Comparative study of innervation of cardiac ventricles in the mouse and rat

Abstract

Intrinsic cardiac nervous system, in addition to the conductive system, takes a key role in regulation of the heart rate. The smaller an animal is, the faster its heart beats. We hypothesized that there is the relationship between the heart rate and the innervation in the cardiac ventricles. Two laboratory animals, the mouse and the rat, which differ both in their size and the heart rate, were chosen to investigate comparing the innervation of cardiac ventricles in these species. This study includes 2 mouse and 2 rat hearts examined. Transverse sections of cardiac ventricles were stained immunohistochemically for protein gene product 9.5 (PGP 9.5), tyrosine hydroxylase (TH), calcitonin gene-related peptide (CGRP) and substance P (SP) in order to reveal general, sympathetic, and sensory neuronal fibres, respectively. Preparations were analysed using a fluorescence microscope AxioImager Z1. Positively stained neural structures of the cardiac walls were quantitatively explored by calculating the area, nerve fibres (NFs) composition and innervation density. [...].