|
|
||||||||
Department of Anatomy and Neurobiology, St. Louis University School of Medicine, St. Louis, Missouri 63104-1028
Investigators have demonstrated pressor areas in the medullas of various species. The present study precisely localized the pressor area in the caudal medulla of the rat and determined its projections to the caudal and rostral ventrolateral medulla. The caudal medulla first was mapped grossly in rats with injections (30 nl) of glutamate (30-, 15-, and 7.5-nmol doses) placed 0.5, 1.0, and 1.5 mm caudal to the calamus scriptorius, 1.0, 1.5, and 2.0 mm lateral to the midline, and 1.8, 1.7, and 1.6 mm ventral to the dorsal medullary surface, respectively, and their arterial pressures were recorded. One of these nine injections showed significant increases in arterial pressure. We micromapped this area with a total of 27 injections of glutamate (10 nl; 5 nmol) placed 300 µm apart at 3 different dorsoventral levels. This micromapping study pinpointed the precise location of caudal pressor area (CPA) neurons in a restricted region lateral to the caudal end of the lateral reticular nucleus and ventromedial to the medullary dorsal horn near the level of the pyramidal decussation. Injections of glutamate into this spot, 1.0 mm caudal to the calamus scriptorius, 2.0 mm lateral to the midline, and 1.7 mm ventral from the dorsal surface of the medulla, induced significant increases in arterial pressure. The neuroanatomic connections of neurons in the CPA to the ventrolateral medulla were then investigated with iontophoretic injections of either the anterograde tracer biotinylated dextran amine (BDA) made into the CPA or the retrograde tracer FluoroGold (FG) injected into either the caudal or rostral ventrolateral medulla. BDA injections resulted in bouton-laden fibers throughout both caudal and rostral portions of the ventrolateral medulla. Either of the FG injections resulted in numerous spindle-shaped neurons interspersed between the longitudinal fiber bundles running through the CPA area. The proximity of the CPA neurons to the A1 catecholaminergic cell group is discussed.
cardiovascular; glutamate; micromapping; blood pressure; caudal medulla
This article has been cited by other articles:
![]() |
K. Iigaya, H. Kumagai, H. Onimaru, A. Kawai, N. Oshima, T. Onami, C. Takimoto, T. Kamayachi, K. Hayashi, T. Saruta, et al. Novel axonal projection from the caudal end of the ventrolateral medulla to the intermediolateral cell column Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2007; 292(2): R927 - R936. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Seyedabadi, Q. Li, J. R. Padley, P. M. Pilowsky, and A. K. Goodchild A novel pressor area at the medullo-cervical junction that is not dependent on the RVLM: efferent pathways and chemical mediators. J. Neurosci., May 17, 2006; 26(20): 5420 - 5427. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |