esas etkili hüc¬reler olduğunu ve asidozun kronik dönemlerinde (24 saat) B-ICH'lann AICH'lara benzer fonksiyonel karakterler (H+ sekresyonu) kazan¬mak üzere morfolojik dönüşüme uğradığı dü¬şündürmektedir.

Ultrastructural changes of respiratory acidosis in rat cortial collecting tubule intercalated cells

Recent studies on cortical collecting tubules have supported that type- A intercalated cells have a H+-ATPase in apical membrane and a Cl- / HCO3- exchanger in basolateral membrane and thus secrete H+ and reabsorb HCO3-while type- B intercalated cells have a Cl- / HCO3- exchanger in apical membrane and a H+-ATPase in basolateral membrane and thus they secrete HCO3 - and reabsorb H+. In our study we aimed to investigate the ultrastuructural changes in different intercalated cells in cortical collecting tubules of rats kidney with 12 and 24 hours respiratory acidosis. Results.- In the type A intercalated cells of rats with 12 and 24 hours respiratory acidosis, apical tubulo vesicles decreased in number while mitocondria, number and length of microvilli increased. In type B intercalated cells of 12 hours respiratory acidosis group there were no prominent ultrastuructural changes. However, in 24 hours respiratory acidosis group, we observed an increased traffic of vesicles to words the apical pole of type B intercalated cells. Mitochondrial density was also increased. Conclusion.- Our finding on the type A intercalated cells have supported the previous studies while the finding on type B intercalated cells were contraversial. As a conclusion we thought that type B intercalated cells showed morphological alterations reflecting changes in functional characteristic in response to chronic respiratory acidosis (24 hours), in addition to ultrastuructural changes in type A intercalated cells.

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