Harrison Theresa A, Perry Kristi M, Hoover Donald B
Department of Anatomy and Cell Biology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA.
Anat Rec A Discov Mol Cell Evol Biol. 2005 Aug;285(2):758-70. doi: 10.1002/ar.a.20213.
Our purpose was to identify and localize intrinsic cardiac ganglia innervating distinct regions of the heart using postmortem tracing of nerve projections with DiI, a method not previously used to study the intrinsic cardiac nervous system. We also investigated the possibility of collateral innervation of myocardium and intrinsic ganglia. In isolated paraformaldehyde-fixed guinea pig hearts, crystals of DiI (1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate) were inserted into the posterior ventricular myocardium below the atrioventricular groove, the right atrium, or the left ventricular septum. Hearts were placed in the dark at 37 degrees C for 2-14 weeks to allow DiI diffusion within neuronal membranes. Labeled neurons were observed in intracardiac ganglia after at least 4 weeks of dye exposure. Labeling was restricted to the inferior-most ganglia (those near the atrioventricular groove) when DiI was inserted into the posterior ventricular myocardium and to ganglia near the sinus node after right atrial DiI placement. Application of DiI to the left ventricular septum resulted in neuron labeling in ganglia primarily in the interatrial septum near the atrioventricular node. After 8 weeks, DiI-labeled nerve fibers and varicosities were seen surrounding unlabeled neurons in some ganglia, suggesting that axons terminating in or passing through the DiI application site in posterior ventricular tissue had collateral branches innervating these ganglia. These results indicate that intrinsic innervation of major cardiac subdivisions is accomplished by regionally segregated cardiac ganglia. Also, tracing with DiI has provided evidence for collateral nerve projections that could be the substrate for novel intracardiac regulatory circuits.
我们的目的是使用DiI对神经投射进行死后追踪，以识别和定位支配心脏不同区域的心脏固有神经节，这是一种以前未用于研究心脏固有神经系统的方法。我们还研究了心肌和固有神经节侧支神经支配的可能性。在分离的经多聚甲醛固定的豚鼠心脏中，将DiI（1,1'-二辛基-3,3,3',3'-四甲基吲哚羰花青高氯酸盐）晶体插入房室沟下方的后心室心肌、右心房或左心室间隔。将心脏置于37摄氏度的黑暗环境中2至14周，以使DiI在神经元膜内扩散。在染料暴露至少4周后，在心脏内神经节中观察到标记的神经元。当将DiI插入后心室心肌时，标记仅限于最下方的神经节（靠近房室沟的那些神经节），而在右心房放置DiI后，标记仅限于窦房结附近的神经节。将DiI应用于左心室间隔导致主要在房室结附近的房间隔中的神经节中的神经元标记。8周后，在一些神经节中可见DiI标记的神经纤维和曲张体围绕未标记的神经元，这表明终止于后心室组织中DiI应用部位或穿过该部位的轴突具有支配这些神经节的侧支。这些结果表明，心脏主要分区的固有神经支配是由区域分隔的心脏神经节完成的。此外，用DiI进行追踪为侧支神经投射提供了证据，这些投射可能是新型心脏内调节回路的基础。
