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Pilot investigation of the cardiopulmonary baroreflex control of ventricular contractility
Author(s) -
Mukkamala Ramakrishna,
SalaMercado Javier A,
Chen Xiaoxiao,
Hammond Robert L,
Ichinose Masashi,
O'Leary Donal S
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.645.10
Subject(s) - baroreflex , propranolol , medicine , hemodynamics , heart rate , anesthesia , cardiology , central venous pressure , blood pressure , contractility , vascular resistance
The cardiopulmonary (CP) baroreflex responds to an increase in central venous pressure (CVP) by increasing heart rate (HR) and decreasing vascular resistance in dogs. However, the CP baroreflex control of ventricular contractility (VC) is less understood. A CVP increase could cause either an increase in VC to maintain CVP, much like the Bainbridge effect, or a decrease in VC to blunt the ensuing increase in arterial blood pressure (ABP), much like the control of the vasculature. Our aim is to explain the CP baroreflex control of maximal ventricular elastance (E max ), which is the best available index of VC. We measured spontaneous beat‐to‐beat hemodynamic variability from two conscious dogs before and after propranolol administration. We then identified the transfer function relating beat‐to‐beat fluctuations in CVP to E max (CVP→E max ) while mathematically eliminating the influences of ABP fluctuations on E max via the arterial baroreflex and HR fluctuations on E max via the force‐frequency relation. The CVP→E max transfer function revealed that an increase in CVP caused an increase in E max (0.17 ml −1 gain value) during the control condition and no change in E max during the propranolol condition. Based on these pilot findings, the CP baroreflex appears to respond to an increase in CVP by increasing VC via the β‐sympathetic nervous system. This work was supported by the NIH (HL‐55473, HL‐080568) and NSF (CAREER 0643477).