DISTRIBUTION OF RYANODINE RECEPTOR-LIKE IMMUNOREACTIVITY IN MAMMALIANCENTRAL-NERVOUS-SYSTEM IS CONSISTENT WITH ITS ROLE IN CALCIUM-INDUCEDCALCIUM RELEASE

The distributions of ryanodine receptor-like immunoreactivity and Ca A TPase-like immunoreactivity were identified in the guinea-pig and rat central nervous system using antibodies raised against the rabbit skel etal muscle ryanodine receptor and Ca ATPase. In both guinea-pig and r at cerebellum, the ryanodine receptor-like immunoreactivity was restri cted to the soma and dendrites of Purkinje cells. In the medulla, neur on somata in the hypoglossal nucleus were stained in both species, but in the dorsal motor nucleus of the vagus somata were stained in guine a-pigs but not in rats. This species difference in ryanodine receptor- like immunoreactivity is consistent with the species difference in exp ression of a ryanodine sensitive, calcium activated potassium conducta nce in neurons of the dorsal motor nucleus of the vagus. Immunoreactiv ity to Ca- ATPase was present in vagal motoneurons in both species wit h denser staining in the guinea-pig. The data further support the idea that. in neurons of the dorsal motor nucleus of the vagus, release of intracellular calcium stores via a ryanodine receptor activates a spe cific class of potassium channels, thereby modulating cell exicitabili ty.