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Biomedical subjects

I C Roddie

Publications and source records attributed to I C Roddie.

13 recordsLinked to original sources
PubMed1990

The effect of acute changes in blood flow on local lymph flow in the limbs of anesthetized sheep.

A study was made of the effects of acute changes in local blood flow on lymph flow in the feet of anesthetized sheep. Lymph outflow pressure and flow and venous pressure were measured in cannulated vessels draining the foot region. Local volume changes were also measured. Acute reductions in blood flow were produced by sudden occlusion of the circulation to the limbs with a pneumatic cuff for periods of up to 1.5 hours. During the first 10 min of occlusion, there was little change reaching about 25% of its control value after 40 min of arrest. On release of the circulation, lymph flow rose almost immediately to levels above the control value, resulting in a hyperlymphia whose size and duration was related to the duration of the circulatory arrest and the limb volume changes that followed. The results indicated that lymph flow can continue, albeit at reduced rates for long periods after circulatory arrest and that during reactive hyperaemia, there is a brisk hyperlymphia whose size and time course is similar to that of the limb volume changes.

Anesthesia, General↗
PubMed1989

Lymph flow in sheep limbs during local exposure to subatmospheric pressure.

1. Lymph flow and pressure were measured via cannulae inserted into afferent lymphatics draining the feet of anaesthetized sheep. 2. When the cannula outlet was at limb level, local exposure of the limb to graded decreases in ambient pressure caused graded increases in lymph flow with pressure values down to -50 mmHg. 3. When the cannula outlet was lowered below limb level to offset the negative pressure gradient imposed on the lymphatic vessels by suction, lymph flow rose progressively with decreasing ambient pressure values down to -70 mmHg. 4. When negative pressure gradients were imposed on the lymphatic vessels by raising the lymphatic cannula outlet in progressive steps above limb level, the vessels were able to expel lymph against gradients of up to 50 mmHg but lymph flow was greatly reduced against a gradient of 70 mmHg. 5. The results suggest that subatmospheric pressure may affect local lymph flow in two ways. By increasing blood capillary transmural pressure it may increase lymph flow by increasing tissue fluid formation. By imposing a negative pressure gradient along the lymphatics it may decrease lymph flow, especially at the most negative pressures, and the lymph flow response to subatmospheric pressure may be the algebraic sum of both effects.

Animals↗
PubMed1976

Venous distensibility during pregnancy determined by graded venous congestion.

The increase in volume of the human calf and forearm during pregnancy resulting from graded venous congestion has been measured plethysmographically in the raised leg and forearm of 10 recumbent subjects during and after pregnancy. Normal pressure volume curves were determined and the alterations in this curve over the various stages of gestation were presumed to indicate an alteration in the distensibility of the capacity blood vessels. This distensibility was found to increase with the progression of pregnancy in both the forearm and the calf particularly after the thirtieth week of pregnancy. The distensibility, however, appeared to return to below the 10 week gestation level at the eighth postpartum week. The increase in distensibility was greater in the calf than in the forearm although both were significantly increased.

Adult↗
PubMed1976

The effect of transmural pressure on pumping activity in isolated bovine lymphatic vessels.

1. Isolated preparations of bovine mesenteric lymphatics containing about seven valved segments were cannulated and set up in a perfusion system so that, when the preparation was not contracting, the inflow and outflow pressures were exactly equal and there was no flow through the preparation. 2. Transmural pressure was varied by raising or lowering the inflow and outflow pressures simultaneously by the same amount. 3. The isolated vessels showed rhythmic spontaneous activity; it consisted of quick contractions which spread rapidly over the entire preparation, each followed by a rapid relaxation and a diastolic pause. 4. With each contraction, the preparation decreased in both length and diameter and generated an outflow pressure which pumped fluid in the direction determined by the orientation of the values. 5. Raising the transmural pressure in the preparation increased the output of the preparation; this was achieved by an increase in both the frequency and force of the individual contractions. 6. It was concluded that bovine lymphatics could propel fluid by their intrinsic activity at a rate which was related to the degree of distension of their walls.

Animals↗