Comparative cytochemical and pharmacological studies on the cholinergic innervation of the branchial heart of the cephalopodSepia officinalis (L.)

Summary The dense motor innervation of the obliquely striated muscle cells in the branchial heart of Coleoida is composed of activating and inhibiting parts. The inhibiting cholinergic system investigated in this study is characterized histo- and cytochemically by a high acetylcholinesterase activity (EC 3.1.1.7) in the glycocalices of the nerve fibers with transparent synaptic vesicles, the muscle cells and, to a lesser extent, the ovoid interstitial cells, the functions of which are endocytosis and storage of catabolic substances. The pharmacological results from the isolated organ indicate a more nicotinic type of Ach-receptor, which can be reversibly blocked by D-tubocurarine and -bungarotoxin, but not with the same intensity by tetraethylammonium or atropine.