Prosheva Valentina, Vityazev Vladimir, Lebedeva Elena
Institute of Physiology, Кomi Science Centre, Ural Branch of the Russian Academy of Sciences, 50 Pervomayskaya Street, 167982, Syktyvkar, Russia.
J Comp Physiol B. 2025 Apr;195(2):181-190. doi: 10.1007/s00360-025-01612-5. Epub 2025 Mar 28.
Pacemaker atrioventricular (AV) rings, continuous with the AV node, have been shown to be present in the mammalian and avian hearts. There is conspicuous lack of electrophysiological data on the cardiac pacemakers in reptiles. We aimed to characterize the AV ring in the common lizard heart for the first time using conventional microelectrode technique. Detaching the sinoatrial (SA) area unmasked pacemaking in the AV junction. In all seven studied isolated AV ring preparations, we could record action potentials (APs) with characteristic diastolic depolarization, with a slow upstroke (dV/dt ) of 3.5 ± 0.3 V s and a low amplitude of 57.8 ± 1.3 mV. The cells with pacemaking potentiality were found to surround the atrial orifice of the right AV valve. We identified some commonalities between phenotype of right AV ring pacemaker APs and SA dominant pacemaker ones. Thus, the AV ring in the reptile heart demonstrates pacemaking activity and contains cells that resemble the electrophysiological characteristics of mammalian and avian pacemaker myocytes in AV rings surrounded the atrial orifices of AV valves.
与房室结相连的房室（AV）环已被证明存在于哺乳动物和鸟类的心脏中。然而，关于爬行动物心脏起搏器的电生理数据明显缺乏。我们旨在首次使用传统微电极技术对普通蜥蜴心脏的房室环进行表征。分离窦房（SA）区域可揭示房室交界处的起搏功能。在所有七个研究的离体房室环标本中，我们能够记录到具有特征性舒张期去极化的动作电位（APs），其上升缓慢（dV/dt）为3.5±0.3 V/s，幅度较低，为57.8±1.3 mV。发现具有起搏潜力的细胞围绕右房室瓣的心房开口。我们确定右房室环起搏器APs的表型与窦房主导起搏器的表型之间存在一些共性。因此，爬行动物心脏中的房室环表现出起搏活动，并且包含在围绕房室瓣心房开口的房室环中类似于哺乳动物和鸟类起搏心肌细胞电生理特征的细胞。
