Lymph protein concentration in initial and collecting lymphatics of the rat

Lymph samples were obtained from villus initial and mesenteric prenodal collecting lymphatics of the anesthetized rat using standard micropuncture techniques. The protein concentrations of the lymph samples were determined using a fluorometric microassay. These procedures were performed on preparations either superfused with a modified Krebs solution or covered with paraffin oil. The protein-concentrating ability of the intestinal lymphatics was evaluated to test the osmotic theory of lymph formation. The mean initial lymph protein concentration in superfused preparations was 2.08 g/dl (SE = 0.20). The lymph protein concentration in collecting vessels in superfused preparations was 2.20 g/dl (SE = 0.19). The protein concentration from initial lymphatics in oil-covered preparation was 2.48 g/dl (SE = 0.17). The lymph protein concentration in collecting vessels in oil-covered preparations was 2.32 g/dl (SE = 0.15). The difference between initial and collecting lymph protein concentration found was an order of magnitude lower than that predicted by the osmotic theory. These results cast serious doubts on the effectiveness of the osmotic mechanism of lymph formation as it is presently defined.

EPR Study of Hydration of Portland Cement

The microscopic nature of the solidification of cement was studied via a measurement of the time dependence of the fraction of freely rotating spin probes by electron paramagnetic resonance with and without added retardants. The results seem to support the osmotic theory of cement hydration.

Solute—solvent coupling in epithelia: an electro-osmotic theory of fluid transfer

An epithelial model has been studied in which the volume flow is almost entirely due to electro-osmotic coupling in the boundary membranes. The system gives rise to secretions which are isotonic to the distal bathing solutions under a range of conditions, and predicts that intracellular and lateral spaces play an important role in the overall flow process. The behaviour of an extracellular shunt has also been studied, and it appears that both the water and salt flow rate are dependent upon its magnitude and ion specificity. The model is proposed as an alternative to theories of local osmotic equilibration whose applicability to most epithelial systems is doubtful.