Differential regulation of sympathetic nerve activity by lateral and medial subregions of the rostral ventral medulla.
Microinjections of lidocaine were used to examine the contributions of two subregions of the RVM, RVLM (2 mm lateral to midline) and RVMM (1 mm lateral to midline) to the maintenance of AP and SNA in urethane-anesthetized rats. Lidocaine microinjected into either site reduced AP to similar levels. Blockade of RVLM and RVMM produced a small further reduction in AP and essentially abolished neurogenic maintenance of AP. Blockade of either RVLM or RVMM elicited similar falls in RSNA. In contrast, inactivation of RVLM elicited larger falls in lumbar chain (LSNA) and splanchnic (SSNA) SNA than did inactivation of the RVMM. Combined blockade of RVLM and RVMM essentially eliminated LSNA, while RSNA and SSNA were reduced only 60%. From these data we conclude that (1) RVLM and RVMM contribute equally to the neurogenic maintenance of AP; (2) RVLM and RVMM differentially control the activity of individual sympathetic nerves; and (3) a substantial portion of RSNA and SSNA originates outside the RVM and may not be involved in vasomotor control.
Varner
K J
KJ
Grosskreutz
C L
CL
Cox
B F
BF
Brody
M J
MJ
D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D008297:Male; D008526:Medulla Oblongata / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013564:Sympathetic Nervous System / Q000502:physiology*