Nonuniformity of sympathetic nerve activity to the skin and kidney.

NINOMIYA, ISHIO, AYA IRISAWA, AND NAOKO NISIMARU. Nonuniformity of sympathetic nerve activity to the skin and kidney. Am. J. Physiol. 224(Z) : 256-264. 1973.-The effects of baroceptor reflex on the sympathetic nerve activity (SNA) to the skin and kidney were compared in anesthetized cats. Grouped SNA synchronous with cardiac cycle and respiration was not the major pattern in the skin nerve. With increase in mean aortic pressure from 111 to 183 mm Hg at room temperature of 22-27 C, SNA to the skin was reduced to 88% of the control level, whereas SNA to the kidney decreased to the noise level. When the skin was cooled bv bath water of 10-l 5 C, baroceptor-independent SNA to the skin increased above the precooling level, whereas baroceptor-dependent SNA to the kidney varied, depending on two inputs. Inhibitory effects of sodium pentobarbital on SNA to the skin were greater than those on SNA to the kidney. In both the skin and renal nerves, the mean diameter of the unmyelinated fibers was 0.75 and 0.64 p, respectively. SNA to the skin and kidney was inhibited by hexamethonium bromide (ganglion blockade). It is concluded that both the skin and renal nerve activities are postganglionic sympathetic discharges, but the major parts of the skin nerve activity controlling skin temperature are composed of baroceptorindependent components, whereas those of the renal nerve activity are made up of baroceptor-dependent components.