The aim of this study was to investigate the effect of interleukin 6 (IL-6) on the contraction of colon longitudinal muscle strips in rats with acute pancreatitis (AP) and its underlying mechanism. Rat AP model was established by combined injection (i. p.) of ceruletide and lipopolysaccharide. The effect of IL-6 on spontaneous contraction of longitudinal smooth muscle strips of rat colon was observed by biological function experiment system. The level of serum IL-6 was detected by ELISA, the expression and distribution of IL-6 in colon were observed by histochemical staining, and the effect of IL-6 on L-type calcium channel in colon smooth muscle cells was observed by whole cell patch clamp technique. The results showed that, compared with the control group, AP group exhibited reduced contractile amplitude and longer contraction cycle of colon smooth muscle strips. IL-6 prolonged the contraction cycle of colon smooth muscle strips, but did not affect their spontaneous contraction amplitude. Serum IL-6 concentration in AP group was significantly higher than that in control group (P > 0.05). IL-6 was diffusely distributed in the colon of the control group, but the expression of IL-6 was significantly up-regulated in the colon gland, mucosa and submucosa of the AP group. IL-6 significantly decreased the peak current density of L-type calcium channel in rat colon smooth muscle cells. These results suggest that the colon motility of AP rats is weakened, and the mechanism may be that up-regulated IL-6 inactivates L-type voltage-dependent calcium channels, and then inhibits the contraction of colon longitudinal smooth muscle.
Animals ; Calcium Channels, L-Type ; metabolism ; Colon ; Interleukin-6 ; metabolism ; Muscle Contraction ; Muscle, Smooth ; physiopathology ; Pancreatitis ; physiopathology ; Rats

To investigate the time-course changes of myogenic tone in mesenteric small artery (MSA) of spontaneously hypertensive rat (SHR), thirty-two 7-week aged SHR rats were randomly divided into four groups (8, 16, 24, 32 weeks of age), and 32 sex- and age-matched Wistar-Kyoto (WKY) rats were assigned to control groups (CON). On the day of the study, segments of MSA were isolated and then cannulated to the two pipettes. Vascular diameters in response to the increased intraluminal pressure (from 0 mmHg to 150 mmHg, by 25 mmHg steps) of isolated MSA under no-flow conditions were recorded by a Pressure Myograph System both in physiologic salt solution (PSS) (active diameter, Da) and calcium-free PSS (passive diameter, Dp). The myogenic tone was calculated by (Dp - Da)/Dp × 100%. The tail artery pressure and vascular myogenic tone in SHR rats were significantly higher than those of the CON rats. Before 24 weeks, the vascular myogenic tone of MSA in SHR group increased monotonically, but at the end of 32 weeks, the vascular myogenic tone decreased in comparison with that in 24-week group, but was significantly higher than that in CON group. The tail artery pressure in SHR group slowly increased monotonically with increasing weeks of age, and the tail arterial pressure in 32-week group remained significantly higher than that in 24-week group. Vascular myogenic tone may participate in the whole process of hypertension. Early in the development of hypertension, because of the compensatory role of vascular tone, the vascular function has been partially compensated, thus guaranteeing adequate blood supply to organs. Late in the development of hypertension, because of the decompensation of myogenic tone, the vascular function is damaged, leading to the occurrence of severe vascular disease.
Animals ; Blood Pressure ; Hypertension ; physiopathology ; Male ; Mesenteric Arteries ; physiopathology ; Muscle Tonus ; Muscle, Smooth, Vascular ; physiopathology ; Random Allocation ; Rats ; Rats, Inbred SHR ; Rats, Inbred WKY ; Time Factors ; Vasoconstriction ; physiology

The aim of the present study was to investigate the changes of lymphatic contraction after hemorrhagic shock in vitro and the underlying role of nitric oxide (NO). Rat thoracic duct segments were isolated at 0, 0.5, 1, 2 and 3 h after hemorrhagic shock. Using Pressure Myograph System, we determined contraction frequency (CF), end systolic diameter (ESD), end diastolic diameter (EDD) and passive diameter (PD) of isolated rat lymphatics under different transmural pressures (1, 3, 5, 7 and 9 cmH(2)O), then calculated contraction amplitude (CA), tonic index (TI) and fractional pump flow (FPF) of lymphatics. The results showed that in several transmural pressures, lymphatic CF, TI and FPF were significantly higher in shock 0 h and shock 0.5 h groups than those in control group (sham operation group). With the development of shock, lymphatic CF, TI and FPF decreased significantly in shock 2 h and shock 3 h groups compared with those in control group. We further discovered the role of NO in the changes of lymphatic contraction after hemorrhagic shock. Under 3 cmH(2)O transmural pressure, the changes of lymphatic contraction in shock 0.5 h and shock 2 h groups were analyzed following the incubation with several NO-related drugs alone or in combination. And the results showed that NO donor L-Arg reduced CF, TI and FPF in shock 0.5 h group to the control levels, while soluble guanylate cyclase inhibitor ODQ suppressed the effect of L-Arg. Moreover, NOS inhibitor L-NAME elevated the CF, TI and FPF of 2 h shock lymphatics to the control levels, while phosphodiesterase inhibitor aminophylline (AP) suppressed the effect of L-NAME. These results suggest that the lymphatic contractile activity exhibits a biphasic change during hemorrhagic shock, increasing in early phase and declining in later stage. And NO plays a major regulating role in the biphasic change of lymphatic contraction in hemorrhagic shock rats via cGMP pathway.
Animals ; Cyclic GMP ; metabolism ; In Vitro Techniques ; Male ; Muscle Contraction ; Muscle, Smooth ; physiopathology ; Nitric Oxide ; physiology ; Random Allocation ; Rats ; Rats, Wistar ; Shock, Hemorrhagic ; physiopathology ; Thoracic Duct ; physiopathology ; Time Factors

OBJECTIVETo investigate the changes of open probability (Po) of large conductance Ca(2+)-activated K(+) channel (BK channel) in diabetic coronary smooth muscle cells and elucidate the underlying cellular electrophysiology mechanisms of coronary dysfunction.

METHODSRat coronary smooth muscle cells were isolated from control group and diabetic group. BK single channel currents were recorded by patch clamp technique in inside-out configuration. Open probabilities were calculated and compared between two groups. After exposure to DHS-1, a specific BK channel activator, Po at 0.2 and 1 µmol/L free Ca(2+) were compared between control and diabetic groups.

RESULTSIn the presence of 0.2 µmol/L free Ca(2+), the Po at baseline was significantly lower in diabetic rats than in control rats (0.0032 ± 0.0012 vs. 0.095 ± 0.036, P < 0.05). Cytoplasmic application of DSH-1 significantly increased the Po to 0.335 ± 0.096 (P < 0.05 vs. baseline) in control rats, whereas DSH-1 had no effect in diabetic rats (Po = 0.022 ± 0.018, P > 0.05 vs. baseline). In the presence of 1 µmol/L free Ca(2+), the Po at baseline was also significantly lower in diabetic rats than in control rats (0.210 ± 0.055 vs. 0.458 ± 0.077, P < 0.05). Cytoplasmic application of DHS-1 further robustly enhanced Po to 0.823 ± 0.019 (P < 0.05 vs. baseline) in control rats and to 0.446 ± 0.098 in diabetic rats (P < 0.05 vs. baseline of diabetic rats; P < 0.05 vs. control rats with DHS-1).

CONCLUSIONThe decrease of Po of BK single channel in coronary smooth muscle cells may be a potential cause for coronary dysfunction in diabetic rats.

Animals ; Coronary Vessels ; metabolism ; physiopathology ; Diabetes Mellitus, Experimental ; metabolism ; physiopathology ; Large-Conductance Calcium-Activated Potassium Channels ; metabolism ; Male ; Muscle, Smooth, Vascular ; cytology ; physiopathology ; Myocytes, Smooth Muscle ; metabolism ; Patch-Clamp Techniques ; Rats ; Rats, Sprague-Dawley

AIMTo investigate the effect of protein kinase C regulating pulmonary arterial remodeling in chronic hypoxic rats.

METHODSElectron microscope, radioactivity, immunohistochemistry and image analyser were used.

RESULTS(1) Mean pulmonary arterial pressure (mPAP) and weight ratio of RV to LV + S were significantly higher than that of control group (P < 0.01). (2) WA/TA and SMC were significantly higher than that of control group (P < 0.01). Electron microscopy showed the proliferation of smooth muscle cells and the disposition of collagenous fiber in pulmonary arterioles induced by hypoxia. (3) The total, cytosolic, particulate fraction PKC activity and the ratio of particulate fraction to total PKC activity were significantly higher than that of control group (P < 0.01). (4) Expression of PKC, collagen I were significantly higher than that of control group (P < 0.01), the difference of collagen III was not significant between two groups (P > 0.05). (5) There were good correlation between the total, particulate fraction PKC activity, the ratio of particulate fraction to total PKC activity, expression of PKC and SMC, collagen I in pulmonary arterioles.

CONCLUSIONThe PKC regulates the proliferation of pulmonary artery smooth muscle cells and expression of pulmonary arterial collagen in chronic hypoxic rats, which may play an important role in the pathogenesis of pulmonary hypertension and structural remodeling of pulmonary arteries.

Animals ; Collagen ; metabolism ; Female ; Hypertension, Pulmonary ; metabolism ; physiopathology ; Hypoxia ; metabolism ; physiopathology ; Male ; Myocytes, Smooth Muscle ; metabolism ; Protein Kinase C ; metabolism ; Pulmonary Artery ; physiopathology ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo assess the clinical significance of electrophysiological tests of bulbocavernosus reflex (BCR), ischiocavernosus reflex (ICR) and pudenda somatosensory evoked potential (PSEP) for patients with erectile dysfunction (ED).

METHODSElectrophysiological tests of BCR, ICR and PSEP were performed for 232 ED patients with IIEF-5 scores of 2-20 (10.39 +/- 5.52), another 21 normal volunteer controls underwent the same tests, and the results were compared.

RESULTSAbnormal results, such as prolonged and advanced latencies, were found in 94 (40.5%) of the patients, which suggested neurotic ED with different degrees of cauda equine nerve injuries.

CONCLUSIONElectrophysiological tests of BCR, ICR and PSEP can objectively reveal the functional state of the cauda equine nerve and offer an important support to the diagnosis of nerve-mediated ED.

Adult ; Aged ; Case-Control Studies ; Electrophysiology ; Erectile Dysfunction ; physiopathology ; Evoked Potentials, Somatosensory ; Humans ; Male ; Middle Aged ; Muscle, Smooth ; physiopathology ; Penis ; innervation ; physiopathology ; Reflex ; physiology

Cell Nucleus Division ; Cyclin-Dependent Kinase Inhibitor p16 ; metabolism ; Diagnosis, Differential ; Female ; Humans ; Leiomyoma ; metabolism ; pathology ; physiopathology ; Smooth Muscle Tumor ; metabolism ; pathology ; physiopathology ; Uterine Neoplasms ; metabolism ; pathology ; physiopathology

The aim of the present study was to investigate the effects of acute hypoxia on the electrophysiological properties of vascular smooth muscle cells (VSMCs) in arteriole. Guinea-pig anterior inferior cerebellar artery (AICA) segments were isolated, and outer layer connective tissue was removed by collagenase A digestion and microforceps. By perfusion with physical saline solution containing no glucose and low oxygen, VSMC model of acute hypoxia was established. The model was studied by whole-cell patch clamp recording technique. Results were shown as below: (1) Acute hypoxia induced an outward current with amplitude of (36.4 ± 9.2) pA at holding potential of -40 mV, and the rest potential (RP) of the VSMCs was hyperpolarized from (-33.2 ± 1.9) mV to (-38.4 ± 1.5) mV. Acute hypoxia increased the outward current of VSMCs in a voltage-dependent manner, this enhancing effect being more pronounced at potentials ranging from 0 to +40 mV. The whole-cell membrane current of VSMCs induced by step command (+40 mV) increased from (650 ± 113) pA to (1 900 ± 197) pA. In the presence of 1 mmol/L tetraethylammonium (TEA), the enhancement of the VSMC membrane current by acute hypoxia was significantly reduced. (2) Acute hypoxia increased the membrane resistance (R(input)) of the VSMCs in AICA from (234 ± 63) MΩ to (1 211 ± 201) MΩ, and decreased the membrane capacitance (C(input)) from (279.3 ± 83.2) pF to (25.4 ± 1.9) pF. In the presence of 30 μmol/L 18β-glycyrrhetinic acid (18βGA) and 10 mmol/L TEA, the effects of acute hypoxia on the membrane current of VSMCs were nearly abolished. These results suggest that acute hypoxia causes vascular hyperpolarization and vasodilation, possibly by activating big conductance Ca(2+)-activated K(+) channels (BK(Ca)) of the VSMCs, and inhibits gap junctions between VSMCs, thus improving microcirculation and localizing the hypoxia-induced damage.
Animals ; Arteries ; physiopathology ; Cerebellum ; blood supply ; Female ; Gap Junctions ; metabolism ; physiology ; Guinea Pigs ; Hypoxia ; physiopathology ; In Vitro Techniques ; Male ; Muscle, Smooth, Vascular ; cytology ; metabolism ; physiology ; Myocytes, Smooth Muscle ; metabolism ; physiology ; Patch-Clamp Techniques ; Potassium Channels ; physiology

Pulmonary arterial hypertension is associated with profound vascular remodeling and alterations in Ca2+ homeostasis in pulmonary arterial smooth muscle cells (PASMCs). Recent studies show that canonical transient receptor potential channel 6 (TRPC6) genes, which encode receptor-operated cation channels (ROCC) in PASMCs, play an important role in Ca2+ regulation and cell proliferation. The aim of the present study was to investigate the role of TRPC6 in monocrotaline (MCT)-induced pulmonary artery hypertension. Sprague-Dawley rats were randomly divided into normal control group and MCT group. In MCT group, pulmonary arterial hypertension was induced by a single intraperitoneal injection of MCT at a dose of 60 mg/kg. After 3 weeks, the right ventricular systolic pressure (RVSP) and the right ventricular mass index (RVMI) were measured. The lung sections were stained by HE and observed under light microscope. Semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) and Western blot were performed to detect the expression of TRPC6 in rat pulmonary arteries. The 1-oleoyl-2-acetyl-sn-glycerol (OAG)-induced contractile tension of pulmonary arteries were measured by vascular ring tension analysis and the intracellular Ca2+ concentration ([Ca2+](i))of PASMCs was monitored using Fluo3-AM assay. The results showed that RVSP and RVMI markedly elevated in MCT group (P<0.01) in comparison to CON group. The thickness of pulmonary vascular smooth muscles was increased and the inner diameter of pulmonary arteries was diminished in MCT group. Though there was no significant difference in the levels of mRNA and protein of TRPC6 between CON and MCT groups, the application of OAG, which can directly activate ROCC, induced greater contraction tension of pulmonary arteries (P<0.01) and more Ca2+ entries in PASMCs (P<0.05) in MCT group compared to those in control group. These results indicate that MCT induces pulmonary artery hypertension and thus remodeling of the right ventricle and pulmonary arteries in rats. The expression of mRNA and protein of TRPC6 is not potentiated by MCT, but the TRPC6/ROCC-mediated Ca2+ entry in PASMCs and vascular tone of pulmonary arteries are significantly increased with MCT treatment.
Animals ; Calcium ; metabolism ; Hypertension, Pulmonary ; chemically induced ; metabolism ; physiopathology ; Male ; Monocrotaline ; pharmacology ; Muscle, Smooth, Vascular ; cytology ; metabolism ; Myocytes, Smooth Muscle ; cytology ; metabolism ; Pulmonary Artery ; cytology ; metabolism ; physiopathology ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; TRPC Cation Channels ; genetics ; metabolism

Hypoxia-induced 15-hydroxyeicosatetraenoic acid (15-HETE) is an essential mediator to constrict pulmonary arteries (PA). The signaling pathway involved in 15-HETE-induced PA vasoconstriction remains obscure. The aim of the present study was to test the hypothesis that hypoxic PA constriction induced by 15-HETE was possibly regulated by the extracellular signal-regulated kinase-1/2 (ERK1/2) pathway. PA ring tension measurement, Western blot and immunocytochemistry were used in the study to determine the possible role of ERK1/2 in 15-HETE-induced PA vasoconstriction. The organ bath for PA rings tension study was employed. Adult male Wistar rats were raised in hypoxic environment with fractional inspired oxygen (FIO2, 0.12) for 9 d. PA 1~1.5 mm in diameter were dissected and cut into 3 mm long rings for tension study. ERK1/2 up-stream kinase (MEK) inhibitor PD98059, which blocks the activation of ERK1/2, was used. The results showed that pretreatment of PD98059 significantly blunted 15-HETE-induced PA vasoconstrictions in the rings from hypoxic rat. Moreover, in endothelium-denuded rings, PD98059 also significantly attenuated 15-HETE-induced vasoconstriction. Phosphorylation of ERK1/2 in pulmonary arterial smooth muscle cells (PASMCs) of rat was enhanced evidently when stimulated by 15-HETE. Thus, the data suggest that ERK1/2 signaling pathway is involved in 15-HETE-induced hypoxic pulmonary vasoconstriction.
Animals ; Flavonoids ; pharmacology ; Hydroxyeicosatetraenoic Acids ; antagonists & inhibitors ; pharmacology ; Hypoxia ; physiopathology ; MAP Kinase Signaling System ; physiology ; Male ; Muscle, Smooth, Vascular ; cytology ; Myocytes, Smooth Muscle ; drug effects ; Pulmonary Artery ; cytology ; drug effects ; physiopathology ; Rats ; Rats, Wistar ; Vasoconstriction ; drug effects