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Biomedical subjects

A Colantuoni

Publications and source records attributed to A Colantuoni.

At least 37 records · Page 2Linked to original sources
PubMed1993

Effect of leukocyte adhesion and microvascular permeability on capillary perfusion during ischemia-reperfusion injury in hamster cheek pouch.

The role of leukocyte sticking and permeability changes in the variation of perfused capillaries induced by ischemia reperfusion was studied in the hamster cheek pouch microcirculation. The drugs utilized were the antiperoxidative agents allopurinol, the calcium antagonists verapamil and diltiazem, and phenidone and adenosine, which inhibit leukotriene formation as well as leukocyte adhesion to the endothelium. The microvasculature was visualized by a fluorescence technique. Ischemia was induced by clamping the cheek pouch for 30 minutes followed by 30 minutes of reperfusion. The increase in permeability, the perfused capillary length and the number of adhering leukocytes to venular vessel wall were measured. Ischemia and reperfusion were associated with increased permeability, increased number of leukocytes sticking to the venular wall, and decreased number of functional capillaries. Microvascular injury evidenced by increased permeability was apparent in the first 5 min of ischemia. All the drugs decreased the number of leukocytes sticking to the venular wall; allopurinol, verapamil and adenosine reduced the increase in permeability, whereas phenidone and diltiazem were effective only during ischemia. In addition verapamil and adenosine preserved capillary blood flow during reperfusion. In conclusion, leukocyte sticking is correlated with increased microvascular permeability, but not with decreased perfusion of the capillary bed. These data suggest that leukocytes did not play a prominent role in the reduction of functional capillaries at the end of reperfusion.

Adenosine↗
PubMed1993

Biological zero of laser Doppler fluxmetry: microcirculatory correlates in the hamster cheek pouch during flow and no flow conditions.

The microcirculation of the hamster cheek pouch was visualized by the intravenous injection of FITC-dextran 150,000 during normal flow conditions and when flow was interrupted by clamping proximal to the pouch. Laser Doppler fluxmetry (LDF) was used to evaluate flow during control, 30 min of occlusion and after reperfusion. Intravital video recordings of the microcirculation during occlusion show that blood moves between the different arteriolar segments after occlusion and during the whole period of no flow. This motion was oscillatory in nature, had maximum velocity of order of 30 microns sec-1, and was related to progressive decrease of arteriolar diameter. The LDF output was in the range of 60-100 AU during control. This value fell in the range of 5-25 +/- 15% AU during occlusion and was assumed to constitute the biological zero for this system. The variability of the LDF signals was characterized by the autoregressive modeling power spectrum technique. The power spectra during control, occlusion, and reperfusion were similar, suggesting that motion of blood not related to perfusion or blood flow is present in all conditions. These findings suggest that the biological zero arises from signals that are not flow related and that it should be subtracted from the flow signal.

Animals↗
PubMed1991

Hypoxia- or hyperoxia-induced changes in arteriolar vasomotion in skeletal muscle microcirculation.

Arteriolar vasomotion was characterized in the skin muscle of the unanesthetized hamster skinfold window preparation and related to the specific arterioles that give rise to the different types of activity. The arterioles were classified according to the Strahler method: order 0 was assigned to capillaries and order 4 to the largest arterioles. The arterioles showed vasomotion with a specific range of frequencies that varied according to the vessel order; the highest fundamental frequency (9.1 +/- 3.9 cycles/min) was detected in the smallest order 1 arterioles and the lowest frequency (2.1 +/- 0.9 cycles/min) in order 4 vessels. Hypoxia (8, 11, and 15% O2 gas mixture inspiration) increased the frequency of vasomotion, decreased mean and effective diameters, and reduced capillary blood flow. The effects were more pronounced with an 8 and 11% O2 gas mixture. Hypoxia caused high-frequency vasomotion to shift from order 1 and 2 arterioles to the beginning of order 3 arterioles, which in this condition dominated the daughter vessels and generated the prominent activity (24 +/- 4 cycles/min, 11% O2 gas mixture). Hypertoxia (100% O2) induced differentiated arteriolar responses. The smallest vessels showed prolonged constriction, decreased mean and effective diameters, and reduced frequency of vasomotion. Capillary blood flow was restricted. Order 3 vessels did not constrict or dilate.

Animals↗
PubMed1991

Effects of Vaccinium Myrtillus anthocyanosides on arterial vasomotion.

The effects of Vaccinium Myrtillus anthocyanosides (Myrtocyan, VMA; CAS 84082-34-8) on arteriolar vasomotion were assessed in cheek pouch microcirculation of anesthetized hamsters and in skeletal muscle microvasculature of unanesthetized hamster skin fold window preparation. Intravenously injected VMA induced vasomotion in cheek pouch arterioles and terminal arterioles with higher frequency in smaller vessels. In the skeletal muscle arteriolar networks VMA increased vasomotion frequency and amplitude in all vessel orders. The results indicate that VMA are effective in promoting and enhancing arteriolar rhythmic diameter changes, that play a role in the redistribution of microvascular blood flow and interstitial fluid formation.

Animals↗
PubMed1990

Superposition of arteriolar vasomotion waves and regulation of blood flow in skeletal muscle microcirculation.

In skin muscle microcirculation of Syrian hamsters, rhythmic diameter changes were studied along the arteriolar network, under normoxic conditions, at rest. A teflon coated-aluminum chamber was implanted in the dorsum skin of animals. The microcirculation was investigated using intravital microscopy technique. Vessel diameters were determined by a computer-assisted method. Power spectrum analysis of vasomotion recordings was carried out with Fast Fourier Transform and Autoregressive modelling. To determine vasomotion waveform spreading, cross-spectral data (amplitude and phase) were computed, using the modified periodogram method (FFT). The arterioles were classified according to Strahler's method. Order 1 vessels (diameter: 7.50 +/- 1.16 microns) showed the highest frequency, 4-15 cycles per min, and percentage amplitude in the range 60-100%. Order 2 and 3 arterioles had intermediate frequencies, and amplitude in the range 50-100%, and 15-50%, respectively. The largest order 4 vessels (diameter: 28.97 +/- 9.55 microns) had the lowest frequency, 0.3-3 cpm, and amplitude in the range 5-20%. In most networks, cross-correlation analysis revealed two groups of frequency components. Low frequency group was propagated from order 4 and 3 vessels downstream. High frequency components were transmitted upstream from order 1 and 2 arterioles. Therefore, a complex superposition of waveforms resulted from the activity of discrete points along the microvasculature. In conclusion, rhythmic diameter changes of arterioles in skeletal muscle microcirculation regulate blood flow distribution in capillary units and control tissue oxygenation.

Animals↗
PubMed1988

Functional microangiopathy in alloxan-treated Syrian hamsters.

Intraperitoneally injected alloxan determined long term hyperglycemia in a group of Syrian hamsters (35 hyperglycemic hamsters); transitory hyperglycemia, with recovery of normal blood glucose concentration but impairment of glucose tolerance test, was observed in a second group of alloxan-treated animals (70 normoglycemic hamsters). Microvascular permeability by fluorescent microscopy technique, capillary basement membrane thickening and pancreatic islet B, A, and D cell degranulation by computer-assisted microdensitometry were studied in Syrian hamsters at different intervals (30, 40, 60, 90, and 120 days) after intraperitoneal alloxan administration. Hyperglycemic groups showed increased permeability of venous microvasculature to high molecular weight dextran in 50%, 71.4%, and 100% of animals studied at 30, 40, and 60, 90, 120 days from treatment, respectively; indeed, they revealed pancreatic islet B cell degranulation and no capillary basement membrane thickening. Normoglycemic groups presented increased venular leakage in 28.5%, 42.8%, 71.4%, and 100% of animals investigated at 40, 60, 90, and 120 days after treatment, respectively; moreover, they showed moderate pancreatic islet B cell degranulation and no capillary basement membrane thickening. In conclusion, more severe microvascular alterations seemed to be related to more severe impairment of glucose metabolism and to longer duration of diabetes; even in normoglycemic hamsters with pathological glucose tolerance test, enhanced permeability developed.

Animals↗
PubMed1987

Increased permeability of hamster microcirculation to glycosylated albumin.

The permeability of the microcirculation to native and glycosylated albumin was tested in 25 non-diabetic Syrian hamsters. The microvasculature of the cheek pouch was studied by a fluorescent video-microscopy technique after the animals had been injected with fluorescent native or glycosylated albumin or with both. Native albumin remained in the cheek pouch microvasculature, whereas glycosylated albumin leaked out of the microvascular bed along the postcapillary and collecting venules. The extravascular leakage of glycosylated albumin, probably due to its electrical or conformational change, may represent the initial event in the development of diabetic microangiopathy.

Animals↗
PubMed1985

Variations of rhythmic diameter changes at the arterial microvascular bifurcations.

The variation of the pattern of the rhythmic diameter changes, in the hamster skin fold window preparation, was studied sequentially along the branching network of the arterial vessels, from A1 small arteries (70-100 micron diameter) to A4 terminal arterioles (less than 15 micron diameter). Contraction and dilation waveforms were characterized at all subsequent levels of bifurcation. The frequency of vasomotion was determined by a specialized spectral method called PRONY, which approximates the spectral composition of complex waveforms by the least square criteria and estimates the coefficient of correlation between reconstructed and original data. It was found that the frequency of vasomotion changes abruptly at the branching points, systematically increasing in the downstream direction. The power spectrum showed that the frequencies, which appear to originate at the bifurcations and have maximum amplitude at these points, are also found in the upstream waveforms. The downstream propagation of contractions and dilations causes superposition of waves. Thus the pattern of vasomotion is the composite effect of signals that originate at various branching points and spread downstream and upstream in the microvasculature. It seems likely to suggest that single unit smooth muscle cells, located at the branchings (local pacemakers), control the arterial rhythmic diameter changes. This time dependent phenomenon affects deeply the microvascular blood flow.

Animals↗
PubMed1985

Microvessel diameter changes during hemorrhagic shock in unanesthetized hamsters.

The effects of hypovolemic shock on the time-dependent diameter changes of small arteries and arterioles were studied in the hamster skin fold window preparation. This experimental model permits the visualization of the microvasculature without the effects of acute surgery, anesthesia, and exposure. In these conditions, all the arterial microvessels showed vasomotion, while the venules and small veins, that were also studied, did not show rhythmic diameter changes. Hemorrhage was induced by the withdrawal of blood through a chronically implanted arterial catheter. The mean arterial blood pressure was reduced to 40 mm Hg in 20 min, and was maintained at this value for an additional 30-min period. Reinfusion of the withdrawn blood was made at 50 min. During the shock period, vasomotion disappeared in all arterial vessels. The small arteries and arterioles, A1 (70-100 micron, mean diameter), A2 (40-70 micron, md), and A3 (15-40 micron, md), contracted by 20 +/- 7, 33 +/- 10, and 34 +/- 11% of the control mean diameter, respectively. A4 terminal arterioles (less than 15 micron, md) dilated after the onset of bleeding; their rhythmic diameter changes subsequently stopped and their mean diameter increased by 75 +/- 7% of the original value. V1 small veins (150-200 micron, md) contracted during shock, while V2 (35-55 micron, md), V3 (25-35 micron, md), and V4 (15-25 micron, md) venous vessels did not show any significant change. Reinfusion of shed blood caused the reappearance of vasomotion; control vasomotion patterns recovered after reinfusion. Our results indicate that the microcirculatory responses to hypovolemic shock are dependent on the vessel type; this inhomogeneous reactivity may be due to the different responsiveness of microvessels to the mechanisms elicited by hemorrhage.

Animals↗
PubMed1984

The effects of alpha- or beta-adrenergic receptor agonists and antagonists and calcium entry blockers on the spontaneous vasomotion.

The effects of systemic injections of vasoactive substances were studied in the micro-circulation of the hamster skin fold window preparation, which can be observed without anesthesia, exposure, and acute surgical procedures. The effects were characterized by the continuous measurement of the diameter of the arterial microvessels ranging from 100 to 8 micron. Power spectrum analysis was utilized to determine the frequency and the amplitude of the fundamental component of spontaneous diameter changes. Epinephrine and norepinephrine increased the frequency of vasomotion and reduced mean diameter at low dosages. Phentolamine reduced the frequency of vasomotion and increased mean diameter. Propranolol increased the frequency of vasomotion and did not significantly change mean diameter. Adenosine and verapamil suppressed vasomotion and increased mean diameter. These results are explained by postulating that low-dosage alpha-adrenergic receptor stimulation facilitates the spontaneous discharge of smooth muscle cells; beta-adrenergic receptor stimulation has the opposite effect, whereas beta-adrenergic receptor inhibition also enhances the vasomotor effect. Calcium entry blockers abolish the rhythmic discharge. This explanation of the activity of the various substances supports the hypothesis that the spontaneous vasomotion of the arterial microvessels is related to the intrinsic property of smooth muscle cells.

Adrenergic alpha-Agonists↗
PubMed1984

Quantitation of rhythmic diameter changes in arterial microcirculation.

The diameter of the arterial and arteriolar blood vessels was measured as a function of time in the hamster skin fold window preparation. When the animals recovered from the surgical implantation, the diameters of the arterial microvessels exhibited a continuous rhythmic activity throughout the preparation for a period of 2 wk while the chamber was intact. The amplitude of the diameter changes was directly proportional to the mean vessel size. The frequency of this phenomenon was determined by power spectrum analysis implemented with a Fourier transform method and was found to decrease from a maximum of 9-15 cycles/min in 8- to 15-micron A4 arterioles to 1-3 cycles/min in 70- to 100-micron A1 small arteries. A1 and A4 vessels had relatively well-defined characteristic fundamental frequencies, whereas A2 and A3 vessels showed a power spectrum that included the frequencies present in A1 and A4 vessels. The activity was not synchronized throughout the microvasculature, and frequencies and amplitudes of diameter variations changed at branching points. Anesthesia induced by the intravenous injections of pentobarbital and chloralose-urethan invariably stopped this activity throughout the preparation. The distribution of this time-dependent activity and the nature of the effect of the anesthetics suggests that this phenomenon is due to local pacemaker activity of groups of unitary smooth muscle cells.

Animals↗
PubMed1984

Effects of anesthesia on the spontaneous activity of the microvasculature.

The effects of pentobarbital, alpha-chloralose, alphaxalone-alphadolone, diethyl ether and chloralose-urethane anesthesia on microvascular vasomotion were studied in the hamster skin fold window preparation. All these agents paralyzed vasomotion in the arterioles causing an initial vasodilation, where diameters were above the control-unanesthetized mean values (UMD) for a period of 5-60 min and returned to UMD, and lower, after periods up to 90 min depending on the type of anesthetic. During chloralose-urethane anesthesia vasodilation lasted until the end of observation (90 min). The responses were quantitatively different as a function of vessel type, being more pronounced in the smaller terminal arterioles. Vasomotion did not recover at the end of anesthesia, when the animals awoke, and the vessels tended to remain inert for periods up to 10-20 min, at which time the activity was reestablished with the same control fundamental frequency. Small veins and venules did not exhibit vasomotion and showed various reactions that were characteristic for each anesthetic and vessel type, where vasodilation was the prevalent feature during pentobarbital anesthesia while diethyl ether had the opposite effect. Venular microvessels recovered control diameters 10-20 min after awakening.

Anesthetics↗
PubMed1980

[Erythrocyte deformability determined by filtration].

Authors studied red blood cell filtrability by means of an original apparatus. The red blood cells were suspended in 0,9% NaCl and Teitel solutions. Teitel solution was the most usefullness in filtrability studies.

Erythrocytes↗
PubMed1980

[Erythrocyte deformability dependent on variations in pH].

Authors studied the influence of pH changes on red blood cell deformability by means of filtration technique. In 0,9% NaCl solutions, there was decrease of RBC deformability upon both lowering and increasing of pH. In Teitel solutions, RBC deformability increased on alcalyne pH.

Erythrocytes↗
PubMed1979

[Oxygen consumption in organs of rats treated with serotonin].

The serotonin injected intraperitoneally in rats (20 mg/Kg of body weight) increases the oxygen utilization of slices of heart, liver and muscle with a maximum value after 60 min from the injection. The serotonin, probably, acts on intracellular metabolism increasing some enzymatic activities or metabolic pathways.

Animals↗