Investigation of the Role of Potassium Channels in the Regulation of Vascular Tone in Rats

Öz

Potassium (K+) channels are important regulators of vascular tone. In this study, it was aimed to determine the effects of K+ channel types on phenylephrine-induced vascular tone. The 4 mm length vascular rings obtained from the thoracic aortas of male Wistar Albino rats were placed in the isolated tissue bath system. Vascular tension was adjusted to 1 gram. To determine the effects of K+ channel types on phenylephrine-induced vascular tone, K+ channel blockers were administered to the aortic rings after a 1-hour equilibration period. After 30 min of incubation, the vascular rings were contracted with 10-6 M phenylephrine and a stable contraction was obtained. The tension values in the periods before the phenylephrine administrations were accepted as 100%. The plateau phase tension values obtained with phenylephrine were calculated over this value. The obtained tension values were compared with the tension values in the control groups. Large-conductance calcium (Ca2+)-activated K+ channel (BKCa) blocker tetraethylammonium, intermediate-conductance Ca2+-activated K+ (IKCa) channel blocker TRAM-34, ATP-sensitive K+ (KATP) channel blocker glyburide, voltage-gated K+ (KV) channel blocker 4-Aminopyridine, and two-pore domain K+ (K2P) channel blocker anandamide administrations caused a statistically significant increase in vascular tension values. However, small-conductance Ca2+-activated K+ (SKCa) channel blocker apamin and inwardly-rectifying K+ (Kir) channel blocker barium chloride administrations did not cause a statistically significant change in vascular tension values. The findings of this study show that BKCa, IKCa, KATP, KV, and K2P channels have significant effects on the regulation of phenylephrine-induced vascular tone. On the other hand, it is suggested that SKCa and Kir channels are not important factors in the regulation of phenylephrine-induced vascular tone.

Anahtar Kelimeler

• Potassium channels
• Vascular tone
• Thoracic aort
• Tissue bath

Sıçanlarda Vasküler Tonusun Düzenlenmesinde Potasyum Kanallarının Rolünün İncelenmesi

Öz

Potasyum (K+) kanalları vasküler tonusun önemli düzenleyicileridir. Bu çalışmada K+ kanal tiplerinin fenilefrin ile uyarılan vasküler tonus üzerindeki etkilerinin belirlenmesi amaçlanmıştır. Wistar Albino ırkı erkek sıçanların torasik aortlarından elde edilen 4 mm uzunluğundaki vasküler halkalar izole organ banyosu sistemine yerleştirildi. Vasküler gerim 1 grama ayarlandı. K+ kanal tiplerinin fenilefrin ile indüklenen vasküler tonus üzerindeki etkilerini belirlemek için, 1 saatlik bir dengeleme döneminden sonra aort halkalarına K+ kanal blokörleri uygulandı. 30 dakikalık inkübasyondan sonra, vasküler halkalar 10-6 M fenilefrin ile kasıldı ve stabil bir kasılma elde edildi. Fenilefrin uygulamalarından önceki dönemlerdeki gerim değerleri %100 olarak kabul edildi. Fenilefrin ile elde edilen plato fazı gerim değerleri bu değer üzerinden hesaplandı. Elde edilen gerim değerleri kontrol gruplarındaki gerim değerleri ile karşılaştırıldı. Büyük iletkenli kalsiyum (Ca2+) ile aktive olan K+ kanal (BKCa) blokörü tetraetilamonyum, orta iletkenli Ca2+ ile aktive olan K+ kanal (IKCa) blokörü TRAM-34, ATP-duyarlı K+ kanal (KATP) blokörü gliburid, voltaj kapılı K+ kanal (KV) blokörü 4-Aminopiridin ve iki porlu K+ kanal (K2P) blokörü anandamid uygulamaları vasküler gerim değerlerinde istatistiksel olarak anlamlı artışa neden oldu. Ancak, küçük iletkenli Ca2+ ile aktive olan K+ kanal (SKCa) blokörü apamin ve içeri doğrultucu K+ kanal (Kir) blokörü baryum klorür uygulamaları vasküler gerim değerlerinde istatistiksel olarak anlamlı bir değişikliğe neden olmadı. Bu çalışmanın bulguları, BKCa, IKCa, KATP, KV ve K2P kanallarının fenilefrin ile indüklenen vasküler tonusun düzenlenmesinde önemli etkilere sahip olduğunu göstermektedir. Öte yandan SKCa ve Kir kanallarının fenilefrin ile indüklenen vasküler tonusun düzenlenmesinde önemli faktörler olmadığı düşünülmektedir.

Anahtar Kelimeler

• Potasyum kanalları
• Vasküler tonus
• Torasik aort
• Doku banyosu

Kaynakça

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