Medical/biological study (experimental study, observational study)

Influence of low frequency electric fields on anti- and pro-coagulability of the vascular endothelium: new insights into high-voltage electrical injury med./bio.

By: Ulrich D, Pallua N, Lichtenegger F, Hafemann B, Silny J

Published in: Thromb Haemost 2004; 91 (5): 1000-1008

After high-voltage electric injury, patients often show tissue necrosis and thrombosis of blood vessels even remote from entry and exit site of electrical current.
In this study, blood coagulation markers and fibrinolytic avtivity (plasma levels of thrombin-antithrombin (TAT), prothrombin fragment 1+2 (F₁₊₂), tissue-type plasminogen activator (t-PA) and its inhibitor PAI-1 (type-1 plasminogen activator inhibitor)) were determined in vivo in three patients with high-voltage injury for 96 hours after trauma.
In order to examine a possible effect on haemostasis related to endothelial cell damage, protein S, tissue factor (TF), endothelin-1 (ET-1), prostacyclin (PGI₂), nitric oxide (NO), t-PA, and PAI-1 were determined for 72 hours in vitro in cell culture supernatant of human umbilical vein endothelium cells (HUVECs) that had been exposed to 1, 10, 30, and 50 electric field periods of 50 Hz with field strength of 60 V/cm and duration of 20 ms. Furthermore, expression of thrombomodulin was determined.

Exposure	Parameters
Exposure 1: 50 Hz Exposure duration: 20 ms periods interupted by 10 s intervals, 1, 10, 30 and 50 periods	electric field strength: 60 V/cm unspecified

Frequency	50 Hz
Type	electric current
Waveform	sinusoidal
Exposure duration	20 ms periods interupted by 10 s intervals, 1, 10, 30 and 50 periods

Exposure source	electrode
Chamber	culture chamber (9 x 9 x 2 cm lxwxh) with 4 mm of culture medium maintained at 37°C
Setup	Electrodes were placed on the inside of the cover of the culture plate at two opposite sides
Sham exposure	A sham exposure was conducted.

Measurand	Value	Type	Method	Mass	Remarks
electric field strength	60 V/cm	unspecified	unspecified	-	-

Exposed system:

intact cell/cell culture
human umbilical vein endothelium cells (HUVECs)
human
partial body: patient 1: hands; patient 2: left hand, right foot, right arm, and upper part of body; patient 3: hand, feet, legs

cell function: coagulation markers (plasma levels of TAT, F₁₊₂); fibrinolytic avtivity (t-PA, PAI-1); haemostasis (protein S, TF, ET-1, PGI₂, NO, t-PA, and PAI-1) (ELISA); expression of thrombomodulin (immunohistochemistry)

Investigated system:

Investigated organ system:

Time of investigation:

Blood clotting activation could be found in the patients by increased levels of F₁₊₂ and TAT between 12 and 72 hours after injury, whereas fibrinolysis was disturbed due to high PAI-1. One patient presented thrombosis of vessels by day 3.
In vitro, PAI-1 increased significantly in medium of endothelium cells with an application of 30 and 50 periods between 2 and 48 hours after exposure. Between 4 and 72 hours, the concentration of t-PA was significantly lower in the medium of endothelium cells exposed to 10, 30, and 50 periods, whereas there was a significant increase in the concentration of TF in the cell groups with an application of 30 and 50 periods. 24, 48, and 72 hours after injury (exposure), there was just weak or no staining for thrombomodulin in the cells with an application of 30 and 50 periods.
The disturbed balance between blood clotting system and fibrinolysis observed in vitro after electric injury might explain the clinical observation of a progressive thrombosis of blood vessels after electric injury leading to tissue loss.

Study character: