Hülagü BARIŞKANER, Halil İbrahim KARABACAK, Ekrem ÇİÇEK

Tavşan torasik aortasında adenozin ve guanozinin gevşeme cevapları üzerine L-NAME (NG-nitro L-arginin metil ester) 'in etkileri

Amaç: Bu invitro çalışmada endotelli ve endotelsiz tavşan torasik aortasında noradrenalin (NA) ile kasılan dokuda adenozin ve guanozinin yaptığı gevşeme cevaplarına NG-nitro L-arginin metil esterin (L-NAME) etkisi araştırılmıştır. Yöntem: Endotelli ve endotelsiz tavşan torasik aortalarına adenozin ve guanozin kümülatif konsantrasyonlarda uygulandı. Adenozin ve guanozinin oluşturduğu gevşemeye L-NAME ilave edildi. Bulgular: ($10^{-5}$ M NA endotelli ve endotelsiz dokuda kasılma oluşturdu. Endotelli dokuda 10"6 M indometasin varlığında, kümülatif tarzda ilave edilen adenozin ve guanozin ( ($10^{-9}$ - $10^{x-4}$ M) doza bağımlı olarak gevşeme cevapları oluşturdu. Elde edilen maksimum gevşeme yüzdeleri sırasıyla % 93.8±3.3, % 83.7+5.5 olarak bulundu. Ortama ($10^{-6}$ M ilave edildiğinde ise adenozin ve guanozin ile oluşan maksimum gevşeme yüzdeleri sırasıyla % 71.0+8.0, %74.0 ± 6.9 olarak bulunmuştur. L-NAME adenozin cevabını anlamlı olarak azalttı. Endotelsiz dokuda kümülatif tarzda ilave edilen adenozin ve guanozin doza bağımlı olarak gevşeme cevapları oluşturdu. Elde edilen maksimum gevşeme yüzdeleri sırasıyla % 70.5+8.6, % 66.7±7.2 olarak bulundu. Sonuç: Adenozine bağlı gevşeme cevabının oluşumuna kısmen nitrik oksit salıverilmesinin aracılık ettiğini, buna karşın guanozin cevaplarında bu mekanizmanın rolünün bulunmadığı söylenebilir.

Anahtar Kelimeler:

Tavşanlar, Modeller, hayvan, Adenozin, Aort, torasik, Doz-yanıt ilişkisi, ilaç, Gevşeme

Effects of L-NAME on the relaxations induced by adenosine and guanosine in the rabbit thoracic aorta

Objective: The aim of this in vitro study was to investigate the effects of L-NAME on adenosine and guanosine induced relaxations in noradrenaline (NA) precontracted rabbit thoracic aorta with or without endothelium. Methods: Adenosine ($10^{-9}$ - $10^{x-4}$ M) and guanosine ( ($10^{-9}$ - $10^{x-4}$ M) were used in the rabbit thoracic aorta with or without endothelium. L-NAME was added on adenosine and guanosine induced relaxation. Results: ($10^{-5}$ M NA caused contraction in tissues with or without endothelium. in the presence of ($10^{-6}$ M indomethacin, adenosine and guanosine produced relaxation in a concentration-dependent manner in the tissue with endothelium. Mean maximal relaxant percentages to adenosine and guanosine were 93.8± 3.3% and 83.7±5.5%, respectively. in the presence of ($10^{-6}$ M L-NAME, mean maximal relaxant responses to adenosine and guanosine were 71.0±8.0 and 74.0±6.9% respectively. Adenosine responses were significantly reduced by L-NAME. Adenosine and guanosine produced relaxations in a concentration-dependent manner in the tissue without endothelium. Mean maximal relaxant responses to adenosine and guanosine were 70.5±8.6%, 66.7±7.2% respectively. Conclusion: These results suggest that relaxant response of adenosine is partly related to nitric oxide release, however this mechanism may not play a functional role in guanosine responses.

Keywords:

Rabbits, Models, Animal, Adenosine, Aorta, Thoracic, Dose-Response Relationship, Drug, Relaxation,

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