窦性节律下家兔心率与在位心室肌纤维有效不应期的关系

在自然呼吸和窦性节律下,用浮置式玻璃微电极引导在体单个左心室肌纤维动作电位,作为兴奋的指标,以其 0相触发产生期前的试验刺激,测定有效不应期(ERP)。38只家兔的测定结果表明,在R-R间期为205—330ms的范围内,随着心率加快(R-R间期缩短),ERP减小,而 ERP/RR 间期增大,说明 ERP 与心率直接有关。并且,在较快的心率时,ERP 相对延长。通过相关与回归分析,制出了能够删除心率影响的校正公式。静脉注射酒石酸锑钾(50mg/kg)发现,在窦性和起搏节律下,酒石酸锑钾均能轻度延长 ERP(P<0.001)。窦性节律下的校正后值与起搏节律的测定结果完全一致。证明校正后值能够用来比较处理前后不同心率条件下,各种药物、离子及其它因素对ERP 的影响。 本文的校正公式虽然只适用于同种动物和方法,但此校正公式的制作原理也可以广泛应用到其它多种动物。

RELATIONSHIP BETWEEN HEART RATE AND THE EFFECTIVE REFRACTORY PERIOD OF VENTRICULAR CELLS.OF RABBIT AT SINUS RHYTHM IN SITU

The effective refractory period (EKP)of left ventricular cells of 38 albinorabbits at various heart rates during natural breathing were determined. The phase 0of the transmembrane action potential (TAP) that was recorded with floating glassmicroelectrode was used to trigger the stimulating circuit. TAP was used as theindicator of excitation. Through statistical analysis of the data of 134 units, quanti-tative relationship between heart rate and ERP was evaluated when the sinuscycle lengths (RR interval) were in the range of 205-330 ms and regression equa-tion was obtained by linear regression. The correction formula that can eliminatethe effect of heart rate on ERP was also worked out. Significant prolongation(P<0.001) of (ERP) was induced by the antinomy potassium tartrate (APT, 50mg/kg, i.v.) during sinus rhythm (7.8%) and when cycle length was held cons-tant at 260 ms by ventricular pacing (7.5%). The results of corrected ERP at sinusrhythm are constant with the results of pacing rhythm which indicate that thecorrection formula is very useful. The ratio ERP/RR interval was greater atshorter cycle lengths indicating that a larger fraction of the cycle was refractory atfaster heart rates. Th ratio ERP/APD_(90) and ERP/QT remain constant in therange of sinus cycle lengths studied.