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Baroreflex changes only stressed volume not the slope of the venous return surface
Author(s) -
SAKAMOTO TAKAFUMI,
MURAYAMA YOSHINORI,
SAKAMOTO KAZUO,
TOBUSHI TOMOYUKI,
TANAKA ATSUSHI,
SAKU KEITA,
HOSOKAWA KAZUYA,
ONIZUKA KEN,
FUJINO TAKEO,
SUNAGAWA KENJI
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.1027.13
Subject(s) - venous return curve , baroreflex , mean circulatory filling pressure , ventricle , anesthesia , cardiac output , medicine , central venous pressure , cardiology , circulatory system , blood volume , blood pressure , heart rate , hemodynamics
Background Although Guyton established the framework of circulatory equilibrium by cardiac output (CO) and venous return (VR), the contribution of the left ventricle (LV) was obscured. To clarify this, we defined the VR as a function of both right (P RA ) and left (P LA ) atrial pressures, formulated as VRS=V/W–(G S P RA +G P P LA ) (VRS: VR surface, V/W: maximum VR, G S : systemic and G P : pulmonary venous conductance) and demonstrated the uniformity of those parameters across animals (AJP 2004, 2005). However how baroreflex impacts the VR remains unknown. Methods/Results In 6 anesthetized, vagotomized dogs, we isolated carotid sinuses and controlled carotid sinus pressure. We replaced both ventricles by roller pumps. We first matched CO of two pumps. We then momentarily changed CO of either one of them to shift blood between the pulmonary and systemic circulations. We shifted the volume at least 6 times. We ran the same protocol at CSP of 100 or 120 mmHg. We applied multivariate regression and determined V/W, G P , and G S . The coefficient of determination ranged 0.89–0.99 indicating the flatness of the VRS. Decreasing CSP increased V/W (246±149 vs. 291±130 ml/kg/min, p<0.01), whereas did not change G S (22±9 vs. 25±9 ml/kg/min/mmHg, ns) or G P (3.5±2 vs. 3.9±1.8 ml/kg/min/mmHg, ns). Conclusions Baroreflex changed the maximum VR, thereby stressed volume significantly, but did not change the slope of the VRS.