A protease inhibitor attenuates gastric erosions and microcirculatory disturbance in the early period after thermal injury in rats

Effects of cimetidine, a histamine type 2 receptor antagonist, on microcirculatory disturbance of the stomach induced by full-thickness burn injuries as a model for surgical stress in rats

BACKGROUND

We have reported the preventive effect of cimetidine, a histamine type 2 receptor antagonist, on decreased gastric mucosal blood flow induced by burn injury, a model of surgical stress.

OBJECTIVE

The present study was performed to assess the effects of cimetidine on gastric microcirculatory disturbance induced by surgical stress.

METHODS

Twelve male Wistar rats were anesthetized and a 30% full-thickness dorsal scald burn was inflicted. The total lengths of gastric erosions were measured using stereoscopic microscopy. Microvascular images in the basal region of the gastric mucosa were observed using an intravital microscope, and the diameters of venules and collecting venules were measured. Rolling leukocytes inside and along the venules, an indication of endothelial damage to the microcirculation, were observed. The rats were assigned to the cimetidine group or the control group (both, n = 6). Cimetidine 100 mg/kg was administered 30 minutes before and 2.5 hours after infliction of the burn injury. Animals in the control group were given only isotonic saline. Values are expressed as mean (SD).

RESULTS

Contraction of venules was easily observed in all rats in the control group. However, venular contraction was rarely observed in the cimetidine group. The total length of gastric erosions was significantly decreased in the cimetidine group compared with the control group (0.93 [0.58] μm vs 5.98 [5.18] μm, respectively; P < 0.05). The percentages of rolling leukocytes that passed the confluence of a prevenule and a venule were also significantly decreased in the cimetidine group compared with the control group (4.7% [7.3%] vs 22.6% [5.7%]; P < 0.01). The diameters of the venules and collecting venules were significantly larger in the cimetidine group (57.3 [6.8] μm and 75.9 [3.6] μm, respectively) than in the control group (30.9 [9.2] μm and 46.8 [8.0] μm, respectively) (both, P < 0.01).

CONCLUSIONS

The present study suggests that cimetidine may have a protective effect against gastric microcirculatory disturbances induced by burn injury, a model of surgical stress.

Sialyl Lewis X analog attenuates gastric microcirculatory disturbance and gastric mucosal erosion induced by thermal injury in rats

BACKGROUND AND AIM

We hypothesize that selectins, which are adhesion molecules, are involved in the pathogenesis of stress-induced gastropathy. We therefore investigated whether the novel Sialyl Lewis X (SLex) analog, which is a clinically available antagonist of selectins, attenuate gastric mucosal lesions induced by thermal injury.

METHODS

Male Wistar rats were anesthetized and a 30% full-skin thickness dorsal burn was inflicted on each rat. The SLex analog was administrated into the jugular vein 30 min before and 2.5 h after the thermal injury. Saline was administered to the vehicle group. The distribution of E-selectin immunoreactivity on the luminal side of the gastric mucosal microvascular network was observed by immunohistochemical methods. Active oxygen species were measured by the chemiluminescence method. Rolling leukocytes and endothelial damage, investigated by using Monastral Blue B (MBB), of the gastric mucosal microvascular network were observed through an intravital microscope.

RESULTS

A high intensity of E-selectin fluorescence was observed on the luminal surface of the venular endothelial cells 5 h after thermal injury in the vehicle group. However, E-selectin-associated fluorescence was almost negligible in the non-injury group and in the SLex analog group. The SLex analog also attenuated the rolling of leukocytes in the venules, venular deposits of MBB, luminol-dependent chemiluminescence activities, and gastric mucosal lesion formation.

CONCLUSION

It is suggested that the selectin family is involved in gastric microcirculatory disturbance and the pathogenesis of gastric mucosal lesions after thermal injury. A novel preventive therapy using the SLex analog is considered to effectively protect both gastric microcirculation and the gastric mucosa in rats with thermal injury.

A new technique for the analysis of endogenous mediators released following thermal injury

Few techniques today enable us to measure the complex processes taking place inside a burn wound in vivo. The present in vivo technique was based on a standardised burn model in rat skin. A partial- or full-thickness burn was induced and resulted in a gelatinous oedema located between the skin and the underlying rectus muscle. The oedema has distinct borders to the surrounding connective tissue and is separated and removed easily for further analysis. Myeloperoxidase (MPO) activity used as indicator of neutrofil infiltration was increased significantly in the burn oedema versus non-burned skin. Leukocyte metabolic activity was high as shown by significantly higher free radical formation (ESR) in the oedema than in surrounding burned and non-burned tissue. Leukocyte viability measured by Trypan blue stain was 70% in the oedema of full-thickness burns. In order to decide whether processes taking place in the oedema communicate freely with systemic circulation, we conducted a number of experiments. Results show in burned animals in vivo that intravenous administration of indomethacin induced a strong inhibition of PGE(2) in the burn oedema as compared with saline but, as expected, had no significant effect on LTB(4) synthesis. In conclusion, the present technique allows us to analyse the processes taking place inside the burn wound in vivo and to evaluate the effects of various agents on these processes.