Animals ; Carotid Arteries ; physiology ; Cerebral Angiography ; Cerebral Arteries ; physiology ; Cerebrovascular Circulation ; Humans ; Rats ; Vertebral Artery ; physiology

In physiology-related books, there are many relationship curves about blood flow rate in arteries and blood pressure changes with time, but there are not much explanation about such relationship. This is the very the question that the present article tries to answer. We clarified the relations between blood flow rate and blood pressure gradient using the experimental curves as the basis, using Poiseuille Law and relative knowledge of phisics and mathematics, and using analysis and reasoning. Based on the study, it can be concluded that in every course of cardiac cycle, the blood flow rate of any section in artery blood vessel is roughly synchronized with changing rate of space and time of the blood pressure, but blood flow rate is not synchronized with blood pressure.
Arterial Pressure ; physiology ; Arteries ; physiology ; Blood Flow Velocity ; physiology ; Humans ; Time

OBJECTIVETo probe into the reflection of "artery" phenomenon in human channels.

METHODSFind out the discussion about "artery" from ancient medical books and compare with Chinese ancient philosophy thoughts.

RESULTSIn TCM, "artery" has been used as reference in differentiating channels. The circulation system of channels is possibly established on the expectation of "to and fro circulation" in the Chinese philosophy, and the power of channels originates from the qi stored between the kidney, and the pricking blood therapy was used for treatment of many kinds of diseases in ancient times.

CONCLUSIONStudy on channels should pay attention to this link of "artery".

Arteries ; anatomy & histology ; physiology ; Humans ; Medicine, Chinese Traditional ; Meridians

OBJECTIVEA variety of inner ear disease is related to microcirculation disturbance of inner ear, but smooth muscle cells (SMC) and endothelial cells (EC) of the spiral modiolar artery (SMA), which is the main blood supply to the inner ear, physiological feature is not very clear.

METHODSIn this study, two-intracellular microelectrode recording technique and cell staining techniques to study the SMC and EC resting membrane potential characteristics and communication links between cells of SMA.

RESULTSStudy found that SMC and EC have high and low resting membrane potential state, two state of the resting membrane potential of cells to ACh and high K+ response is completely different. The different types of cells, EC-EC, SMC-SMC and SMC-EC, can simultaneously record by two-microelectrode, two cell resting membrane potential can also be a double-high RP, double-low RP and one high- and one low- RP. Experiment recorded in one high- and one low- RP are the SMC-EC types, and ECs initial membrane potential are high potential, SMCs membrane potential are low initial potential. The double-high and double-low RP can be SMC-SMC or EC-EC or SMC-EC types.

CONCLUSIONThe results show that SMC and EC in the 0.3 - 0.5 mm range, similar type of cells have very good communication, can function together to maintain good and consistent, heterogeneous cell performance is more different.

Animals ; Arteries ; cytology ; Cochlea ; blood supply ; physiology ; Endothelial Cells ; physiology ; Guinea Pigs ; Membrane Potentials ; physiology ; Myocytes, Smooth Muscle ; physiology

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

OBJECTIVEReduced arterial elasticity is a hallmark of aging in healthy humans independently of diseases and endothelial-cell injury and dysfunction may be responsible for this fall in arterial elasticity. We hypothesized that circulating endothelial progenitor cells (EPCs) are involved in endothelial repair and that lack of EPCs contributes to impaired arterial elasticity.

METHODSA total of 56 healthy male volunteers were divided into young (n = 26) and elderly (n = 30) groups. Large and small artery elasticity indices were non-invasively assessed by using pulse wave analysis. Flow cytometer was used to count the number of circulating CD34(+) mononuclear cells (MNCs), which were isolated from peripheral blood by Ficoll density gradient centrifugation, and then the cells were plated on fibronectin-coated culture dishes. EPCs were characterized as adherent cells double positive staining for DiI-acLDL uptake and lectin binding with using fluorescent microscope.

RESULTSC(1) (large artery elasticity index) and C(2) (small artery elasticity index) were significantly reduced in the elderly group compared with those in the young group (11.73 +/- 1.45 vs 16.89 +/- 1.69 ml/mm Hg x 10, P < 0.001; 8.40 +/- 1.45 vs 10.58 +/- 1.18 ml/mm Hg x 100, P < 0.001 respectively). In parallel, the number of circulating EPCs was significantly reduced in the elderly group compared with the young group (0.13 +/- 0.02 vs 0.17 +/- 0.04%, P < 0.05). The number of circulating EPCs correlated with C(1) large and C(2) small artery elasticity indices (r = 0.47, P < 0.01; r = 0.4, P < 0.01). Fluorescent microscope was used to identify EPCs, which were double positive staining for DiI-acLDL uptake and lectin binding.

CONCLUSIONThe present findings suggested that the fall in circulating EPCs with subsequently impaired endothelial-cell repair and function might contribute to reduced arterial elasticity in humans with aging. The decrease in circulating EPCs could serve as a surrogate biologic measure of vascular function and human age.

Adult ; Aged ; Aging ; physiology ; Arteries ; physiology ; Elasticity ; Endothelial Cells ; cytology ; physiology ; Humans ; Male ; Middle Aged ; Stem Cells ; cytology ; physiology

To explore the changes of wall shear stress(WSS) effect on arterial endothelial cell(EC) apoptosis after reducing arterial blood flow. The reducing flow model was established in 60 rabbits. Endothelial stretched preparations were made at 8 different time intervals from 0 to 30 days. The apoptosis rate of arterial endothelial cells (AEC) was measured with TdT-mediated dUTP-biotin nick end labeling(TUNEL) method. The results showed that the apoptosis rate of AEC was significantly higher from 1 day to 7 days after decreasing WSS than that of control, which peaked on day 3. While with progressively increasing in WSS, the apoptosis rate restored to the level of control from 14 days to 30 days. These suggest that the apoptosis state of AEC might be markedly influenced by the changes of WSS. The persist decreasing of WSS may be the important factor which induces the cell apoptosis.
Animals ; Apoptosis ; Arteries ; cytology ; physiology ; Endothelium, Vascular ; cytology ; physiology ; Male ; Rabbits ; Regional Blood Flow ; Shear Strength

BACKGROUNDThe offspring of women with gestational diabetes mellitus (GDM) are prone to macrosomia. However, birth weight is difficult to be correctly estimated by ultrasound because of fetal asymmetric growth characteristics. This study aimed to investigate the correlations between fetal hemodynamics, fetal growth indices in late pregnancy, and birth weight in GDM.

METHODSA total of 147 women with GDM and 124 normal controls (NC) were enrolled in this study. Fetal hemodynamic indices, including the systolic/diastolic ratio (S/D), resistance index (RI), pulsatility index (PI) of umbilical artery (UA), middle cerebral artery (MCA), and renal artery (RA), were collected. Fetal growth indices, including biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length, were also measured by ultrasound. Birth weight, newborn gender, and maternal clinical data were collected.

RESULTSThe independent samples t-test showed that BPD, HC, and AC were larger in GDM than in NC (P < 0.05). Fetal hemodynamic indices of the UA and MCA were lower (P < 0.05), but those of the RA were higher (P < 0.001) in GDM than in NC. Birth weight was higher in GDM than in NC (P < 0.001). Pearson's correlation analysis showed that hemodynamic indices of the UA were negatively correlated with birth weight, BPD, HC, and AC in both groups (P < 0.05). MCA (S/D, PI, and RI) was negatively correlated with birth weight, HC, and AC in GDM (r = -0.164, -0.206, -0.200, -0.226, -0.189, -0.179, -0.196, -0.177, and - 0.172, respectively, P< 0.05), but there were no correlations in NC (P > 0.05). RA (S/D, PI, and RI) was positively correlated with birth weight in GDM (r = 0.168, 0.207, and 0.184, respectively, P< 0.05), but there were no correlations in NC (P > 0.05).

CONCLUSIONFetal hemodynamic indices in late pregnancy might be helpful for estimating newborn birth weight in women with GDM.

Adult ; Birth Weight ; physiology ; Cerebral Arteries ; physiology ; Diabetes, Gestational ; physiopathology ; Female ; Fetal Development ; physiology ; Hemodynamics ; physiology ; Humans ; Infant, Newborn ; Male ; Pregnancy ; Pregnancy Outcome ; Renal Artery ; physiology ; Ultrasonography, Prenatal ; Umbilical Arteries ; physiology

The aim of the present study was to further elucidate the mechanisms of vascular adaptation to microgravity and its gravity-based countermeasure by a biomechanical approach. Active (the dissected vessel segment was superfused with PPS) and passive (while it was superfused with Ca(2+)-free PPS) biomechanical properties of mesenteric third-order small arteries and middle cerebral arteries isolated from 3-day simulated microgravity (SUS), countermeasure (STD, daily 1 h of -G(x) gravitation), and control (CON) groups of rats were studied. The following mechanical parameters were calculated: the overall stiffness parameter of passive vessels (beta), circumferential stress (sigma(theta))-strain (epsilon(theta)) relationship, and pressure-dependent incremental elastic modulus (E(inc,p)) of both active and passive vessels, and vascular smooth muscle (VSM) activity-dependent incremental modulus (E(inc,a)). Results from the analysis of active biomechanical properties revealed the contribution of vascular smooth muscle (VSM) tone during the early adaptation to microgravity: (1) For mesenteric small arteries, active circumferential sigma(theta) -epsilon(theta) curve of SUS group was comparable with that of the passive vessels, indicating that the function of VSM to restore the normal stress distribution is compromised; however, this mal-adaptation was fully prevented by the countermeasure of daily 1 h of -G(x) gravitation; (2) For the middle cerebral arteries, active circumferential sigma(theta) -epsilon(theta) relation of SUS group was shifted to the left side of the passive curve and epsilon(theta) was kept at a nearly constant level with the corresponding sigma(theta) being at its normal range; furthermore, the enhanced myogenic tone responsiveness was not prevented by daily short-duration -G(x). Analysis of the passive biomechanical properties has suggested remodeling changes in matrix components of different types of vessels, which might be significant if the exposure duration was further prolonged. In brief, studies of vascular biomechanics are of particular importance in elucidating the mechanisms underlying vascular adaptation to microgravity and its gravity-based countermeasure.
Animals ; Biomechanical Phenomena ; Mesenteric Arteries ; physiology ; Middle Cerebral Artery ; physiology ; Muscle, Smooth, Vascular ; physiology ; Pressure ; Rats ; Weightlessness Simulation

The aim of the present study was to investigate the effect of removal of the adventitia on vascular remodeling and vasoconstriction of the carotid artery in New Zealand rabbit. Adventitia of carotid artery was removed mechanically. The histology, morphology and reactivity of the carotid artery was observed by immunohistochemistry and measurement of carotid ring tension immediately, 1 week and 2 weeks after removal of the adventitia. No damage of intima and media was observed after removing the adventitia. Removal of the adventitia caused a remarkable proliferation of the vascular media and formed the neointima. Compared with the control ring, norepinephrine (NE)-induced vasocontraction in adventitia-denuded carotid artery was significantly reduced immediately and 1 week after the operation (P<0.05). Adventitia removal promoted the neointima formation and decreased vasoconstriction of the carotid artery, indicating that the adventitia is involved in the regulation of vascular remodeling and vasoconstriction.
Animals ; Carotid Arteries ; pathology ; physiology ; surgery ; Connective Tissue ; physiology ; surgery ; Muscle, Smooth, Vascular ; pathology ; Rabbits ; Tunica Intima ; pathology ; Vasoconstriction ; physiology