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Biomedical subjects

K Thornbury

Publications and source records attributed to K Thornbury.

3 recordsLinked to original sources
PubMed1987

Peripheral lymphatic responses to outflow pressure in anaesthetized sheep.

1. Lymph flow and pressure fluctuations were measured by cannulating popliteal efferent and distal hind-limb afferent lymphatic vessels in anaesthetized sheep. The cannula outflow height was raised above the vessels to increase lymphatic outflow pressure. 2. Lymph flow decreased non-linearly as the outflow was raised. The rate of decrease increased with increasing outflow height. 3. Lymphatic contraction frequency rose and stroke volume fell with increasing outflow height. 4. The calculated power necessary to move lymph along the cannula initially increased with outflow height but it reached a peak and was reduced again by raising the outflow further. Calculated lymphatic stroke work followed a very similar pattern. 5. Lymph flow was maintained up to a greater outflow height in afferent than in efferent vessels. Curves relating frequency, power and stroke work to outflow height were shifted to the right in the afferent lymphatics. 6. These results are consistent with an intrinsic lymphatic pump which can be stimulated by increasing pressure. At high pressures, however, the pump fails.

Animals↗
PubMed1986

A method for studying lymphatic pumping activity in conscious and anaesthetized sheep.

A 20 cm length of the main mesenteric lymph duct in the sheep was cannulated at both ends and measurements were made in both conscious and anaesthetized animals of the ability of the duct to pump saline from an inflow reservoir to an outflow at the same height. Fluid was propelled only when the lymphatic contracted and this was unaffected by movements of the animal round the cage or by fluctuations in abdominal pressure or by respiratory movements. It was confirmed that the mesenteric duct was 'isolated' from the rest of the lymphatic system by closing the inflow tap whereupon fluid propulsion ceased. Raising transmural pressure by varying inflow and outflow by the same amount had the effect of increasing fluid output; this was achieved by an increase in both the frequency and force of lymphatic contractions. Lymphatic frequency of contraction and fluid output increased when the animals were frightened. Intravenous infusions of noradrenaline increased the frequency of lymphatic contraction and increased fluid propulsion, while isoprenaline infusions depressed flow. This preparation demonstrates that it is possible to study the control of lymphatic pumping in conscious sheep without the complication of changing rates of lymph formation.

Anesthesia, General↗