Objective To explore the role of adenosine monophosphate-activated protein kinase (AMPK), a key regulator of cellular energy metabolism, in vascular smooth muscle cell (VSMC) migration in response to physiological cyclic stretch. Methods The Flexcell-5000T mechanical loading system was applied with a physiological cyclic stretch at 10% amplitude and 1.25 Hz frequency to primary rat VSMCs, to simulate mechanical stimulation of VSMCs in vivo. The protein expression of p-AMPK in VSMCs was detected by Western blotting, and VSMC migration was detected by wound healing test. Results Compared with the static group, physiological cyclic stretch loading for 24 h significantly decreased the area of wound healing, indicating that physiological cyclic stretch inhibited VSMC migration. The protein expression of p-AMPK in VSMCs was increased significantly after physiological cyclic stretch loading for 3 h, and was decreased significantly after 24 h. Under physiological cyclic stretch loading conditions, incubating AMPK inhibitor could significantly reduce the protein expression of p-AMPK after 3 h, and promote VSMC migration after 24 h; incubating AMPK activator AICAR under static conditions significantly increased the protein expression of p-AMPK after 3 h, and weakened VSMC migration after 24 h. Conclusions Physiological cyclic stretch inhibits VSMC migration by increasing the protein expression of p-AMPK, indicating that VSMC migration regulated by physiological cyclic stretch is of great significance for maintaining vascular homeostasis.

This study sought to probe into the mechanism of spontaneous contraction of portal vein. The morphological and electrophysiological characteristics of the freshly isolated interstitial cells (ICs) of rabbit portal vein were investigated by using immunohistochemical and conventional whole-cell patch clamp techniques. The isolated interstitial cells exhibited stellate-shaped or spindle-shaped bodies with a variable number of thin processes projecting from cell bodies, and these cells were noted to be c-Kit immunopositive. Under conventional whole-cell patch clamp configuration, the membrane potential was held at -60 mV, the spontaneous rhythmic inward currents were recorded in ICs, and the frequencies of which were similar to those of spontaneous contraction of portal vein. The inward currents were insensitive to nicardipine (an L-type calcium channel blocker) but could be abolished by gadolinium (a non-selective cation channel blocker). The results suggested that the spontaneous rhythmic inward currents recorded in freshly isolated ICs may be pacemaker currents which elicit the spontaneous contraction of portal vein.
Action Potentials ; Animals ; Electrophysiology ; Female ; Interstitial Cells of Cajal ; physiology ; Male ; Muscle, Smooth, Vascular ; physiology ; Periodicity ; Portal Vein ; cytology ; physiology ; Rabbits ; Transient Receptor Potential Channels ; metabolism

Objective To evaluate the role of angiotensin Ⅱ(AngⅡ) signal passway on the expression of Rho GDP dissociation inhibitor alpha (RhoGDIα) in hypertensive rats. Methods Protein and mRNA expressions of RhoGDIα in aortae of 4, 12 and 18 week-old spontaneously hypertensive rats (SHR, n = 4) and Wistar Kyoto rats (WKY, n= 4) were examined by Western blotting and real-time PCR. Aortas from SHR and WKY were analyzed using immonuchemical staining to locate the RhoGDIα in the aorta. The RhoGDIα expression in aorta of hypertensive rat model of aorta coarctation (ACR, n = 6) was also analyzed using Western blotting. Furthermore, The effect of mechanical strain at 10 % elongation on expression of RhoGDIα in vascular smoothmuscle cells (VSMCs) in the presence or absence of L-158809, an antagonist for AngⅡ type 1 receptor, was also evaluated by Western blotting. Results No significant difference of RhoGDIα expression was found between SHR and WKY at 4-week-old and 12-week-old. However, in 18-week-old group, RhoGDIα was significantly highly expressed in SHR than that of WKY at both mRNA and protein levels. RhoGDIα was located in the media of the aorta. Expression of RhoGDIα protein was upregulated in aortas of ACR at 2 and 4 weeks as compared with the controls. The expression of RhoGDIα in VSMCs was inhibited by mechanicalstrain at 10 % elongation, and further decreased by treatment of L-158809. Conclusion RhoGDIα is upregulated in aortae of the hypertensive rats. AngⅡ signal passway may be involved in the process of regulating expression of RhoGDIα.

To investigate the effect of different frequencies of cyclic tensile strain on extracellular matrix (ECM) of vascular smooth muscle cells (VSMCs) and to research the relationship between tensile strain and vascular remodeling, the aortic vascular smooth muscle cells of rats grown on dishes coated with collagen I were subjected to 10% elongation and various frequencies of mechanical strain using the Flexercell 4000 Strain Unit. The expression of extracellular matrix including fibronectin, collagen I and collagen III was detected by Real-time RT-PCR, and p38 activity by western blot. The result showed that the expression of extracellular matrix was induced by mechanical strain in a nonlinear frequency-dependent manner, which was mediated by p38 pathway. These results demonstrate that the variety of frequencies of cyclic tensile strain could modulate the expression of ECM. It may have important influence on vascular remodeling.
Animals ; Aorta ; cytology ; Cells, Cultured ; Collagen Type I ; biosynthesis ; Collagen Type III ; biosynthesis ; Extracellular Matrix ; metabolism ; Fibronectins ; biosynthesis ; Male ; Mechanotransduction, Cellular ; physiology ; Muscle, Smooth, Vascular ; cytology ; physiology ; Rats ; Rats, Sprague-Dawley ; Stress, Mechanical

Portal hypertension is a common physiopathological change in liver cirrhosis. In this study, rabbits were used and the model of pre-hepatic portal hypertension (PHT) was induced by partial ligation of portal vein in two steps. We measured the diameters of portal vein and small mesenteric vein at different time-points. Then we detected the stress forces induced by blood flow in varicose veins and in portal vein; such forces included hydrostatic pressure, shear stress and circumferential stress. With the increase of the diameter of varicose small mesenteric vein, the hydrostatic pressure and circumferential stress gradually elevated and shear stress descended markedly in both the portal vein and the small mesenteric vein of PHT rabbits, between which there was a positive linear correlation. The findings in our study indicate that the complications of PHT are partially attributable to the environment of lower shear stress and higher circumferential stress in which the blood vessels of portal venous system live.
Animals ; Hemodynamics ; Hypertension, Portal ; etiology ; pathology ; physiopathology ; Mesenteric Veins ; pathology ; physiopathology ; Portal Vein ; pathology ; physiopathology ; Rabbits ; Stress, Mechanical ; Vascular Resistance ; physiology ; Venous Pressure

In order to investigate the mechanism of mechanical stress-mediated arterial remodeling, we studied the pressure-induced expression of immediate-early response gene product c-Jun in common carotid arteries in rats. The common carotid arteries were perfused with both high pressure (160 mmHg) and normal pressure (80 mmHg) for 0.5, 1, 3 and 6 hours. Expression of immediate-early response gene product c-Jun in the arteries was examined by immunohistochemistry and computer image processing. c-Jun was weakly expressed at 1 h, then increased at 3 h and 6 h after exposure of the arteries to normal pressure. Positive immunohistochemical product of c-Jun appeared in the arteries at 0.5 h after the onset of high pressure, then it increased markedly till 6 h. There was significant difference between the two groups. These results indicate that expression of c-Jun of the arteries can be induced by pressure, which may play an important role in mechanical stress-mediated arterial remodeling.
Animals ; Biomechanical Phenomena ; Carotid Artery, Common ; cytology ; metabolism ; physiology ; Genes, Immediate-Early ; Male ; Muscle, Smooth, Vascular ; cytology ; metabolism ; Pressure ; Proto-Oncogene Proteins c-jun ; biosynthesis ; genetics ; Rats ; Rats, Sprague-Dawley ; Stress, Mechanical

To explore the biological effects of shear stress on intact artery and the change of growth factor during stress-induced vascular remodeling, we established an artery organ-cultured system under stress in vitro, and the common carotid arteries of pigs were cultured under shear stress of 20, 5 and 0 dyn/cm2. PDGF-A synthesis of vascular smooth muscle cells (VSMCs) cultured for 1, 4 and 7 days were studied by immunohistochemical and computer image processing methods, and PDGF-B secretion of endothelial cells (ECs) cultured within 12 h were studied by ELISA. Results showed that PDGF-B increased obviously under shear stress of 5 dyn/cm2, and reached the highest point at about 3 h; PDGF-A synthesis also obviously increased under low shear stress in 7 days. Increasing of PDGF synthesis promotes phenotype switch and proliferation of VSMC. It may have important influence on artery remodeling under low shear stress.
Animals ; Carotid Artery, Common ; chemistry ; metabolism ; Cells, Cultured ; Endothelium, Vascular ; cytology ; metabolism ; Muscle, Smooth, Vascular ; cytology ; metabolism ; Platelet-Derived Growth Factor ; biosynthesis ; Shear Strength ; Stress, Mechanical ; Swine

To explore primarily the reconstruction of biological tissue engineered blood vessel in vitro, the decellularised scaffolds were obtained from swine common carotid arteries by enzyme digestion, and vascular smooth muscle cells (VSMCs) were isolated from canine thoracic aorta and subcultured and purified. The VSMCs were seeded into the inner surface of scaffolds and they were cocultured in vitro for 4 weeks. Histological staining and transmission electron microscopy were used to observe the growth of canine VSMCs on swine decellularized arterial scaffolds. The results showed the seeded VSMCs grew well on the decellularized scaffold throughout the duration of 4 weeks, which suggests that the method in this article is practicable for reconstructing complete biological tissue engineering blood vessel.
Animals ; Arteries ; Blood Vessel Prosthesis ; Cells, Cultured ; Coculture Techniques ; Dogs ; Microscopy, Electron, Transmission ; Muscle, Smooth, Vascular ; cytology ; Myocytes, Smooth Muscle ; cytology ; Swine ; Tissue Engineering ; Tissue Scaffolds