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

Pulmonary arterial hypertension (PAH) is a clinical hemodynamic syndrome characterized by elevated pulmonary arterial pressure and pulmonary vascular resistance leading to right heart failure and death. Vascular remodeling is the most prominent histopathological feature of PAH, which is regulated by many factors. Endoplasmic reticulum stress, calcium disorder and mitochondrial dysfunction are involved in the vascular cell proliferation and apoptosis by regulating intracellular calcium homeostasis and cellular metabolism. Epigenetic phenomenon such as DNA damage and abnormal expression of miRNA are also involved in the regulation of abnormal proliferation of vascular cells. Vascular cell phenotype switching including endothelial-mesenchymal transition and smooth muscle cell phenotype switching play an important role in abnormal proliferation of vascular cells. Vascular remodeling is produced by a variety of cells and molecular pathways, and aiming at multiple targets which is expected to find a new breakthrough in the treatment of PAH,and to improve abnormal vascular remodeling, delay or even reverse the progression of PAH.
Cell Proliferation ; Cells, Cultured ; Humans ; Hypertension, Pulmonary ; physiopathology ; MicroRNAs ; genetics ; Myocytes, Smooth Muscle ; pathology ; Pulmonary Artery ; pathology ; Vascular Remodeling ; genetics

Hypertension is a common cardiovascular disease and can induce many complications, such as stroke and coronary heart disease. The purpose of the present study was to investigate the effect of ischemia/hypoxia on mesenteric artery vasomotor function in spontaneously hypertensive rats (SHR). Rat mesenteric arterial rings were cultured in modified ischemia-mimetic solution in a hypoxia incubator for a certain time period. Isometric tension changes of isolated mesenteric arterial rings were recorded continuously by a myograph system. The results obtained were as follows: In SHR group, the maximum contractions to KCl and phenylephrine (PE) were increased, and the maximum relaxation to acetylcholine (ACh) was decreased, compared to those in Wistar-Kyoto (WKY) rats group. Compared with SHR group and WKY with acute ischemia/hypoxia (WKY+H) group, SHR with acute ischemia/hypoxia (SHR+H) increased the maximum contractions induced by KCl and PE and inhibited the maximum relaxations by ACh. In SHR+H and SHR groups, the vasodilation induced by ACh was unaffected by N(G)-nitro-L-arginine methylester (L-NAME), whereas in WKY group, the relaxation to ACh was attenuated by L-NAME. CaCl2-induced contraction in depolarized rings in SHR+H group significantly shifted to the left compared with SHR group. In Ca(2+)-free K-H solution, the maximum contractions induced by PE and caffeine were increased in SHR+H group compared to those in WKY+H group; the PE- and caffeine-induced contractions were also enhanced in SHR group versus WKY group; the maximum contraction induced by PE was significantly increased in SHR+H group versus SHR group. These findings suggest that acute ischemia/hypoxia aggravates mesenteric artery dysfunction in SHR. The mechanism may be related to the decreased NO generation and increased sarcoplasmic reticulum Ca(2+) release.
Animals ; Calcium ; metabolism ; Endothelium, Vascular ; metabolism ; physiopathology ; Hypertension ; physiopathology ; Hypoxia ; physiopathology ; In Vitro Techniques ; Male ; Mesenteric Arteries ; physiopathology ; Muscle, Smooth, Vascular ; physiopathology ; Nitric Oxide ; biosynthesis ; Rats ; Rats, Inbred SHR ; Rats, Inbred WKY ; Vasomotor System ; physiopathology

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 summarize recent advances in human penile anatomy, hemodynamics and their clinical applications.

METHODSUsing dissecting, light, scanning and transmission electron microscopy the fibroskeleton structure, penile venous vasculature, the relationship of the architecture between the skeletal and smooth muscles, and erection hemodynamics were studied on human cadaveric penises and clinical patients over a period of 10 years.

RESULTSThe tunica albuginea of the corpora cavernosa is a bi-layered structure with inner circular and outer longitudinal collagen bundles. Although there is no bone in the human glans, a strong equivalent distal ligament acts as a trunk of the glans penis. A guaranteed method of local anesthesia for penile surgeries and a tunical surgery was developed accordingly. On the venous vasculature it is elucidated that a deep dorsal vein, a couple of cavernosal veins and two pairs of para-arterial veins are located between the Buck's fascia and the tunica albuginea. Furthermore, a hemodynamic study suggests that a fully rigid erection may depend upon the drainage veins as well, rather than just the intracavernosal smooth muscle. It is believed that penile venous surgery deserves another look, and that it may be meaningful if thoroughly and carefully performed. Accordingly, a penile venous surgery was developed.

CONCLUSIONUsing this new insight into penile anatomy and physiology, exact penile curvature correction, refined penile implants and promising penile venous surgery, as well as a venous patch, for treating Peyronie's deformity might be performed under pure local anesthesia on an outpatient basis.

Erectile Dysfunction ; physiopathology ; surgery ; Hemodynamics ; physiology ; Humans ; Male ; Muscle, Skeletal ; anatomy & histology ; Muscle, Smooth, Vascular ; anatomy & histology ; Penile Erection ; physiology ; Penis ; anatomy & histology ; blood supply ; surgery

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

The present study is aimed to investigate the effect of chronic intermittent hypobaric hypoxia (CIHH) on contractile activities in isolated thoracic aorta and pulmonary artery rings and the underlying mechanism in rats. Sprague-Dawley (SD) rats were randomly divided into 4 groups: control group (CON), 14 days CIHH treatment group (CIHH14), 28 days CIHH treatment group (CIHH28) and 42 days CIHH treatment group (CIHH42). CIHH rats were exposed to hypoxia in a hypobaric chamber simulating 5 000 m altitude, 6 h daily for 14, 28 and 42 d, respectively. After artery rings were prepared from pulmonary artery and thoracic aorta, the contractile activity of the artery rings was recorded using organ bath technique. Results are shown as follows. (1) There were no significant differences of noradrenaline (NA)- and KCl-induced contractions in thoracic aorta and pulmonary artery rings among CIHH and CON rats. (2) Angiotensin Ⅱ (ANGⅡ)-induced contraction in thoracic aorta rings, not in pulmonary artery rings, of CIHH rats was decreased compared with that in CON rats. There was no significant difference of ANGⅡ-induced contraction in thoracic aorta rings among CIHH rats. (3) Inhibitory effect of CIHH on ANGⅡ-induced contraction in thoracic aorta rings was endothelium-independent, and was reversed by glibenclamide (Gli), an ATP-sensitive potassium channels (K(ATP)) blocker, and L-NAME, a NO synthase inhibitor, but not by indomethacin (Indo), a cyclooxygenase inhibitor. These results suggest that CIHH attenuates the contraction induced by ANGⅡ in thoracic aorta rings of rat, which is related to the opening of K(ATP) channel and the increased production of NO.
Angiotensin II ; pharmacology ; Animals ; Aorta, Thoracic ; physiopathology ; Hypoxia ; physiopathology ; KATP Channels ; metabolism ; Male ; Muscle Contraction ; physiology ; Muscle, Smooth, Vascular ; physiopathology ; Nitric Oxide ; biosynthesis ; Pulmonary Artery ; physiopathology ; Rats ; Rats, Sprague-Dawley ; Vasoconstriction ; physiology

OBJECTIVETo investigate the electrophysiological changes of voltage-gate potassium channel (Kv) of pulmonary arterial smooth muscle cells of pulmonary arterial hypertension in rats induced by left to right shunt, and to analyze the role of Kv during the progress of pulmonary arterial hypertension.

METHODSForty male SD rats were randomly divided into three groups, group A (control, n = 10), group B (sham operated only group, n = 10), and group C (PAH model group, n = 20). Mean pulmonary artery pressure (mPAP) and right ventricular hypertrophy index (RVHI) of each rat were measured, single pulmonary artery smooth muscle cell (PASMC) was obtained by acute enzyme separation method (collagenase I plus papain) and the conventional whole-cell patch clamp technique was used to record resting membrane potential (Em), potassium ion current of voltage-gated potassium channel, the I-V curve between each 2 groups was compared, and correlation of each parameter was analyzed.

RESULT(1) The mPAP and RVHI of group C were significantly higher than those of group A and group B (P < 0.01, respectively). (2) The Em of group C [(-33.00 ± 4.09) mV] was significantly higher than that of group A [(-48.10 ± 4.54) mV] and group B [(-51.11 ± 3.66) mV], P < 0.01. (3) The peak current at +50 mV of voltage-gated potassium channel: in group C [(64.80 ± 8.40) pA/pF], it was significantly lower than that of group A [(120.85 ± 11.66) pA/pF] and group B [(118.03 ± 10.18) pA/pF] (P < 0.01, respectively). None of the parameters showed any significant difference between group A and group B (P > 0.05 for all comparisons). (4) Compared with group A and group B, the I-V curve of group C significantly downward shifted (P < 0.01, respectively). The difference in I-V curve between group A and group B was not significant, P > 0.05. (5) The correlation of resting membrane potential and mPAP and RVHI had significantly positive correlation (P < 0.001, respectively); but the correlation of membrane current, membrane current density and mPAP, RVHI and resting membrane potential had significantly negative correlation (P < 0.001, respectively).

CONCLUSIONDuring the formation process of left-to-right shunt induced pulmonary arterial hypertension, function of Kv channel was inhibited, suggesting that Kv channel may be the mechanism of pulmonary arterial hypertension induced by left-to-right shunting.

Animals ; Hypertension, Pulmonary ; metabolism ; physiopathology ; Male ; Muscle, Smooth, Vascular ; metabolism ; Patch-Clamp Techniques ; Potassium ; metabolism ; Potassium Channels, Voltage-Gated ; metabolism ; Pulmonary Artery ; metabolism ; physiopathology ; Rats ; Rats, Sprague-Dawley