Vinogradova T M, Bogdanova E A, Sukhova G S, Udel'nov M G
Biull Eksp Biol Med. 1982 Oct;94(10):7-10.
Variations in the sinus node rate of the frog heart isolated together with the atria were studied during suprathreshold atrial stimulation at a frequency exceeding the intrinsic sinus node rate. If the stimulation frequency surpassed the intrinsic sinus node rate by 20%, the sinus node rate became equal to the pacing rate. Provided the pacing rate was increased, the sinus node rhythm became irregular. If the pacing rate exceeded the sinus node rate more than two-fold, the latter became half the pacing rate. Variations in the sinus node rate during suprathreshold atrial stimulation were also observed after blockade of possible retrograde conduction by application of the necrotic tissue on the sinoatrial border. The results allow the conclusion that variations in the sinus node rate seen during high-frequency suprathreshold atrial stimulation are not connected with retrograde conduction.
在高于阈值的心房刺激下，对与心房一起分离出的蛙心窦房结速率变化进行了研究，刺激频率超过了固有窦房结速率。如果刺激频率比固有窦房结速率高出20%，窦房结速率就会与起搏速率相等。如果起搏速率增加，窦房结节律就会变得不规则。如果起搏速率超过窦房结速率两倍以上，后者就会变为起搏速率的一半。在用坏死组织作用于窦房边界以阻断可能的逆向传导后，也观察到了高于阈值的心房刺激期间窦房结速率的变化。这些结果可以得出结论，高频高于阈值的心房刺激期间观察到的窦房结速率变化与逆向传导无关。
