Adrenergic innervation of coronary arteries and ventricular myocardium in the pig: fluorescence microscopic appearance in the normal state and after ischemia.

A fluorescence histochemical study was performed to describe the adrenergic innervation of the coronary arteries and the left ventricular myocardium in the pig. Large bundles of adrenergic nerve fibres were almost exclusively found running along the large coronary arteries. The arteries usually show a dense innervation of the vessel wall, evenly distributed throughout the adventitia in the larger arteries and more concentrated to the adventitia-medial border in the smaller arteries and arterioles. Most parts of the left ventricular myocardium showed a dense adrenergic innervation, however, a moderate dense and in some areas even sparse innervation was observed towards the apex of the left ventricle. Following 10 or 20 min of ischemia a small reduction in fluorescence intensity was observed in 2 out of 6 hearts. In 4 of the hearts other changes of the appearance of the adrenergic terminals were found, e.g., an unsharp, spread-out or interrupted appearance.