Evidence for descending tonic inhibition specifically affectingsympathetic pathways to kidney

Kristen Hayes, Christopher P. Yardley and Lynne Weaver Journal of physiology 1991 434 295-306 This is an early study investing whether the RVLM provides tonic inhibitory control over different sympathetic nerves. Specifically splenic , renal, splanchnic and the nerves comming from the T13 region. We know that the RVLM is important for the tonic control of blood pressure and that when stimulated with glu there is an in increase in nerve activity and bp. This study aimed to to test whether blocade of excitory neurons in the RVLM leads to an imbalance and profound infuence of inhibitory stimuli that could be balanced could counter acted by spinal cord transection. They used bilateral injection of glycine and then the did a spinal cord transection at the first cervical section. During the experiment they recorded renal, splenic splanchnic and T13 white ramus. They basically showed that renal and the T13 rami had greater response to blockade of RVLM compared to spinal transection; as for the other nerves (splenic and splanchnic)there was no difference.These data are suggesting that the majoirity os sympathoinbition is being driven at the level of the RVLM. -MD