Noble, B.J., Drinkhill, M.J., Myers, D.S. and Hainsworth, R. (1998) Blood mobilization from the liver of the anaesthetized dog. Experimental Physiology, 83 (4). pp. 513-522. ISSN 0958-0670Full text available as:
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The abdominal circulation contains a high proportion of the total blood volume and this can change either passively in response to changes in vascular distending pressure or actively (termed a capacitance response) to changes in sympathetic nervous activity. The liver is the largest abdominal organ and this study was designed to evaluate its potential contribution to overall vascular capacitance and compliance. In chloralose anaesthetized dogs, the liver was vascularly isolated, perfused through the portal vein and hepatic artery at either constant pressures or constant flows and drained from the hepatic veins at constant pressure. Changes in vascular resistance were assessed from changes in inflow pressures or flows and hepatic blood volume was determined by differences between net inflow and outflow. During constant flow perfusion the change in hepatic volume (capacitance change) in response to supramaximal stimulation of sympathetic nerves at 16 Hz was (mean ± S.E.M.) -2·40 ± 0·61 ml (kg body weight)-1. This response was not significantly different during constant pressure perfusion. The changes in portal venous and hepatic arterial pressures during stimulation at constant flow perfusion were +0·67 ± 0·13 and +4·92 ± 0·67 kPa, respectively. The compliance of the liver, assessed as the change in volume to a change in hepatic venous pressure, was +5·44 ± 0·18 ml kg-1 kPa-1.
These results indicate that the liver has a major capacitance role, comparable to that of the canine spleen and, in addition, is highly compliant. No evidence was found to suggest that a sphincter on the hepatic outflow exists. Assuming similar responses occur in humans, who do not possess a large contractile spleen, the liver would be the most important controllable blood reservoir in the body.
|Copyright, Publisher and Additional Information:||© Cambridge University Press|
|Institution:||The University of Leeds|
|Academic Units:||The University of Leeds > Faculty of Medicine and Health (Leeds) > School of Medicine (Leeds) > Leeds Institute of Genetics, Health and Therapeutics (LIGHT) > Academic Unit of Cardiovascular Medicine (Leeds)|
|Depositing User:||Repository Assistant|
|Date Deposited:||26 May 2006|
|Last Modified:||05 Jun 2014 19:31|
|Publisher:||Cambridge University Press|