In vitro effects of histamine liberator compound 48/80 on rat superior cervical ganglia with special regard to the small granule-containing cells.

The effect of the histamine liberator compound 48/80 on the rat superior cervical ganglia in vitro has been investigated. After incubation of the ganglia with compound 48/80: (1) ganglionic mast cells degranulate in the same manner as in other tissues; (2) cell bodies of the postganglionic neurons are not affected by compound 48/80; (3) there is evidence that ganglionic interneurons, the monoamine-containing cells are activated. The ultrastructural aspects of this process are characterized by degranulation of perikarya and accumulation of dense core vesicles in cell processes and in terminals adjacent to presynaptic membranes. These vesicles vary in size between 200-800 A in diameter. They may represent storage sites of the neuro-transmitter complexes that have undergone exocytosis. The results are discussed with special reference to models of exocytotic processes involving the adrenergic transmitter. It is concluded that monoamine-containing cells represent interneurons in sympathetic ganglia which inhibit ganglionic transmission and which are stimulated by low concentrations of compound 48/80 in vitro.