[Alteration in bulbar conjunctiva microcirculation and interventional effect of Pentoxifylline after high-voltage electrical burn in rabbits].

OBJECTIVE: To study the changes in bulbar conjunctiva microcirculation (BCM) and the therapeutic effect of Pentoxifylline on BCM disturbance after high-voltage electrical burn (HEB) in rabbits. METHODS: Forty-five rabbits were divided into control group (C), electrical burn group (EB), and Pentoxifylline treatment group (PT) according to random number table, with 15 rabbits in each group. Model of HEB was reproduced in rabbits from EB and PT groups with voltage regulator and experimental transformer. Rabbits in C group were sham injured with the same devices without electrification. Changes in BCM were observed with microcirculation microscope at 15 minutes before HEB and 5 minutes, 1, 2, 4, 8 hour(s) post HEB (PHM or PHH), including: (1) morphology of microvessels, such as the discernible, diameters of arterioles, venules, and capillaries, the unevenness in caliber, and ischemic area; (2) dynamic changes in microvascular blood flow, such as blood flow speed in arterioles, venules, and capillaries, erythrocyte aggregation, and microthrombi formation; (3) condition of tissues surrounding microvessel, such as bleeding and exudation. Measurement data were processed with t test; enumeration data were processed with Fisher's exact test. RESULTS: (1) Morphology of microvessel: discernible of microvessels in EB and PT groups was decreased, but that of PT group was better than that of EB group. At PHM 5, diameter of arterioles, venules and capillaries was respectively (7.3+/-2.5), (12.3+/-2.4), (3.5+/-0.7) microm in EB group, all narrower than those of the control group [(14.6+/-3.1), (27.2+/-3.5), (9.0+/-1.4) microm, with t value respectively 5.23, 13.66, 14.04, P values all below 0.05]. Diameters of the microvessels in PT group [(10.2+/-3.8), (21.5+/-3.1), (7.1+/-1.2) microm] were larger than those in EB group (with t value respectively 2.21, 8.99, 10.18, P values all below 0.05). Diameters of arterioles, venules and capillaries in EB and PT groups recovered to the before HEB size at PHH 1. From PHH 2 to 8, arterioles and capillaries decreased gradually in caliber, venules dilated gradually in EB and PT groups, but the changes in PT group were not obvious. Thickness of microvessel was observed uneven in EB group at PHM 5, which lasted until PHH 8. Ischemia of the tissue was observed in EB group at PHM 5, which improved at PHH 2. Situation in PT group was better. (2) Dynamic changes in microvascular blood flow: at PHM 5, blood flow speed in arterioles, venules and capillaries was respectively (202+/-53), (198+/-44), (46+/-12) microm/s in EB group, all slower than those of the control group [(544+/-37), (359+/-32), (220+/-19) microm/s, with t value respectively 20.47, 11.51, 30.02, P values all below 0.05], and those of PT group [(335+/-42), (260+/-35), (119+/-23) microm/s] were faster than those of EB group (with t value respectively 7.55, 4.26, 14.85, P values all below 0.05). Blood flow speed in EB and PT groups recovered to the before HEB level at PHH 1. From PHH 2 to 8, blood flow speed decreased gradually in EB and PT groups, but that of PT group was faster than that of EB group. Erythrocyte aggregation in venules and capillaries was observed in EB group at PHM 5, which eased up at PHH 1, but aggregated at PHH 2, lasting until PHH 8. Obvious microthrombi were observed in EB group at PHH 2, which increased gradually. These changes were less obvious in PT group. (3) Condition of surrounding tissues of microvessel: in EB group, exudation was observed around microvessels at PHH 1, bleeding at PHH 2, with a worsening tendency. Changes in those in PT group were less obvious. CONCLUSIONS: HEB causes disturbance in BCM, but it can be ameliorated by Pentoxifylline.