Neuroanatomy and immunohistochemistry of cardiac ventricles in rabbit (543.2)

Abstract

Rabbit model is used in cardiac electrophysiology but neuroanatomy of the rabbit heart (RH) is poorly examined. We aimed to ascertain the architecture of intrinsic cardiac nerve plexus of the RH, and the neurochemical phenotypes of ventricular nerves (VNs) and nerve fibers (NFs) using histochemical acetylcholinesterase staining and immunofluorescent labeling for PGP 9.5, TH, ChAT, nNOS, and SP in 18 New Zealand white rabbits. Cardiac nerves (CNs) accessed ventricles of the RH by the left and middle dorsal and the right and left coronary subplexuses. In the rabbit ventricular walls, there were found TH, ChAT, nNOS and SP positive (+) NFs. In VNs, more than 65% of NFs were TH(+), while only 7% were cholinergic ones. On the average, 4% of nNOS(+) and SP(+) NFs were found in VNs. The TH(+) NFs also predominated in the interventricular septum, papillary muscles, and in perivascular nerves. The PGP9.5(+) NFs distributed within the myocardium occupied 4.2% in the left ventricle and 3.8% in the right one. The mean area of NFs in papillary muscle were 2.6% for TH(+), 2.4% for ChAT(+), 1.4% for SP(+) and 0.6% for nNOS(+). Endocardial nerves contained 15.8% TH(+), 6.3% SP(+), 4.2% ChAT(+), and 1.5% nNOS(+) NFs. In summary, the RH corresponds neuroanatomically to hearts of some rodents, but it’s noticeably distinct from the human one.Grant Funding Source: MIP‐031/2013 from the Research Council of Lithuania