[Effect of calcium-sensitive receptors on endothelial nitric oxide synthase and nitric oxide in neonatal mice with persistent pulmonary hypertension].

OBJECTIVE: To study the effect of calcium-sensitive receptors (CaSR) on the expression of endothelial nitric oxide synthase (eNOS) and the concentration of nitric oxide (NO) in a neonatal mouse model of persistent pulmonary hypertension (PPH). METHODS: Eighty neonatal C57BL/6 mice were randomly divided into control, PPH, agonist and antagonist groups. The control group was exposed to air, and the other three groups were exposed to 12% oxygen. The agonist and antagonist groups were intraperitoneally injected with a CaSR agonist (GdCl3 16 mg/kg) and a CaSR antagonist (NPS2390, 1 mg/kg), respectively, while the PPH and control groups were intraperitoneally injected with normal saline instead. All mice were treated for 14 days. Alveolar development and pulmonary vessels were assessed by hematoxylin-eosin staining. The protein and mRNA expression of eNOS and its localization in lung tissues were determined by Western blot, qRT-PCR and immunohistochemistry. The levels of brain natriuretic peptide (BNP) and NO in lung homogenate were determined using ELISA. RESULTS: Compared with the control group, the PPH and agonist groups showed significant increases in alveolar mean linear intercept, the percent wall thickness of pulmonary arterioles, right to left ventricular wall thickness ratio (RV/LV) and BNP concentration, but a significant reduction in radial alveolar count (P<0.05). The antagonist group had significant improvements in all the above indices except RV/LV compared with the PPH and agonist groups (P<0.05). Compared with those in the control group, the protein and mRNA expression of eNOS and NO concentration were significantly increased in the PPH group and increased more significantly in the agonist group, but were significantly reduced in the antagonist group (P<0.05). CONCLUSIONS: CaSR plays an important role in the development of PPH in neonatal mice, possibly by increasing eNOS expression and NO concentration.

[Effects of calcium-sensitive receptors on 11ß-hydroxysteroid dehydrogenase type 2 and cortisol in neonatal mice with persistent pulmonary hypertension].

OBJECTIVE: To investigate the effects of calcium-sensitive receptors (CaSR) on the expression of 11ß-hydroxysteroid dehydrogenase type 2 (11ß-HSD2) and cortisol concentration in a neonatal mouse model of persistent pulmonary hypertension (PPH). METHODS: Fifty-six newborn C57BL/6 mice were randomly divided into a control group (n=14), a PPH group (n=14), an agonist group (n=14), and an inhibitor group (n=14). The mice in the PPH, agonist, and inhibitor groups were exposed to a 12% oxygen concentration, and the agonist group and inhibitor group were given CaSR agonist (GdCl3, 16 mg/kg) and CaSR antagonist (NPS2390, 1 mg/kg) intraperitoneally once a day, respectively. The mice in control group were exposed to air, and then injected with an equal volume of normal saline as those in the PPH group every day. All mice were treated for 14 days. Morphological examination of heart and lung tissues was performed using hematoxylin-eosin staining. The expression levels of 11ß-HSD2 mRNA and 11ß-HSD2 protein in lung tissues were measured by qRT-PCR and Western blot respectively. Brain natriuretic peptide (BNP) and cortisol levels in lung tissues were determined using ELISA. RESULTS: Compared with the control group, the PPH group had significantly increased pulmonary artery wall thickness (WT%), ratio of right to left ventricular thickness (RV/LV), alveolar mean linear intercept, and BNP concentration and a significantly reduced radial alveolar count (P<0.05); compared with the PPH group, the agonist group showed significant increases in WT% and BNP concentration, while the inhibitor group showed significant reductions in the two indicators (P<0.05). Compared with the control group, the PPH group showed significant reductions in the expression levels of 11ß-HSD2 mRNA and 11ß-HSD2 protein, but a significant increase in cortisol concentration (P<0.05); compared with the PPH group, the agonist group had significantly lower expression levels of 11ß-HSD2 mRNA and 11ß-HSD2 protein, but a significant higher cortisol concentration, while the inhibitor group showed opposite changes in these indicators (P<0.05). CONCLUSIONS: CaSR may control the development and progression of PPH in newborn mice by regulating the expression of 11ß-HSD2 and cortisol concentration.

[Seasonal variation of soil respiration and its components in tropical rain forest and rubber plantation in Xishuangbanna, Yunnan].

By using trenching method and infrared gas analyzer, this paper studied the seasonal variation of soil respiration (SR), including root respiration (RR) and heterotrophic respiration (HR), in tropical seasonal rain forest (RF) and rubber (Hevea brasiliensis) plantation (RP) in Xishuangbanna of Yunnan, China. The results showed that the SR and HR rates were significantly higher in RF than in RP (P < 0.01), while the RR rate had less difference between the two forests. Soil temperature and moisture were the key factors affecting the SR, RR and HR. The SR and HR rates in the two forests were rainy season > dry-hot season > foggy season, but the RR rate was rainy season > foggy season > dry-hot season in RF, and foggy season > rainy season > dry-hot season in RP. The contribution of RR to SR in RF (29%) was much lower than that in RP (42%, P < 0.01), while the contribution of HR to SR was 71% in RF and 58% in RP. When the soil temperature at 5 cm depth varied from 12 degrees C to 32 degrees C, the Q10 values for SR, HR, and RR rates were higher in RF than in RP. HR had the highest Q10 value, while RR had the lowest one.