【摘要】 为研究主动脉前庭自发慢反应电位的去极离子流性质 ,利用豚鼠的离体心脏 ,常规玻璃微电极细胞内记录方法和离子通道阻断剂 ,观测最大舒张电位 (MDP)、0相除极幅度 (APA)、0相最大除极速度 (Vmax)、4相自动除极速度 (VDD)、复极 5 0 % (APD50 )和 90 % (APD90 )的时间以及自发放电频率 (RPF)。结果发现 :(1) 0 5 μmol/L尼索地平 (Nis)可使该慢电位的APA、Vmax、VDD明显减小 ,RPF减慢 ,与给药前相比P <0 0 1;(2 ) 1 2mmol/L河豚毒 (TTX)使APA和Vmax与给药前相比有所减慢 (P <0 0 5 ) ,VDD和RPF明显减慢 (P <0 0 1) ;(3) 2mmol/L 4 氨基吡啶 (4 AP)使该慢电位的MDP的绝对值、APA、Vmax减小 ,VDD和RPF加快 ,与给药前相比有显著差异 (P <0 0 1) ;(4 ) 1 5mmol/LCsCl作用 5min时 ,VDD和RPF明显降低 (P <0 0 5 ) ,10min时恢复 ;(5 )无糖低氧液灌流 15min后 ,该慢电位VDD和RPF明显减慢 (P <0 0 1)。结果表明 :(1)该区域自发慢电位 0相的主要去极离子流除Ca2 +内流外 ,还可能有少量Na+内流。 (2 ) 4相去极离子流中 ,除Ca2 +、Na+的内流和IK 衰减外 ,If 电流可能也起部分作用。更多还原

【Abstract】 Spontaneous slow action potentials of aortic vestibule of isolated guinea pig heart were intracellularlly recorded. Electrophysiological parameters examined are: maximal diastolic potential (MDP), amplitude of action potential (APA), maximal rate of depolarization of phase 0 (V max ), velocity of diastolic depolarization of phase 4 (VDD), duration of 50% and 90% repolarization (APD 50 and APD 90 ) and rate of pacemaker firing (RPF). It was found that (1) 0 5 μmol/L nisoldipine (Nis) significantly decreased APA, V max , VDD and RPF ( P <0 01); (2) 1 2 mmol/L tetrodotoxin (TTX) significantly decreased APA and V max ( P <0 05), but VDD and RPF were significantly slowed down as compared with control ( P <0 01); (3) 2 mmol/L 4 aminopyridine (4 AP) elicited a decrease in MDP, APA and V max ( P <0 01), but an increase in VDD and RPF ( P <0 01); (4) when 1 5 mmol/L CsCl was perfused for 5 min, the VDD and RPF were significantly decreased ( P <0 05); and (5) under the condition of hypoxia and perfusion with deprived glucose content for 15 min, the VDD and RPF were decreased ( P <0 01). The above results suggest that (1) in addition to Ca 2+ , Na + current contributes to generation of 0 phase of depolarization of slow response activity in aortic vestibule mainly, and (2) in addition to the inward Ca 2+ and Na + current and attenuated K + current, I f current also plays some role in phase 4 of depolarization.更多还原