What is the clinical evidence from this study?

Study design: Other. Population: Healthy (animal model) (n=11). Intervention: Supramaximal stimulation of sympathetic nerves vs. Baseline (no stimulation). Primary outcome: Change in hepatic volume (capacitance change) during constant flow perfusion (-2.40 ± 0.61 ml/kg (mean ± s.e.m.)).

What question did this study set out to answer?

To evaluate the contribution of the liver to total vascular capacitance and compliance under varying perfusion conditions and sympathetic nerve stimulation.

July 1, 1998Experimental PhysiologyOpen Access

Blood mobilization from the liver of the anaesthetized dog

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Key result

Supramaximal stimulation of sympathetic nerves at 16 Hz decreased hepatic volume by 2.40 ml/kg during constant flow perfusion, demonstrating the liver's major role in vascular capacitance.

Why the study?

Does sympathetic nerve stimulation reduce hepatic blood volume in anaesthetized dogs?

Population

11 Beagle dogs weighing 14-20 kg, anaesthetized with chloralose.

Comparison

Supramaximal stimulation of splanchnic… vs Baseline (absence of sympathetic stimulation).

Design

Preclinical

Authors

BNBJ NobleUniversity of Leeds MDMJ DrinkhillUniversity of Leeds DMD. S. MyersUniversity of Leeds

Discussion

Member takes

Implication

Confirms hepatic capacitance during sympathetic activation in dogs; leaves open translation to human cardiovascular regulation.

Key Points

To evaluate the contribution of the liver to total vascular capacitance and compliance under varying perfusion conditions and sympathetic nerve stimulation.
Vascularly isolated livers of chloralose-anaesthetized dogs were perfused through the portal vein and hepatic artery at either constant pressures or constant flows, with hepatic venous drainage at constant pressure.
Hepatic blood volume shifts and vascular resistance changes were evaluated from net inflow-outflow differences and perfusion pressure changes during 16 Hz sympathetic nerve stimulation.
Sympathetic nerve stimulation at 16 Hz under constant flow reduced hepatic volume by -2.40 ± 0.61 ml (kg body weight)⁻¹, an active capacitance response that did not differ significantly under constant pressure perfusion.
Stimulation during constant flow increased portal venous and hepatic arterial pressures by +0.67 ± 0.13 kPa and +4.92 ± 0.67 kPa, respectively.
Liver compliance in response to changes in hepatic venous pressure was +5.44 ± 0.18 ml kg⁻¹ kPa⁻¹, with no evidence of an outflow sphincter mechanism.

Structured PICO

Does sympathetic nerve stimulation reduce hepatic blood volume in anaesthetized dogs?

Population

11 chloralose-anaesthetized Beagle dogs weighing 14-20 kg were studied to evaluate the liver's contribution to vascular capacitance and compliance.

Intervention

Supramaximal stimulation of splanchnic sympathetic nerves at 4 Hz and 16 Hz during constant flow or constant pressure perfusion of the vascularly isolated liver.

Comparator

Baseline (absence of sympathetic stimulation).

Outcome

Change in hepatic blood volume (capacitance change) and vascular resistance (assessed from changes in inflow pressures or flows).surrogate

Main Result

Mean Difference: -2.4

The liver acts as a major capacitance organ and is highly compliant, mobilizing significant blood volume during sympathetic stimulation without evidence of a hepatic outflow sphincter.

Limitations

Animal model (dogs) which may not perfectly extrapolate to humans due to species differences in splenic function
Use of anaesthesia (chloralose) which might affect autonomic reflexes
Extensive surgical preparation including open chest and abdomen
Extrapolation to humans assumes similar responses despite humans lacking a large contractile spleen

Cite This Study

Noble et al. (1998) studied Healthy (animal model) (n=11). Supramaximal stimulation of sympathetic nerves vs. Baseline (no stimulation) was evaluated on Change in hepatic volume (capacitance change) during constant flow perfusion (-2.40 ± 0.61 ml/kg (mean ± s.e.m.)). Supramaximal stimulation of sympathetic nerves at 16 Hz decreased hepatic volume by 2.40 ml/kg during constant flow perfusion, demonstrating the liver's major role in vascular capacitance.

synapsesocial.com/papers/6a993e83dea2d226f518fb73 https://doi.org/10.1113/expphysiol.1998.sp004134

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Blood mobilization from the liver of the anaesthetized dog

Discussion

Member takes

Implication

Key Points

Structured PICO

Main Result

Limitations

Cite This Study

Blood mobilization from the liver of the anaesthetized dog

Discussion

Member takes

Implication

Key Points

Structured PICO

Main Result

Limitations

Cite This Study

Also Consider

Also Consider