There a lot of disputes about the concentration of potassium in the plasma of animals which are in hemorrhagic states. Only little change, if any, of the concentration was revealed in spite of remarkable deteriorations in the funtion of the skeletal muscle of the hypotensive animal.
There are also some evidences of potassium loss in the muscle fiber and considerable accumulation of that ion in the extracellular fluid which bathes the muscle fibers.
However, because of lack of equilibration in the ionic distirbution between the local extracellular fluid and circulating plasma, no indication of rise in the plasma potassium concentration has been noticed as mentioned above. The discrepancies could be attributable to the drop of perfusion pressure as well as the diminished blood flow in the muscular tissue. Morever, some diffusional restriction was also regarded to play a role to boost the discrepancies.
In the present experiment, fourteen adult anesthetized rabbits were shed through the polyethylene tube inserted into the right carotid artery and maintained blood pressure as low as 52 mmHg for 3 hours. After then, one of the lower extremities of each animal was isolated from its general circulation and was perfused with its own blood withdrawn previously. The perfusion pressure ranged 90-110 mmHg and the flow rate was 1.5m1/ min.
Blood samples from the outlet vein were collected successively and the concentrations of sodium, potassium and T1824 which was mixed in the blood reservoir were measured.
The purpose of the research were two folds. The first one was to prove the accumulation of the potassium ion in the extracellular fluid of the lower extremity by analyzing the perfusate which came from the tissue, and secondly was to estimate the volume of distribution of T1824 which does not necessarily represent the intravascular volume.
The results obtained are as follows:1. Blood samples withdrawn before the hemorrhage(Bo), those kept in the reservoir for 3 hours(Bh), and those taken from the animals after 3 hours period of the hypotensive state (Bf) revealed essentially the same figures in the concentration of potassium ion of the plasma, showing that plasma value did not reflect the deleterious transmembrane distribution of potassium.
2. The blood was perfused to the lower extremity after hypotensive state with constant flow rate and considerably high blood pressure. The perfusate showed no significant changes in the concentration of sodium ion.
On the other hand, the perfusate showed 32% increase in the concentration of potassium ion, suggesting a persistent local extracellular accumulation of potassium ion during the shock period.
3. The accumulation of potassium ion did not disappear promptly, suggesting a large scale of potassium pool or continued outward release of that ion.
4. The volume of distribution of T1824 was estimated as 4.5+1. 1m1. The significance of this figure was speculated and further studies were anticipated.
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