BACKGROUNDHuman urotensin II (UII) is the most potent mammalian vasoconstrictor identified so far. Our previous study showed that UII is a potent mitogen of airway smooth muscle cells (ASMC) inducing ASMC proliferation in a dose-dependent manner. The signal transduction pathway of UII mitogenic effect remains to be clarified. This study was conducted to investigate the signal transduction pathway in the proliferation of ASMC induced by UII.

METHODSIn primary cultures of rat ASMCs, activities of protein kinase C (PKC), mitogen-activated protein kinase (MAPK) and calcineurin (CaN) induced by UII were measured. The effect of CaN on PKC and MAPK was studied by adding cyclosporin A (CsA), a specific inhibitor of CaN. Using H7 and PD98059, inhibitors of PKC and MAPK, respectively, to study the effect of PKC and MAPK on CaN. The cytosolic free calcium concentration induced by UII was measured using Fura-2/AM.

RESULTSUII 10(-7) mol/L stimulated ASMC PKC and MAPK activities by 44% and 24% (P < 0.01), respectively, after incubating for 20 minutes. It increased CaN activity in a time-dependent manner, being 1.68 times as that of control for 24 hours (P < 0.01). It promoted the cytosolic free calcium concentration increase of 18% (P < 0.01). CsA 10(-6) mol/L and H7 50 micromol/L inhibited UII-stimulated CaN activity by 45% (P < 0.01) and 21% (P < 0.05), respectively, while PD98059 50 micromol/L had no effect on CaN activity (P > 0.05). CsA 10(-6) mol/L inhibited UII-stimulated PKC activity by 14% (P < 0.05), while having no effect on MAPK activity (P > 0.05).

CONCLUSIONSUII increases cytosolic free calcium concentration and activates PKC, MAPK and CaN. The signal transduction pathway between PKC and CaN has cross-talk.

Animals ; Calcineurin ; metabolism ; Cells, Cultured ; Enzyme Activation ; Mitogen-Activated Protein Kinases ; metabolism ; Mitogens ; pharmacology ; Myocytes, Smooth Muscle ; cytology ; Protein Kinase C ; metabolism ; Rats ; Signal Transduction ; physiology ; Trachea ; cytology ; Urotensins ; pharmacology

OBJECTIVETo study the effects of intestinal microflora alteration on specific and nonspecific immune function and hematopoietic function of mice.

METHODSSixty BALB/C mice were divided at random into two groups, experimental group and control group, with 30 mice in each. The mice in the experimental group were given kanamycin 50 mg while those in the control group were given distilled water intragastrically everyday for consecutive 10 days. After the 10 day treatment all the mice were sacrificed, and the cecal contents were collected for quantitative analysis of the intestinal bacterial flora. Certain indexes of immune function, including phagocytosis rate of macrophages, number of T lymphocytes positively stained by esterase and serum interleukin 2 (IL-2) content, and the weight of the spleen, granulocyte-macrophage colony stimulating factor etc. as indexes of hematopoietic function were determined.

RESULTSIn the group, the quantity of Enterobacteriaceae, Enterococcus, Bifidobacterium and Lactobacillus were significantly lower than that in the control group (P < 0.01). The number of PFC (plaque forming cells), the phagocytosis rate of macrophage, the number of T lymphocytes with positive NANE staining, the level of IL-2 significantly decreased when compared with that in the control group (P < 0.01). The weight of the spleen in the experimental group decreased when compared with that in the control group (P < 0.01). Levels of IL-3, GM-CSF, the total number of WBC and the proportion of neutrophil remarkably decreased as compared to that in the control group (P < 0.01). Analysis of the correlations between normal microflora, immunologic and hematopoietic indexes showed that marked positive correlations between the quantity of Bifidobacteria and each immune index including the levels of IL-3 and GM-CSF. There was a positive correlation between IL-2 and IL-3, IL-2 and GM-CSF as well.

CONCLUSIONThe application of antibiotics may cause changes in the structure and quantity of intestinal microflora. The dysbacteriosis may decrease the immune function of organism. The dysbacteriosis may decrease the hemopoietic function. The dysbacteriosis, the decrease in immune and hematopoietic function may affect one another. The balance in microecosystem should be emphasized and antibiotics should be applied rationally to reduce the side effects such as dysbacteriosis.

Animals ; Anti-Bacterial Agents ; pharmacology ; Esterases ; biosynthesis ; Feces ; microbiology ; Granulocyte-Macrophage Colony-Stimulating Factor ; analysis ; Interleukin-2 ; blood ; Intestines ; drug effects ; microbiology ; Kanamycin ; pharmacology ; Macrophages ; drug effects ; physiology ; Mice ; Mice, Inbred BALB C ; Models, Animal ; Organ Size ; Phagocytosis ; drug effects ; Spleen ; drug effects ; pathology ; T-Lymphocytes ; drug effects ; metabolism

In this study, we observed the levels of adrenomedullin (ADM) and proadrenomedullin N-terminal 20 peptide (PAMP) in myocardium and aorta of spontaneously hypertensive rats (SHRs) in comparison with Wistar-kyoto (WKY) rats. Contents of ADM and PAMP were measured by radioimmunoassay (RIA) in plasma, myocardium and aorta. The amount of Pro-ADM mRNA of myocardium and aorta was determined by competitive quantitative reverse transcription polymerase chain reaction (RT-PCR). In SHRs the amounts of Pro-ADM mRNA of myocardium and aorta were 66.7% (P<0.01) and 73% (P<0.01) higher than those in WKY rat, respectively. In SHRs, the levels of ADM in plasma, myocardium and aorta were 29%, 76.7% and 79% (all P<0.01) higher than those in WKY rats, respectively. The level of PAMP in SHRs was increased by 42.5% in plasma (P<0.01), 47.2% in myocardium (P<0.0.1) and 27.3% in aorta (P<0.05) compared to WKY rats, respectively. In addition, the ratio of ADM content to PAMP content in SHRs group was increased compared with that in WKY group (2.0+/-0.25 vs 1.64+/-0.3 and 2.2+/-0.18 vs 1.56+/-0.28, in myocardium and aorta, respectively, P<0.01). These results suggest that ProADM gene expression is up-regulated and the increase in ADM and PAMP is different in SHRs. The significance of inconsistency of increase in ADM and PAMP in SHRs needs to be further investigated.
Adrenomedullin ; genetics ; metabolism ; Animals ; Aorta ; metabolism ; Female ; Male ; Myocardium ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Inbred SHR ; Rats, Inbred WKY ; Up-Regulation

AIM AND METHODSTo observe the effect of myocardial mitochondrial L-arginine (L-Arg)/nitric oxide (NO) system on mitochondrial Ca2+ transport by using purified rat mitochondria and incubation of them in vitro.

RESULTSCompared with control group, incubation of mitochondria with L-Arg (10(-4) mol/L, NO substrate) or sodium nitroprusside (5 x 10(-7) mol/L, the donor of exogenous NO, SNP) increased significantly mitochondrial NO2- (66% and 89%, P < 0.01), respectively, and decreased the Ca2+ content (40% and 54%, P < 0.01). After L-Arg or SNP treatment, mitochondrial Ca2+ uptake were decreased by 67% and 85%, respectively (P < 0.01), vs control. The rate of mitochondrial Ca2+ release decreased by 11% and 8%, respectively (P < 0.01). When L-NAME (NO synthase inhibitor) was incubated with mitochondria and the L-Arg together, it inhibited the effects of L-Arg, NO2 on the mitochondrial NO2 formation, Ca2+ content descending, and decrease of Ca2+ uptake and release.

CONCLUSIONThe data suggest that myocardial mitochondrial L-Arg /NO systems take part in the regulation of cardiomyocytes Ca2+ transportation.

Animals ; Arginine ; metabolism ; Biological Transport ; Calcium ; metabolism ; Female ; Male ; Mitochondria, Heart ; metabolism ; Myocytes, Cardiac ; metabolism ; Nitric Oxide ; metabolism ; Nitric Oxide Synthase ; metabolism ; Rats ; Rats, Wistar

AIMThe characteristics of ryanodine receptor in rat cardiac sarcoplasmic reticulum (SR) and nuclear envelope (NE) were studied.

METHODSVelocity and isopyknic gradient centrifugation was employed to fractionate rat SR and NE. Ryanodine receptor was assayed with [3H] ryanodine saturate binding to the preparations.

RESULTSThe maximal binding (Bmax) and dissociating constant (Kd) of ryanodine receptor in rat cardiac NE were, 1.7% and 60% of those in SR respectively. Phosphorylation in vitro by PKA and PKC increased Bmax of the receptors in SR by 372% and 121%, and augmented those in NE by 221% and 306%, without any effects on Kd.

CONCLUSIONRyanodine receptors were present in rat myocardial NE, with lower density and higher affinity than those located in SR, which can be activated by PKA and PKC.

Animals ; Calcium ; metabolism ; Kinetics ; Myocardium ; metabolism ; Nuclear Envelope ; metabolism ; physiology ; Phosphorylation ; Rats ; Rats, Sprague-Dawley ; Ryanodine ; metabolism ; Ryanodine Receptor Calcium Release Channel ; metabolism ; Sarcoplasmic Reticulum ; metabolism ; physiology

OBJECTIVETo observe the alterations of taurine transport, taurine transporter (TAUT) and cysteine sulfinate decarboxylase (CSD) mRNA in the calcification of myocardial cells in vitro.

METHODS3H-taurine measured the amount of taurine uptake. TAUT and CSD mRNA consents were measured using competitive quantitative RT-PCR in cultured and calcified myocardial cells.

RESULTSIn calcification of myocardial cells, taurine concentration was decreased by 27% (P < 0.05), taurine uptake was markedly reduced, Vmax reduced by 39% (P < 0.01), there were no statistical significance of Km values between the two groups. TAUT mRNA decreased by 45% (P < 0.01), but CSD mRNA increased by 25% (P < 0.05).

CONCLUSIONSThe data suggest that there were impediment of taurine transport in calcification of myocardial cells, as TAUT mRNA level was decreased, but CSD mRNA concentration was improved.

Animals ; Biological Transport ; Calcinosis ; metabolism ; pathology ; Calcium ; metabolism ; Carboxy-Lyases ; metabolism ; Cells, Cultured ; Myocytes, Cardiac ; metabolism ; pathology ; RNA, Messenger ; metabolism ; Rats ; Taurine ; biosynthesis ; genetics ; metabolism

The purpose of the present study was to explore the expression changes of intermedin/adrenomedullin 2 (IMD/ADM2), a novel small molecular bioactive peptide, and its receptors, calcitonin receptor-like receptor (CRLR) and receptor activity modifying proteins (RAMP1, RAMP2, RAMP3) in the right ventricle of rats with chronic hypoxia-induced pulmonary hypertension. Twenty male Sprague-Dawley rats were randomly divided into 4-week hypoxia group and normal control group (each n=10). The rats in hypoxia group were placed in an isobaric hypoxic chamber, in which O(2) content was maintained at 9%-11% by delivering N(2), and CO(2) content was maintained at <3% for 4 weeks (8 h/d, 6 d/week). The rats in the control group were housed in room air. The protein levels of IMD/ADM2 and adrenomedullin (ADM) in blood plasma and right ventricular tissue were measured by radioimmunoassay. The mRNA expressions of IMD/ADM2, ADM and their receptors CRLR, RAMP1, RAMP2, RAMP3 in right ventricular tissue were determined by reverse transcription-polymerase chain reaction (RT-PCR). The results showed that the ratio of right ventricle weight to left ventricle plus septum weight [RV/(LV+S)] and mean pulmonary arterial pressure (mPAP) were higher in hypoxia group than those in the control group (all P<0.01), suggesting that the rat model of pulmonary hypertension was successfully established. However, the mean carotid arterial pressure (mCAP) between the two groups had no significant difference. Compared with that in the control group, ADM contents in plasma and right ventricular tissue in hypoxia group increased by 1.26 and 1.68 folds (all P<0.01), respectively. Likewise, IMD/ADM2 contents in blood plasma and right ventricular tissue in hypoxia group increased by 0.90 and 1.19 folds (P<0.01), respectively, compared with that in the control group. The data of RT-PCR showed that mRNA levels of ADM, IMD/ADM2 and RAMP2 in hypoxia group increased by 155.1% (P<0.01), 80.9% (P<0.01) and 52.9% (P<0.05), respectively, compared with those in the control group. There were no significant differences in mRNA expressions of CRLR, RAMP1 and RAMP3 between the two groups (all P>0.05). Taken together, the results show that the level of IMD/ADM2 increases in the rats with chronic hypoxia-induced pulmonary hypertension.
Adrenomedullin ; metabolism ; Animals ; Calcitonin Receptor-Like Protein ; metabolism ; Heart Ventricles ; metabolism ; Hypertension, Pulmonary ; etiology ; metabolism ; physiopathology ; Hypoxia ; complications ; Male ; Neuropeptides ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptor Activity-Modifying Proteins ; metabolism

AIMTo investigate the changes and probable roles of adrenomedullin2/intermedin (AIDM2/IMD), a novel micromolecular bioactive peptide, in the lungs of rats with chronic hypoxic pulmonary hypertension.

METHODSTwenty male SD rats were randomly divided into normal control group (NC) and normobaric hypoxia group (4H). The protein levels of ADM and ADM2/IMD) in the plasma and lung were measured by radioimmunoassay and immunohistochemistry. The mRNA expressions of ADM, ADM2/IMD and their receptors C (RLR, RAMP1, RAMP2 and RAMP3 in the lung tissue were determined by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS(1) The rat model of chronic pulmonary hypertension was confirmed by the increased mean pulmonary arterial pressure (mPAP) and weight ratio of right ventricle to left ventricle plus septum [RV/(LV + S)] in 4H group compared to NC group. (2) The concentrations of ADM in the plasma and lung homogenate of 4H group were 2.3 and 3.2 folds of NC group, respectively (all P < 0.01). The levels of ADM2/IMD were higher 89.6% and 45.0% in the plasma and lung homogenate of 4H group than those of NC group (respectively, P < 0.01, P < 0.05). (3) The mRNA expressions of ADM2/IMD and ADM in the lung of 4H group were up-regulated (respectively, P < 0.01, P < 0.05 vs. NC group). The expressions of CRLR and RAMP1 mRNAs were down-regulated (all P < 0.01 vs. NC group), while the levels of RAMP2 and RAMP3 mRNAs were no significant difference between the two groups. (4) The strong ADM2/IMD immunostaining was detected in the endothelial and adventitial cells of the rat pulmonary arteriole.

CONCLUSIONADM2/IMD, like its paralog ADM, might be closely related to the chronic hypoxic pulmonary hypertension in rats. The disorders of the gene expression and/or the synthesis and metabolism of ADM2/IMD and its receptor CRLR/RAMP1 possibly take part in the pathogenesis of chronic hypoxic pulmonary hypertension in rats.

Adrenomedullin ; metabolism ; Animals ; Hypertension, Pulmonary ; etiology ; metabolism ; Hypoxia ; complications ; metabolism ; Lung ; metabolism ; Male ; Neuropeptides ; metabolism ; Rats ; Rats, Sprague-Dawley

The alterations of taurine transport and the expression of taurine transporter (TAUT) mRNA in myocardium and aortic wall were investigated in spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. It was demonstrated that plasma taurine concentration and taurine release from myocardium and aortic wall in SHR were higher than those in WKY rats, whereas taurine content, taurine uptake and TAUT mRNA in myocardium and aortic wall of SHR were lower than those of WKY rats. In SHR, the maximal velocity (V(max)) of taurine transportation in myocardium and aortic wall was lower by 24% (P<0.05) and 35% (P<0.05) than that in WKY, their michaelis constants (Km) values were higher by 16% (P<0.05) and 39% (P<0.05), respectively. The results suggest that there is dysfunction of taurine transport in myocardium and aortic wall in SHR, which may be partly resulted from the decrease of TAUT activity and affinity, and down-regulation of TAUT gene expression.
Animals ; Blood Vessels ; metabolism ; physiopathology ; Carrier Proteins ; metabolism ; Heart ; physiopathology ; In Vitro Techniques ; Male ; Myocardium ; metabolism ; Rats ; Rats, Inbred SHR ; Rats, Inbred WKY ; Taurine ; metabolism

To explore the changes in adrenomedullin (ADM) and receptor activity-modifying protein 2 (RAMP2) mRNA in myocardium and vessels in hypertension, a hypertensive rat model was prepared by administering L-NNA. Contents of ADM in plasma, myocardium and vessels were measured by radioimmunoassay (RIA). The levels of pro-ADM mRNA of myocardium and vessels were determined by competitive quantitative RT-PCR. The results showed that L-NNA induced hypertension and cardiomegaly. The ratio of heart to body weight increased by 35.5% (P<0.01). In hypertensive rats the ir-ADM in plasma, myocardium and vessels was increased by 80%, 72% and 57% (P<0.01), respectively compared with the control. The amounts of ADM mRNA in myocardium and vessels were increased by 50% and 109.2% (P<0.05), respectively, and the amounts of RAMP2 mRNA was increased by 132% and 87% (P<0.01), respectively, compared with control. The levels of ADM in myocardium and vessels were positively correlated with RAMP2 mRNA, the correlation coefficients were 0.741 and 0.885 (P<0.01), respectively. The results obtained indicate that in hypertensive rats, ADM is elevated in plasma, myocardium and ves-myocardium and vessel, and ADM and RAMP2 mRNA are up-regulated in myocardium and vessel. The ADM/RAMP2 system may play an important role in the pathogenesis of hypertension.
Adrenomedullin ; metabolism ; Animals ; Cardiomegaly ; chemically induced ; metabolism ; Hypertension ; chemically induced ; metabolism ; Myocardium ; metabolism ; Nitroarginine ; pharmacology ; RNA, Messenger ; Rats ; Receptor Activity-Modifying Protein 2 ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Up-Regulation