Effects of dexmedetomidine on rabbit sinus node and atrioventricular node / 临床麻醉学杂志

ABSTRACT

Objective To investigate the effects of different doses of dexmedetomidine(Dex) on rabbit sinus node and atrioventricular node.Methods A total of 24 healthy male rabbits weighing 1.5-2.8 kg,were divided into 3 groups randomly according to random number table (n =8).Group C (control),critical dosage of Dex causing sinus bradycardia D1 (loading dose of Dex was 10 μg/kg, continual pumping dose was 5 μg · kg-1 · h-1 ),six times of critical dosage of Dex causing sinus bradycardia D2 (loading dose of Dex was 60 μg/kg,continual pumping dose was 30 μg·kg-1 ·h-1 ). Rabbits were anesthetized,the right femoral artery was separated and catheterized followed by real-time monitoring of arterial blood pressure.Right external jugular vein was searched and separated,bi-polar stimulating electrode were inserted to the junction of superior vena cava and right atrium,the index of sinus node and atrioventricular node were observed by means of programmed stimulation.Si-nus node recovery time (SNRT),corrected sinus node recovery time (CSNRT),total recovery time (TRT),and atrioventricular node 2∶1 point were recorded before Dex infusion (T0 ),1 5-20 min after infusion of Dex (T1 )and 50-60 min after perfusion of Dex (T2 ).Results SNRT,CSNRT,TRT and 2∶1 point had no statistical significance.Compared with T0 ,SNRT,CSNRT and CSNRT were signifi-cantly prolonged at T1 and T2 .2∶1 point in group D1 and D2 was shortened obviously at T1 than that at T2 (P <0.05).SNRT,CSNRT and TRT of group D1 at T2 were significantly prolonged,2∶1 piont was shortened compared with T1 (P <0.05).SNRT,CSNRT and TRT of group D1 and D2 were pro-longed both at T1 and T2 than those of group C.2∶1 point was shortened in group D1 and D2 at T1 than that in group C (P <0.05).Compared with group D1,SNRT,CSNRT and TRT of group D2 at T1 and T2 were prolonged,2∶1 point was shortened obviously (P <0.05).Conclusion Load capacity of 10 μg/kg Dex apparently inhibits the function of rabbit sinus node and atrioventricular node,which is partially recovered within a short time (≤ 1 h).The inhibiting effect is more continously and re-markably in load capacity of 60 μg/kg Dex.