STIMULATION OF DOG RVLM AND A5 AREA CHANGES SYMPATHETIC OUTFLOW TO VASCULAR BEDS WITHOUT EFFECT ON THE HEART

Citation
Lw. Dickerson et al., STIMULATION OF DOG RVLM AND A5 AREA CHANGES SYMPATHETIC OUTFLOW TO VASCULAR BEDS WITHOUT EFFECT ON THE HEART, American journal of physiology. Regulatory, integrative and comparative physiology, 41(3), 1997, pp. 821-839
Citations number
42
Categorie Soggetti
Physiology
ISSN journal
03636119
Volume
41
Issue
3
Year of publication
1997
Pages
821 - 839
Database
ISI
SICI code
0363-6119(1997)41:3<821:SODRAA>2.0.ZU;2-K
Abstract
Studies were conducted in anesthetized, vagotomized dogs while blood p ressure; blood flows in femoral, renal, mesenteric, and left circumfle x coronary arteries; electrocardiogram; and regional cardiac contracti le force were monitored. The ventral surface of the medulla was expose d, and presser sites in the rostral ventrolateral medulla (RVLM) were mapped by microinjections of L-glutamate. L-Glutamate activation of th e RVLM. evoked selective effects on different components of the cardio vascular system. Increases of 20-130 mmHg in blood pressure were accom panied by vascular conductance decreases in the femoral (-48 +/- 4%), renal (-30 +/- 4%), and mesenteric (-38 +/- 3%) arterial beds. These e ffects were without any obvious topography within the RVLM. There were only small or negligible changes in heart rate (HR), cardiac contract ile force, and coronary vascular conductance. Thus stimulation of the canine RVLM increased sympathetic tone selectively to structures other than the heart. Stimulation of the ventral medulla in a region that l ay rostral to the RVLM and ventromedial to the facial nucleus selectiv ely increased femoral vascular conductance by 103 +/- 33% and decrease d vascular conductance in the renal (-20 +/- 5%) and mesenteric (-15 /- 4%) arterial beds. There was no increase in HR, and the increases i n blood pressure were relatively small. Immunohistochemical data led u s, tentatively, to identify this rostral area as overlapping part of t he A5 area.