LUDWIG,CARL AND THE LOCALIZATION OF THE MEDULLARY VASOMOTOR CENTER - OLD AND NEW CONCEPTS OF THE GENERATION OF SYMPATHETIC TONE

In Carl Ludwig's laboratories in Leipzig, P. Owsjannikow (1871) and C. Dittmar (1873) performed precise, histologically controlled lesioning experiments into the question of the location of the vasomotor center in the medulla oblongata. A small area in the ventrolateral parts of the medulla with its caudal border 3 mm cranial to the obex and an ext ension of 3-4 mm in cranial direction was described as the vasomotor a rea which has to be left intact for normal vasomotor tone and reflexes . This finding, ignored for more than 100 years, is the most precise d escription of what is known today as the location of spinally projecti ng sympatho-excitatory neurones, named the RVML region. Already in the se early publications the question of the origin of basic vasomotor to ne within these areas was raised and the possibilities of automaticity and reflexogenic input were discussed. Both possibilities are still v alid today and under current investigation. A specific chemosensitivit y of the RVLM neurones has been demonstrated during the recent decade and its role with regard to the generation of the sympathetic tone and the nervous control of the entire cardiovascular system is being disc ussed.