OBJECTIVE: To observe the dynamic alteration in Gq/11 protein expression in the lung, brain, heart, kidney, liver and small intestine of rats suffering from acute respiratory distress syndrome (ARDS), and to explore the pathophysiological mechanism of ARDS in terms of signal transduction.
METHODS: Forty male Wistar rats were randomly divided into oleic acid (OA) groups (n=32) and control group (n=8). OA groups included four subgroups: 30, 60, 90, 120 minutes (each n=8). An ARDS model in rats was reproduced by intravenous injection of OA 0.2 ml/kg in 2 minutes, and control group was given normal saline by the same way. Lactate dehydrogenase (LDH), malondialdehyde (MDA) and angiotensin converting enzyme (ACE) in the plasma and the above-mentioned organs were measured. G alpha q/11 protein expression in these organs was examined by Western blotting.
RESULTS: Compared with control group, LDH activity in the plasma and the heart 30 minutes after injection of OA gradually increased [plasma (kU/L): 9.69+/-1.66 vs. 6.27+/-1.70, heart (kU/g): 0.81+/-0.12 vs. 0.59+/-0.09], and in the lung, brain, kidney, and small intestine 60 minutes after injection of OA also gradually increased [lung (kU/g): 1.15+/-0.19 vs. 0.87+/-0.11, brain (kU/g): 2.27+/-0.37 vs. 1.53+/-0.61, kidney (kU/g): 1.13+/-0.26 vs. 0.64+/-0.09, small intestine (kU/g): 0.72+/-0.10 vs. 0.60+/-0.13], and in the liver (kU/g) 90 minutes after injection of OA gradually increased (0.50+/-0.14 vs. 0.39+/-0.05, P<0.05 or P<0.01). MDA concentration in the heart (micromol/g) 30 minutes after injection of OA gradually increased (2.20+/-0.47 vs. 1.45+/-0.27), and in the plasma, lung and kidney 60 minutes after injection of OA gradually increased [ plasma (micromol/L): 3.10+/-0.58 vs. 2.33+/-0.35, lung (micromol/g): 5.56+/-1.30 vs. 2.05+/-0.52, kidney (micromol/g): 1.61+/-0.27 vs. 0.98+/-0.42], and in the brain, liver and small intestine 90 minutes after injection of OA gradually increased [brain (micromol/g): 6.78+/-1.38 vs. 5.83+/-1.58, liver (micromol/g): 2.58+/-0.68 vs. 2.11+/-0.42, small intestine (micromol/g): 2.14+/-0.51 vs. 0.81+/- 0.26, P<0.05 or P<0.01]. ACE activity was reduced in the plasma and lung 60 minutes after injection of OA [ plasma (micromolxmin(-1)xL(-1)): 15.47+/-1.68 vs. 19.87+/- 3.11, lung(micromolxmin(-1)xg(-1)): 20.61+/-1.81 vs. 26.26+/-1.93], but in the kidney (micromolxmin(-1)xg(-1)) it was gradually increased (15.92+/-1.20 vs. 13.67+/-2.26), and in the small intestine (micromolxmin(-1)xg(-1)) 90 minutes after injection of OA it gradually increased (4.42+/-0.34 vs. 3.29+/-0.24, all P<0.01). G alpha q/11 protein expression in the lung and small intestine obviously increased 30 minutes after injection of OA [lung: (119.24+/-2.38)% vs. (100.00+/-18.74)%, small intestine: (138.91+/-23.03)% vs. (100.00+/-19.43)%], and in the brain, heart and kidney increased 60 minutes after injection of OA [brain: (141.85+/-33.82)% vs. (100.00+/-16.81)%, heart: (124.72+/-24.05)% vs. (100.00+/-16.04)%, kidney: (123.98+/-25.74)% vs. (100.00+/-8.50)%], and in the liver increased 90 minutes after injection of OA [(134.34+/-19.14)% vs. (100.00+/-13.04)%, P<0.05 or P<0.01]. A positive correlation between the change in G alpha q/11 protein expression and LDH in these organs (r=0.584, P<0.05) was found.
CONCLUSION: Up-regulation of Gq/11 protein expression in the lung, brain, heart, kidney, liver and small intestine may induce abnormal activity of phosphatidyl inositol signal transduction and thus plays a role in the production of multiple organ injury during ARDS.