The aim of the present study was to observe the effects of hypoxia on tensions of aortic rings of pika (Ochotona curzoniae) and Sprague-Dawley (SD) rat. The aortic rings were prepared, and in vitro vascular ring perfusion was used to assay the effects of hypoxia or different drugs on contraction responses of the rings with or without endothelium. The results showed that, there was no difference of the contractions to KCl (80 mmol/L) between the aortic rings of the pikas and SD rats. After pre-contraction with NE (1 μmol/L), the aortic rings with endothelium of the SD rats showed obvious relaxation to ACh (1 μmol/L), whereas the aortic rings of the pikas, no matter with or without endothelium, showed significant and unusual contraction to ACh. The aortic rings of pikas, no matter with or without endothelium, exhibited greater contraction when treated by 1 h of hypoxia, compared with those in SD rats; The similar result was showed under hypoxia in combination with Ca(2+) removal. These results suggest that the contraction response to hypoxia in pika is more sensitive compared to that in SD rat, which is dependent on the release of calcium from intracellular calcium store.
Animals ; Aorta, Thoracic ; physiology ; Arterial Pressure ; Calcium ; physiology ; Hypoxia ; In Vitro Techniques ; Lagomorpha ; Rats ; Rats, Sprague-Dawley

As is well known, the zero stress state of an artery is brought by cutting a ring of the artery radically and then the ring segment springs open into a sector. The zero stress state is a foundation of strain analysis of an artery. There are two methods to measure the dimensions of a blood vessel in the zero stress state. First, it is a way to measure immediately an opening angle. Second, it is a method of assuming that a cut-open, stress-free specimen forms a circular sector and there are two edge angles. In this paper, we proposed a new method to measure the dimensions of an arterial wall in the zero stress state. The new method is to measure immediately the curve length of an arterial wall in zero stress state by computer image process (CIP). We used the curve lengths to define a standard circle for the strain analysis. We compared these three methods on descending thoracic aortas, common carotid arteries, and femoral arteries of white rabbits. Conclusions are: (1) the new method, that is the strain analysis method from the curve length, is the best method among the three methods of strain analysis; (2) the lengths of a ring segment (the length between D/2 and 2D) do not affect the dimensions of the zero stress state.
Animals ; Aorta, Thoracic ; physiology ; Arteries ; physiology ; Carotid Artery, Common ; physiology ; Elasticity ; Femoral Artery ; physiology ; Rabbits ; Stress, Mechanical ; Tensile Strength

Animals ; Aorta, Thoracic ; physiology ; Dopamine ; pharmacology ; Hydrogen-Ion Concentration ; In Vitro Techniques ; Rats ; Vasoconstriction ; drug effects

The mechanical properties of the aorta tissue is not only important for maintaining the cardiovascular health, but also is closely related to the development of cardiovascular diseases. There are obvious differences between the ventral and dorsal tissues of the descending aorta. However, the cause of the difference is still unclear. In this study, a biaxial tensile approach was used to determine the parameters of porcine descending aorta by analyzing the stress-strain curves. The strain energy functions Gasser-Ogden-Holzapfel was adopted to characterize the orthotropic parameters of mechanical properties. Elastic Van Gieson (EVG) and Sirius red stain were used to observe the microarchitecture of elastic and collagen fibers, respectively. Our results showed that the tissue of descending aorta had more orthotropic and higher elastic modulus in the dorsal region compared to the ventral region in the circumferential direction. No significant difference was found in hyperelastic constitutive parameters between the dorsal and ventral regions, but the angle of collagen fiber was smaller than 0.785 rad (45°) in both dorsal and ventral regions. The arrangement of fiber was inclined to be circumferential. EVG and Sirius red stain showed that in outer-middle membrane of the descending aorta, the density of elastic fibrous layer of the ventral region was higher than that of the dorsal region; the amount of collagen fibers in dorsal region was more than that of the ventral region. The results suggested that the difference of mechanical properties between the dorsal and ventral tissues in the descending aorta was related to the microstructure of the outer membrane of the aorta. In the relatively small strain range, the difference in mechanical properties between the ventral and dorsal tissues of the descending aorta can be ignored; when the strain is higher, it needs to be treated differently. The results of this study provide data for the etiology of arterial disease (such as arterial dissection) and the design of artificial blood vessel.
Animals ; Aorta, Thoracic ; physiology ; Biomechanical Phenomena ; Collagen ; Elastic Modulus ; Stress, Mechanical ; Swine

Animals ; Aorta, Thoracic ; physiology ; Endothelium ; blood supply ; Male ; Physical Conditioning, Animal ; physiology ; Rats ; Rats, Sprague-Dawley ; Vasodilation

AIMThrough studying local regulatory mechanisms in pulmonary arteries (PA) and thoracic aortae (TA) under simulated microgravity (SM), to collect some data for the researches of adaptive mechanisms in pulmonary and systemic arteries and for the mechanisms accounting for orthostatic intolerance after SM.

METHODSCardiopulmonary circulatory function during 7-day 6 degrees head down bed rest (HDT) in male young volunteers was measured with a XXH-2000 pulmonary circulation and cardiac function instrument. - 30 degrees C tail suspended (TS) rats were used as the model to simulate the physiological effects of M. The PA and TA changes of vasoreactivity were respectively observed by vitro vessel rings perfusion.

RESULTSThe changes in volume of PA and pulmonary vein during a cardiac cycle and the preload in left cardiac ventricle in men increased significantly in the initial HDT. The super-regulatory phenomena appeared in both pulmonary and systemic circulation, but earlier and more obviously in pulmonary circulation than systemic circulation during 96-144 h. The dilatory reactivity in TS7 PA increased significantly, tended to decrease in TS14. The dilatory reactivity of TA in TS7 had a significant increase, had a slight increase in TS14. The contractile reactivity of PA decreased slightly in TS7 from CON, and were attenuated significantly in TS14. The contractile reactivity of TA in TS14 decreased significantly. The responsiveness to KCl, phenylephrine and sodium nitroprusside in VEC- removed PA had no differences among all groups.

CONCLUSIONThe differences in changes between pulmonary and systemic arteries under SM could be an important sign of depressed local regulatory function, which might be mainly due to dilatory function in VEC and contribute to the occurrence of orthostatic intolerance after SM.

Animals ; Aorta, Thoracic ; physiology ; Humans ; Male ; Pulmonary Artery ; physiology ; Rats ; Rats, Wistar ; Vascular Resistance ; Weightlessness ; Weightlessness Simulation ; Young Adult

By virtue of computational fluid dynamics and the fundamental principles of hemodynamics, this paper gives numerical simulations and analyses of blood flow in the human thoracic aorta. The distributive features of velocity and pressure of the blood flow are obtained with the use of initial parabolic pulsatile blood flow. The numerical results show that, due to the angularity of thoracic aorta and due to the branch arteries, the distributions of velocity and pressure display marked difference, especially for the horizontal velocity, in the thoracic aorta connecting with the second and third branch artery, which indicate the place where thoracic aortic dissection often happens.
Aneurysm, Dissecting ; physiopathology ; Aorta, Thoracic ; physiology ; Aortic Aneurysm, Thoracic ; physiopathology ; Blood Flow Velocity ; physiology ; Blood Viscosity ; Computer Simulation ; Hemodynamics ; Humans ; Models, Cardiovascular ; Pulsatile Flow

Anesthetics, Intravenous ; pharmacology ; Animals ; Aorta, Thoracic ; drug effects ; physiology ; Endothelium, Vascular ; physiology ; Female ; In Vitro Techniques ; Male ; Norepinephrine ; pharmacology ; Potassium Channels ; physiology ; Propofol ; pharmacology ; Rabbits ; Vasodilation ; drug effects

The present paper aims to investigate the relation between characteristic parameters of transesophageal photoelectric pulse wave in descending aorta and ambulatory artery blood pressure. The chests of ten adult experimental dogs were performed to take the photoelectric pulse wave of descending aorta transesophageally. The concurrent femoral artery invasive blood pressure was recorded simultaneously. Stepwise regression analysis method was used to study the correlation efficient between characteristic parameters of descending aorta pulse wave (H, h, h/H, g/H, At, s, H(1 + ts/td), k)and invasive artery blood pressure. The characteristic parameters, k and h/H (ratio: 90% and 80%) was proved that they had good correlation with systolic pressure; and k, H and s (ratio: 90%, 80% and 70%), had good correlation with diastolic pressure; while k and H (ratio: 90% for both) had good correlation with mean pressure. The mean values of multiple correlation coefficients of the selected characteristic parameters of descending aorta pulse wave with systolic pressure, diastolic pressure and mean pressure of femoral artery were 0.871, 0.900 and 0.856, respectively. The characteristic parameters of descending aorta pulse wave had specific correlation with systolic pressure, diastolic pressure and mean pressure.
Animals ; Aorta, Thoracic ; physiology ; Blood Pressure ; physiology ; Blood Pressure Monitoring, Ambulatory ; methods ; Dogs ; Electrophysiologic Techniques, Cardiac ; methods ; Female ; Femoral Artery ; physiology ; Male ; Pulse Wave Analysis ; methods ; Regression Analysis

BACKGROUNDTelocytes (TCs) are a novel type of interstitial cells, which have been recently described in a large variety of cavitary and noncavitary organs. TCs have small cell bodies, and remarkably thin, long, and moniliform prolongations called telopodes (Tps). Until now, TCs have been found in various loose connective tissues surrounding the arterioles, venules, and capillaries, but as a histological cellular component, whether TCs exist in large arteries remains unexplored.

METHODSTCs were identified by transmission electron microscope in the aortic arch of male C57BL/6 mice.

RESULTSTCs in aortic arch had small cell bodies (length: 6.06-13.02 μm; width: 1.05-4.25 μm) with characteristics of specific long (7.74-39.05 μm), thin, and moniliform Tps; TCs distributed in the whole connective tissue layer of tunica adventitia: TCs in the innermost layer of tunica adventitia, located at the juncture between media and adventitia, with their long axes oriented parallel to the outer elastic membrane; and TCs in outer layers of tunica adventitia, were embedded among transverse and longitudinal oriented collagen fibers, forming a highly complex three-dimensional meshwork. Moreover, desmosomes were observed, serving as pathways connecting neighboring Tps. In addition, vesicles shed from the surface of TCs into the extracellular matrix, participating in some biological processes.

CONCLUSIONSTCs in aorta arch are a newly recognized complement distinct from other interstitial cells in large arteries, such as fibroblasts. And further biologically functional correlations need to be elucidated.

Adventitia ; cytology ; Animals ; Aorta ; cytology ; Aorta, Thoracic ; cytology ; Cell Communication ; physiology ; Connective Tissue Cells ; cytology ; ultrastructure ; Male ; Mice ; Mice, Inbred C57BL ; Microscopy, Electron, Transmission