Differential control of sympathetic drive to the rat tail artery and kidney by medullary premotor cell groups.

Sympathetic activity was recorded from the renal nerve and the ventral tail artery of anesthetized rats while neurons in three sympathetic premotor groups, the rostroventrolateral medulla (RVLM), rostroventromedial medulla (RVMM) and medullary raphe, were activated by microinjections of sodium glutamate (1-15 nl, 50 mM). RVLM activation increased renal nerve activity by 27+/-3% but caused small, inconsistent effects on the tail outflow (+15+/-10%). Raphe neuron stimulation had little effect on the renal nerve (+8+/-3%), but strongly increased tail sympathetic unit activity (+125+/-28%). RVMM neurons had little effect on either outflow. These results indicate that different premotor cell groups have different sympathetic actions. Copyright 1999 Elsevier Science B.V.