A FURTHER STUDY OF REFLEX CHANGES OF BLOOD PRESSURE IN COMPLETELY SYMPATHECTOMIZED ANIMALS

Abstract

The blood-pressure reactions to afferent stimulation of several nerves. to occlusion of the carotids, to asphyxia, and to struggle were studied in completely sympathectomized and vagotomized cats and dogs. Reflex rises and falls of blood pressure were obtained in the two species on stimulation of afferent nerves. Exclusion of the splanchnic vascular area did not abolish these responses. No significant reflex rises of blood pressure were obtained on occlusion of the innervated carotids in either cats or dogs. Struggle is attended by a sharp severe fall of blood pressure in cat9 but not in dogs. This was the only difference detected between the 2 species. The mechanism of these reactions is discussed. They are at least partly controlled by non-sympathetic vasomotor nerves and these nerves are probably the dorsal root dilators.