Hardie E L, Jones S B, Euler D E, Fishman D L, Randall W C
Am J Physiol. 1981 Jul;241(1):H45-53. doi: 10.1152/ajpheart.1981.241.1.H45.
The sinoatrial node (SAN) artery (SANA) was cannulated in dogs anesthetized with chloralose (7 dogs) or pentobarbital (1 dog). Intra-SANA injection of acetylcholine (ACh) with edrophonium (EPh) produced a transient junctional rhythm (JR) when the cannula tip lay near SANA origin. However, when ACh-EPh was injected while the cannula tip lay within SAN region, a slower P wave rhythm, rather than a JR, developed. To determine visually the injected ACh-EPh distribution, an equal volume of dye was injected under similar conditions. Dye-distribution patterns were consistent in all atria. These averaged 44 +/- 2% of the total endocardial surface, indicating that SANA distribution is not discrete, but widespread. Dye extended cranially, caudally, and laterally and included documented subsidiary pacemaker sites. Dye approached, but never trespassed, the coronary sinus ostium. Results suggest that cholinergic drug injection into the proximal SANA may suppress not only the SAN, but subsidiary atrial pacemakers as well. In this situation, junctional pacemakers probably emerge, not because of inherently greater automaticity, but after default of subsidiary atrial pacemakers.
在使用水合氯醛麻醉的犬（7只）或戊巴比妥麻醉的犬（1只）中，对窦房结（SAN）动脉（SANA）进行插管。当插管尖端位于SANA起始部位附近时，向SANA内注射乙酰胆碱（ACh）和依酚氯铵（EPh）会产生短暂的交界性心律（JR）。然而，当插管尖端位于SAN区域内注射ACh-EPh时，会出现较慢的P波节律，而非JR。为了直观地确定注射的ACh-EPh分布情况，在类似条件下注射等量的染料。染料分布模式在所有心房中均一致。这些染料平均占心内膜总面积的44±2%，表明SANA分布并非离散的，而是广泛的。染料向头侧、尾侧和外侧延伸，包括已记录的次级起搏点。染料接近但从未越过冠状窦口。结果表明，向近端SANA注射胆碱能药物不仅可能抑制SAN，还可能抑制心房次级起搏器。在这种情况下，交界性起搏器的出现可能并非因其固有更高的自律性，而是在心房次级起搏器功能缺失之后。
