Abstract
(1) The stimulation of the medial and midline nuclei groups in the thalamus and most of the hypothalamic and subthalamic nuclei resulted in an increase in blood pressure and a decrease in renal blood flow which was attributed to renal vasoconstriction caused by both neural factors and humoral ones, especially adrenaline.
(2) The stimulation of a part of medial, midlinc, ventral and lateral nuclei groups in the thalamus, the preoptic area and a part of anterior and middle portions in the hypothalamus caused a fall in blood pressure associated with a decrease in renal blood flow. The latter might be due in part to a decrease in cardiac output.
(3) On stimulation of the geniculate bodies and the ventral and lateral nuclei groups, there often occurred little or no circulatory changes.
(4) In order to induce more pronounced parasympathetic reactions, the diencephalon was stimulated after the sympathetic blocking agents such as hydergine® or guanethidine were administered intravenously, but it was not successful. There were no evidences that suggested the presence of renal vasodilator nerve in the diencephalon.
(5) Type A response induced by the electrical stimulation of dog's diencephalon was modified by guanethidine; there was frequently marked inhibition of immediate responses consequent to the stimulation or a delay in the onset of responses. This response was not nearly affected by reserpine and 1-hydrazinophthalazine.
