I propose to investigate the effects of venom from the scorpion, Centuroides sculpturatus, on vascular chemoreceptive control of breathing in the cat. Chemoreceptors, specifically the aortic and carotid bodies, have been implicated as sites which reflexively generate apnea or rapid and gasping breathing when stimulated by this venom. I hope to relate such breathing impairments to the action of venom on these sites as well as on those of the pulmonary circulation and on the central breathing control centers. In the process I shall record afferent nerve traffic to support my theory that venom causes excitatory changes for the thoracic and carotid chemoreceptors. As another aspect of this proposal, I shall test the hypothesis that, like other Buthid venoms, this venom contains separate components toxic to mammals (mice) and to insect larvae (blowflies). Should this be established I will test the chemical factors to determine which stimulates the vascular chemoreceptors. I intend to obtain venom fractions by techniques which have been used successfully elsewhere (gel electrophoresis) to separate other scorpion venoms into parts toxic to insect larvae and mice. I expect to obtain additional information about the effects of this venom and its individual components on the skeletal muscle, autonomic, and cardiovascular systems of cats.