Effects of NO-Donors on Thrombus Formation and Microcirculation in Cerebral Vessels of the Rat

1996 ◽  
Vol 76 (01) ◽  
pp. 111-117 ◽  
Author(s):  
Yasuto Sasaki ◽  
Junji Seki ◽  
John C Giddings ◽  
Junichiro Yamamoto
Keyword(s):  
Blood Flow ◽  
Thrombus Formation ◽  
Dependent Manner ◽  
Red Cell ◽  
Cell Velocity ◽  
Red Cell Velocity ◽  
The Mean ◽  
Wall Shear ◽  
Dose Dependent

SummarySodium nitroprusside (SNP) and 3-morpholinosydnonimine (SIN-1), are known to liberate nitric oxide (NO). In this study the effects of SNP and SIN-1 on thrombus formation in rat cerebral arterioles and venules in vivo were assessed using a helium-neon (He-Ne) laser. SNP infused at doses from 10 Μg/kg/h significantly inhibited thrombus formation in a dose dependent manner. This inhibition of thrombus formation was suppressed by methylene blue. SIN-1 at a dose of 100 Μg/kg/h also demonstrated a significant antithrombotic effect. Moreover, treatment with SNP increased vessel diameter in a dose dependent manner and enhanced the mean red cell velocity measured with a fiber-optic laser-Doppler anemometer microscope (FLDAM). Blood flow, calculated from the mean red cell velocity and vessel diameters was increased significantly during infusion. In contrast, mean wall shear rates in the arterioles and venules were not changed by SNP infusion. The results indicated that SNP and SIN-1 possessed potent antithrombotic activities, whilst SNP increased cerebral blood flow without changing wall shear rate. The findings suggest that the NO released by SNP and SIN-1 may be beneficial for the treatment and protection of cerebral infarction

scholarly journals Antithrombotic Effect of Crotalin, a Platelet Membrane Glycoprotein Ib Antagonist From Venom of Crotalus atrox

Blood ◽  
1998 ◽  
Vol 91 (5) ◽  
pp. 1582-1589
Author(s):  
Mei-Chi Chang ◽  
Hui-Kuan Lin ◽  
Hui-Chin Peng ◽  
Tur-Fu Huang
Keyword(s):  
Platelet Aggregation ◽  
Latent Period ◽  
Bleeding Time ◽  
Thrombus Formation ◽  
Platelet Membrane ◽  
Dependent Manner ◽  
Glycoprotein Ib ◽  
Platelet Surface ◽  
Dose Dependent

A potent platelet glycoprotein Ib (GPIb) antagonist, crotalin, with a molecular weight of 30 kD was purified from the snake venom ofCrotalus atrox. Crotalin specifically and dose dependently inhibited aggregation of human washed platelets induced by ristocetin with IC50 of 2.4 μg/mL (83 nmol/L). It was also active in inhibiting ristocetin-induced platelet aggregation of platelet-rich plasma (IC50, 6.3 μg/mL). 125I-crotalin bound to human platelets in a saturable and dose-dependent manner with a kd value of 3.2 ± 0.1 × 10−7 mol/L, and its binding site was estimated to be 58,632 ± 3,152 per platelet. Its binding was specifically inhibited by a monoclonal antibody, AP1 raised against platelet GPIb. Crotalin significantly prolonged the latent period in triggering platelet aggregation caused by low concentration of thrombin (0.03 U/mL), and inhibited thromboxane B2formation of platelets stimulated either by ristocetin plus von Willebrand factor (vWF), or by thrombin (0.03 U/mL). When crotalin was intravenously (IV) administered to mice at 100 to 300 μg/kg, a dose-dependent prolongation on tail bleeding time was observed. The duration of crotalin in prolonging tail bleeding time lasted for 4 hours as crotalin was given at 300 μg/kg. In addition, its in vivo antithrombotic activity was evidenced by prolonging the latent period in inducing platelet-rich thrombus formation by irradiating the mesenteric venules of the fluorescein sodium-treated mice. When administered IV at 100 to 300 μg/kg, crotalin dose dependently prolonged the time lapse in inducing platelet-rich thrombus formation. In conclusion, crotalin specifically inhibited vWF-induced platelet agglutination in the presence of ristocetin because crotalin selectively bound to platelet surface receptor-glycoprotein Ib, resulting in the blockade of the interaction of vWF with platelet membrane GPIb. In addition, crotalin is a potent antithrombotic agent because it pronouncedly blocked platelet plug formation in vivo.

scholarly journals Antithrombotic Effect of Crotalin, a Platelet Membrane Glycoprotein Ib Antagonist From Venom of Crotalus atrox

Blood ◽  
1998 ◽  
Vol 91 (5) ◽  
pp. 1582-1589 ◽  
Author(s):  
Mei-Chi Chang ◽  
Hui-Kuan Lin ◽  
Hui-Chin Peng ◽  
Tur-Fu Huang
Keyword(s):  
Platelet Aggregation ◽  
Latent Period ◽  
Bleeding Time ◽  
Thrombus Formation ◽  
Platelet Membrane ◽  
Dependent Manner ◽  
Glycoprotein Ib ◽  
Platelet Surface ◽  
Dose Dependent

AbstractA potent platelet glycoprotein Ib (GPIb) antagonist, crotalin, with a molecular weight of 30 kD was purified from the snake venom ofCrotalus atrox. Crotalin specifically and dose dependently inhibited aggregation of human washed platelets induced by ristocetin with IC50 of 2.4 μg/mL (83 nmol/L). It was also active in inhibiting ristocetin-induced platelet aggregation of platelet-rich plasma (IC50, 6.3 μg/mL). 125I-crotalin bound to human platelets in a saturable and dose-dependent manner with a kd value of 3.2 ± 0.1 × 10−7 mol/L, and its binding site was estimated to be 58,632 ± 3,152 per platelet. Its binding was specifically inhibited by a monoclonal antibody, AP1 raised against platelet GPIb. Crotalin significantly prolonged the latent period in triggering platelet aggregation caused by low concentration of thrombin (0.03 U/mL), and inhibited thromboxane B2formation of platelets stimulated either by ristocetin plus von Willebrand factor (vWF), or by thrombin (0.03 U/mL). When crotalin was intravenously (IV) administered to mice at 100 to 300 μg/kg, a dose-dependent prolongation on tail bleeding time was observed. The duration of crotalin in prolonging tail bleeding time lasted for 4 hours as crotalin was given at 300 μg/kg. In addition, its in vivo antithrombotic activity was evidenced by prolonging the latent period in inducing platelet-rich thrombus formation by irradiating the mesenteric venules of the fluorescein sodium-treated mice. When administered IV at 100 to 300 μg/kg, crotalin dose dependently prolonged the time lapse in inducing platelet-rich thrombus formation. In conclusion, crotalin specifically inhibited vWF-induced platelet agglutination in the presence of ristocetin because crotalin selectively bound to platelet surface receptor-glycoprotein Ib, resulting in the blockade of the interaction of vWF with platelet membrane GPIb. In addition, crotalin is a potent antithrombotic agent because it pronouncedly blocked platelet plug formation in vivo.

scholarly journals Hirudin interruption of heparin-resistant arterial thrombus formation in baboons

Blood ◽  
1991 ◽  
Vol 77 (5) ◽  
pp. 1006-1012 ◽  
Author(s):  
AB Kelly ◽  
UM Marzec ◽  
W Krupski ◽  
A Bass ◽  
Y Cadroy ◽  
...  
Keyword(s):  
Bleeding Time ◽  
Thrombus Formation ◽  
Dependent Manner ◽  
Fibrin Deposition ◽  
Recombinant Hirudin ◽  
Arterial Thrombus ◽  
Dependent Inhibition ◽  
Antithrombotic Effects ◽  
Dose Dependent

Abstract To determine the role of thrombin in high blood flow, platelet- dependent thrombotic and hemostatic processes we measured the relative antithrombotic and antihemostatic effects in baboons of hirudin, a highly potent and specific antithrombin, and compared the effects of heparin, an antithrombin III-dependent inhibitor of thrombin. Thrombus formation was determined in vivo using three relevant models (homologous endarterectomized aorta, collagen-coated tubing, and Dacron vascular graft) by measuring: (1) platelet deposition, using gamma camera imaging of 111In-platelets; (2) fibrin deposition, as assessed by the incorporation of circulating 125I-fibrinogen; and (3) occlusion. The continuous intravenous infusion of 1, 5, and 20 nmol/kg per minute of recombinant hirudin (desulfatohirudin) maintained constant plasma levels of 0.16 +/- 0.03, 0.79 +/- 0.44, and 3.3 +/- 0.77 mumol/mL, respectively. Hirudin interrupted platelet and fibrin deposition in a dose-dependent manner that was profound at the highest dose for all three thrombogenic surfaces and significant at the lowest dose for thrombus formation on endarterectomized aorta. Thrombotic occlusion was prevented by all doses studied. In contrast, heparin did not inhibit either platelet or fibrin deposition when administered at a dose that maximally prolonged clotting times (100 U/kg) (P greater than .1), and only intermediate effects were produced at 10-fold that dose (1,000 U/kg). Moreover, heparin did not prevent occlusion of the test segments. Hirudin inhibited platelet hemostatic function in concert with its antithrombotic effects (bleeding times were prolonged by the intermediate and higher doses). By comparison, intravenous heparin failed to affect the bleeding time at the 100 U/kg dose (P greater than .5), and only minimally prolonged the bleeding time at the 1,000 U/kg dose (P less than .05). We conclude that platelet-dependent thrombotic and hemostatic processes are thrombin-mediated and that the biologic antithrombin hirudin produces a potent, dose-dependent inhibition of arterial thrombus formation that greatly exceeds the minimal antithrombotic effects produced by heparin.

scholarly journals Selectin-mediated rolling of neutrophils on immobilized platelets

Blood ◽  
1993 ◽  
Vol 82 (4) ◽  
pp. 1165-1174 ◽  
Author(s):  
SM Buttrum ◽  
R Hatton ◽  
GB Nash
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Shape Change ◽  
Vascular Occlusion ◽  
Rolling Velocity ◽  
Cell Shape Change ◽  
Cell Velocity ◽  
The Mean ◽  
Wall Shear

Abstract Interaction between neutrophils and platelets at the site of vascular damage or in ischaemic tissue may promote thrombosis and/or vascular occlusion. To study this interaction, we have developed a novel technique that allows visualization of adhesion of flowing neutrophils to immobilized, activated platelets. The total number of adherent neutrophils decreased with increasing wall shear stress in the range 0.05 to 0.4 Pa. Although a proportion of the adherent neutrophils were stationary, most were rolling with a velocity greater than 0.4 micron/s. The percentage of rolling cells increased with increasing wall shear stress, but the mean rolling cell velocity was nearly independent of shear stress. Adhesion of neutrophils was nearly abolished by treatment of the platelets with antibody to P-selectin, or by treatment of neutrophils with either neuraminidase, dextran sulfate, or EDTA. Studies with a series of antibodies to L-selectin (TQ-1, Dreg- 56, LAM1–3, and LAM1–10) suggested that this molecule was one neutrophil ligand for rolling adhesion. Thus, sialylated carbohydrate on neutrophils appears essential for P-selectin-mediated adhesion, and a proportion of this ligand may be presented by L-selectin. Treatment of the neutrophils with N-formyl-methionyl-leucyl-phenylalanine decreased the number of rolling cells, and increased the rolling velocity, possibly due to shedding of neutrophil ligand(s) and/or cell shape change. In vivo, immobilized platelets could play an important role in promoting attachment of neutrophils to vessel walls, eg, by slowing neutrophils so that integrin-mediated immobilization could occur.

ET-1 induced alterations of hepatic microcirculation: sinusoidal and extrasinusoidal sites of action

1994 ◽  
Vol 267 (1) ◽  
pp. G143-G149 ◽  
Author(s):  
M. Bauer ◽  
J. X. Zhang ◽  
I. Bauer ◽  
M. G. Clemens
Keyword(s):  
Recovery Period ◽  
Epifluorescence Microscopy ◽  
Microvascular Blood Flow ◽  
Red Cell ◽  
Hepatic Microcirculation ◽  
Cell Velocity ◽  
Red Cell Velocity ◽  
Sites Of Action ◽  
Systemic Application

Using epifluorescence microscopy, we investigated the dynamic changes in hepatic sinusoidal hemodynamics in vivo during continuous infusion of endothelin-1 (ET-1) in pentobarbital-anesthetized rats. ET-1 was infused for 20 min at rates of 2 or 10 pmol/min either systemically or into the portal vein, followed by a 90-min recovery period. In contrast to systemic application of ET-1 that did not cause a consistent hepatic microvascular effect, we observed two different patterns of microcirculatory alterations during portal application. Infusion of 2 pmol/min elicited a rapid, reversible decrease in sinusoidal diameter that was paralleled by a slight increase in red cell velocity, resulting in conservation of volumetric flow and sinusoid density. Infusion of 10 pmol/min resulted in a biphasic narrowing followed by transient increase in sinusoidal diameter and a profound and lasting decrease in red cell velocity, leading to an almost complete cessation of hepatic microvascular blood flow. These results indicate that ET-1 is a potent constrictor in the liver microcirculation in vivo and acts at both extrasinusoidal and sinusoidal sites, although the sinusoidal sites appear to be more sensitive to lower concentrations.

Red cell perfusion in skeletal muscle at rest and after mild and severe contractions

1987 ◽  
Vol 252 (3) ◽  
pp. H485-H493 ◽  
Author(s):  
K. Tyml
Keyword(s):  
Sartorius Muscle ◽  
Red Cell ◽  
Capillary Length ◽  
Mean Values ◽  
Pooled Data ◽  
Cell Velocity ◽  
Red Cell Velocity ◽  
The Mean ◽  
O2 Supply ◽  
First Time

The aim of this study was to evaluate the distribution of red cell perfusion in sartorius muscle of anesthetized frogs by analyzing simultaneously red cell velocity (VRBC), number of cells per unit capillary length (NRBC), and density of perfused capillaries (CD) in a 2.07 X 2.71-mm region of the muscle visualized microscopically at very low magnification. In the 16 muscles studied, a severe 1-min electrical stimulation induced statistically significant increases in the mean values, VRBC, NRBC, and CD, as well as significant decreases in heterogeneities (SD/mean) of these three parameters when going from rest to postcontraction hyperemia. A mild 3-s stimulation caused significant increases only in VRBC and NRBC. Red cell perfusion, computed as a product of the three parameters divided by the mean capillary length, increased significantly from 87.4 +/- 81.9 to 417.9 +/- 118.2 (SD) and from 96.9 +/- 75.7 to 192.5 +/- 190.2 (SD) cells X s-1 X mm-3, respectively. In both stimulations, the postcontraction increase of red cell supply to the muscle, expressed in cells per second per cubic millimeter, was larger than any individual increase in the three parameters. Based on pooled data from all muscles, both NRBC and CD were determined to be dependent on VRBC. The present study supports the view that VRBC, NRBC, CD, and heterogeneity of red cell distribution depend on vascular tone and demonstrates for the first time that these four dependencies can operate both concurrently and synergistically to increase O2 supply to muscle after contraction.

scholarly journals Shear rate gradients promote a bi-phasic thrombus formation on weak adhesive proteins, such as fibrinogen in a VWF-dependent manner

Haematologica ◽  
2019 ◽  
Vol 105 (10) ◽  
pp. 2471-2483 ◽  
Author(s):  
Nicolas Receveur ◽  
Dmitry Nechipurenko ◽  
Yannick Knapp ◽  
Aleksandra Yakusheva ◽  
Eric Maurer ◽  
...  
Keyword(s):  
Blood Flow ◽  
Shear Rate ◽  
Steady Flow ◽  
Thrombus Formation ◽  
Fiber Formation ◽  
Second Phase ◽  
Dependent Manner ◽  
Flow Acceleration ◽  
Adhesive Proteins

Blood flow profoundly varies throughout the vascular tree due to its pulsatile nature and to the complex vessel geometry. While thrombus formation has been extensively studied in vitro under steady flow, and in vivo under normal blood flow conditions, the impact of complex hemodynamics such as flow acceleration found in stenosed arteries has gained increased appreciation. We investigated the effect of flow acceleration, characterized by shear rate gradients, on the function of platelets adhering to fibrinogen, a plasma protein which plays a key role in hemostais and thrombosis. While we confirmed that under steady flow, fibrinogen only supports single platelet adhesion, we observed that under shear rate gradients, this surface becomes highly thrombogenic, supporting efficient platelet aggregation leading to occlusive thrombus formation. This shear rate gradient-driven thrombosis is biphasic with an initial step of slow platelet recruitment supported by direct plasma VWF adsorption to immobilized fibrinogen and followed by a second phase of explosive thrombosis initiated by VWF fiber formation on platelet monolayers. In vivo experiments confirmed that shear rate gradients accelerate thrombosis in a VWF-dependent manner. Together, this study characterizes a process of plasma VWF-dependent accelerated thrombosis on immobilized fibrinogen in the presence of shear rate gradients.

Dilator response of rat mesenteric arcading arterioles to increased blood flow velocity

1989 ◽  
Vol 257 (6) ◽  
pp. H1958-H1965 ◽  
Author(s):  
V. Smiesko ◽  
D. J. Lang ◽  
P. C. Johnson
Keyword(s):  
Collateral Flow ◽  
Red Cell ◽  
Average Delay ◽  
Velocity Increase ◽  
Rat Mesentery ◽  
Cell Velocity ◽  
Flow Through ◽  
Red Cell Velocity ◽  
Increased Blood Flow

Arcading arterioles (average diam 68 microns ID) connecting adjacent triangular vascular sectors in the rat mesentery were examined in vivo for the presence of flow-dependent vasodilation. When a feed artery to one of these sectors was occluded, the affected sector was supplied by collateral flow through the arcading arteriole, and red cell velocity in the arteriole increased by 10-66 mm/s. The velocity increase was followed (with an average delay of 7.7 s) by dilation of the arcading arteriole, which averaged 68%. The dilation was closely correlated with red cell velocity (r = 0.96), volume flow (r = 0.96), and wall shear rate (r = 0.89). The dilation was sustained for the duration of increased velocity (1-10 min) and was not affected when direction of flow in the arteriole was reversed. The flow-induced dilation was equal to the maximal dilation attained with topically applied papaverine. Dilation of the arcading arteriole could be almost completely abolished if the arteriole was also occluded during occlusion of a feed artery. These observations indicate that a potent flow-dependent dilator mechanism is present in arcading arterioles of rat mesentery and may play an important role in local regulation.

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