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İzole sıçan aortunda dobutaminin vazokonstriktör etkisinde beta adrenerjik reseptörler rol oynar

Amaç: Alfa-1 ve beta-adrenerjik reseptörlerin, dobutaminin kardiyak etkisine aracılık ettiğine ilişkin deneysel kanıt mevcuttur. Ancak, dobutaminin vasküler etkisi ve bu etkiye beta-adrenerjik reseptörlerin katkısı belirsizliğini korumaktadır. Bu çalışma, dobutaminin sıçan aortundaki doğrudan etkisini ve bu etkide beta adrenerjik reseptörlerin rolünü araştırmayı amaçlamıştır. Gereç ve yöntem: İzole edilmiş torasik aort halkaları Krebs-Henseleit solüsyonu içeren organ banyosuna asıldı. Dinlenme periyodu sonrası, aort halkaları fenilefrinle (1 μM) kasıldıktan sonra verilen asetilkolin (10 μM) yanıtıyla endotelyal bütünlük kontrol edildi. Yıkama sonrası, dobutamin (0.001-10 μM), kümülatif konsantrasyon-yanıt eğrilerini elde etmek için organ banyosuna eklendi. Dobutaminin oluşturduğu vasküler yanıtta alfa- ve beta-adrenerjik reseptörlerin rolünü araştırmak için, bazı deneylerde, prazosin (0.0003 µM) veya propranolol (1 µM) banyo ortamına dobutaminden 30 dakika önce eklendi. Bulgular: Dobutamin, endoteli sağlam izole sıçan aortunda konsantrasyon-bağımlı kontraksiyona neden oldu. Bu etki, propranolol veya prazosin varlığında anlamlı olarak inhibe edildi (p<0.05). Ayrıca, prazosin dobutaminle elde edilen maksimum vasküler yanıtı da baskıladı (p<0.05). Sonuç: Bu sonuçlar, bildiğim kadarıyla, ilk defa endoteli sağlam izole sıçan aortunda dobutaminin vazokonstriktör etkisinde beta-adrenerjik reseptörlerin ilişkisi olduğunu göstermektedir.

Anahtar Kelimeler:

Dobutamin, alfa adrenerjik reseptör, beta adrenerjik reseptör, vazokonstriksiyon

Beta adrenergic receptors play role in the vasoconstrictor effect of dobutamine in the isolated rat aorta

Purpose: Experimental evidence exists that cardiac action of dobutamine is mediated by alfa-1 and beta- adrenergic receptors. However, uncertainty remains regarding the vascular effect of dobutamine and contribution of beta-adrenergic receptors to this effect. The aim of the present study was to investigate the direct effect of dobutamine in the rat aorta and the role of beta-adrenergic receptors in this effect. Materials and methods: The isolated thoracic aortic rings were mounted in organ bath containing Krebs-Henseleit solution. After an equilibiration period, endothelial integrity was then checked by the response to acetylcholine (10 μM) in aortic rings pre-contracted with phenylephrine (1 μM). After washout, dobutamine (0.001-10 μM) was added to generate cumulative concentration–response curves (CCRCs). To investigate the role of alfa- and beta- adrenergic receptors in the dobutamine-induced vascular response, prazosin (0.0003 µM) or propranolol (1 µM) was added to the bath medium 30 min before the addition of dobutamine in some experiments.. Results: Dobutamine produced concentration-dependent contraction in the endothelium-intact isolated rat aorta. This effect was significantly inhibited by either propranolol or prazosin (p<0.05). Prazosin also significantly supressed the maximum vascular response obtained by dobutamine (p<0.05). Conclusion: The results, to the best of my knowledge, demonstrates for the first time that beta-adrenergic receptors are involved in the vasoconstrictor effect of dobutamine in the endothelium-intact rat aorta.

Keywords:

Dobutamine, alfa adrenergic receptor, beta adrenergic receptor, vasoconstriction,

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