Background and purpose: The mechanism by which electrical stimulation affects edema has not been elucidated. The purpose of this study was to determine whether subcontraction high-voltage stimulation (SC-HVS) (ie, electrical stimulation that did not elicit a visible contraction) applied to the right hind limbs of rats would (1) alter the rate of lymphatic uptake of injected albumin labeled with Evans blue dye (AL-EBD) and (2) affect experimentally induced edema.
Subjects and methods: The paws of 28 anesthetized Sprague-Dawley rats (mean weight = 263 g, SD = 48 g) were injected with AL-EBD. The experimental group (n = 13) received 1 hour of SC-HVS, and the control group (n = 15) received sham treatment consisting of the same treatment administered to the experimental group but without the SC-HVS. Blood samples and volume measurements were obtained at intervals over a 7-hour period.
Results: Analysis of variance and post hoc testing indicated that higher amounts of AL-EBD were taken up by the lymph of the experimental group animals as compared with the control group animals at each time period following the treatment. The experimental group's AL-EBD reached significance immediately after treatment, whereas the control group required an additional 4 hours. There was no significant reduction in limb volume in either group.
Conclusion and discussion: The SC-HVS significantly increased the uptake of AL-EBD by lymphatic vessels, but it did not cause a significant decrease in the induced edema. The results of this study indicate that SC-HVS has the potential to reduce edema by increasing lymphatic uptake of proteins.