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Biomedical subjects

M Intaglietta

Publications and source records attributed to M Intaglietta.

At least 127 records · Page 7Linked to original sources
PubMed1983

Spontaneous arteriolar vasomotion as a determinant of peripheral vascular resistance.

Spontaneous changes of diameter in small arteries and arterioles were studied in the hamster skin fold chamber preparation, which allows to observe the microcirculation without acute exposure and anesthesia. Continuous measurements of diameter were made when the preparation appeared to be physiologically normal according to preset criteria. 89% of the arterial vessels studied showed spontaneous changes in diameter. The activity was prevalently periodic with 29% of the vessels exhibiting random changes in diameter. The amplitude of the periodic activity expressed as a percentage of the mean diameter increases in proportion to the vessel size, arterial vessels in the 40-100 micron diameter range exhibit amplitudes of the order of 10-20%. The smallest arterioles show changes as large as 100% of mean diameter, which cause these vessels to become temporarily occluded. This phenomenon is analyzed in terms of its effect on peripheral vascular resistance by means of an analytical model that assumes vasomotion to be a periodic phenomenon. It is shown that the presence of time dependent changes in vessels diameter similar to those observed, has an important effect on peripheral vascular resistance.

Animals↗
PubMed1982

[Effect of the vasoactive drug buflomedil in arterial occlusive disease].

Peripheral occlusive disease is characterized by impairment of microcirculatory function in poststenotic vascular segments, independently from etiology and stage of the disease. The microcirculatory disorder results in impairment of the rheologic properties of blood, stagnation and maldistribution of nutritional flow; as a consequence local hypoxia and tissue acidosis will occur. Treatment of arterial occlusive disease in patients not amenable to surgery, therefore has to abolish the microcirculatory disorder. The vasoactive drug Buflomedil is well tolerated when administered at recommended dose and free from effects on the central hemodynamics. However, Buflomedil improves microvascular perfusion and function. This beneficial effect is the composite outcome of the drugs effect on red cell flexibility, platelet aggregation, oxygen need and redistribution of microvascular blood flow.

Animals↗
PubMed1982

The response of blood flow velocity in finger nailfold capillaries to contralateral cooling.

The present study was performed in order to determine the effect of contralateral cooling on capillary blood flow velocity (CBV) in human nailfold capillaries during rest and postocclusive reactive hyperemia. The following reactions were found: Mean resting CBV (2 min) was slightly (19%) but not significantly (p greater than 0.05) decreased by cooling of the contralateral hand. However, immediately after the hand was submerged in the cold water (15 +/- 1 degree C) there was a short (3-10 S) but marked decrease of CBV. In 3 of 7 subjects CBV stopped completely for 5-10 S. No change of the skin temperature was seen during the contralateral cooling procedure. There was an increase in periodic and intermittent flow fluctuations of CBV during contralateral cooling, which was not noticed in the digital pulse amplitude (DAPA), indicating a reflex-mediated vasoconstriction at the microcirculatory level. The peak CBV during postocclusive reactive hyperemia (PRH) response was not influenced by contralateral cooling (1.01 +/- 0.57 mm/s before and 0.98 +/- 0.4 mm/s after cooling). However, because of the decrease in mean resting CBV during contralateral cooling, the percent increase in CBV during PRH increased from 66% to 104% by the cooling procedure (p greater than 0.05).

Adult↗
PubMed1982

Vasomotion, tissue fluid flow and the formation of lymph.

Spontaneous vasomotor activity was studied in the sandwich window preparations of the subcutaneous fasciae of the dorsal skin of rats. Measurements of the periodic changes in diameter related to the length of the active vessel show that this phenomenon causes substantial periodic volumetric displacements in tissue. We propose the hypothesis that these volumetric displacements are partially made up by tissue displacement, and are partially due to displacement of the tissue fluid. The tissue fluid motion due to anteriolar vasomotion compared with the net tissue fluid motion due to fluid exchange from the corresponding number of capillaries, shows that these two effects are similar in magnitude. We propose the hypothesis that this periodic motion of fluid in the tissue constitutes an additional mechanism by which tissue fluid is propelled into the terminal lymphatics.

Animals↗
PubMed1980

Microcirculatory studies in rat mammary carcinoma. I. Transparent chamber method, development of microvasculature, and pressures in tumor vessels.

Fragments of a mammary adenocarcinoma were implanted into transparent tissue chambers in the dorsal skin flaps of female inbred F344 rats. A chamber modification permitted repeated access to the tissue without infection, vessel disruption, or impairment of tumor growth. Tumors completely filled the chambers after 26-30 days. Development of tumor microvasculature was characterized by increase in number, length, and diameter of vessels. These changes were much more pronounced in capillaries and venules than in arterioles. Direct blood pressure measurements were performed in microvessels throughout the tumor during the first 3 weeks of growth as well as in microvessels of tumor-free control preparations containing subcutaneous tissue. Average pressures in arterioles of 40- to 11-micron diameter were between 23.0 and 17.3 cm H2O in tumors versus 25.5 and 16.2 cm H2O in controls. Average pressures in venous capillaries, venules, and veins up to 150-micron diameter were between 9.1 and 8.1 cm H2O in tumors and between 13.4 and 11.0 cm H2O in controls.

Adenocarcinoma↗
PubMed1979

Effects of radiopaque contrast media on the microcirculation of the rabbit omentum.

Histamine concentration in plasma was measured and the microvasculature studied after injections of radiographic contrast materials and hypertonic NaCl solutions. Only 8 ml/kg of contrast material caused a prolonged decrease in systemic and microvascular pressure and a drop in erythrocyte velocity. Concomitantly, a significant increase in plasma histamine concentration was observed after two minutes. Signs of cellular defects and constriction of arterioles were noted after several minutes. These findings suggest that the hyperosmolality of the radiopaque materials tested could initiate the microhemodynamic reactions but is not responsible for cellular and endothelial damage in the microcirculation of the rabbit omentum.

Animals↗
PubMed1979

Blood pressure fluctuations in human nailfold capillaries.

Dynamic blood pressure was measured in 33 human finger nailfold capillaries after direct cannulation with glass micropipettes by means of a resistance servo-nulling pressure measuring method. ECG, finger pulsations, and respiratory thorax excursions were monitored simultaneously. All recordings exhibited pulsatile oscillations related to the cardiac rhythm. These oscillations resembled the wave forms of arterial pulsations with steep upstroke and dicrotic notch when the pressure amplitudes were above 10 mmHg. There was no apparent dependence on respiration. In 12 instances, pressure fluctuations with frequencies ranging from 0.2 down to 0.07 Hz were observed in both the arteriolar and venular limb. Blood pressure in human skin capillaries is pulsatile and subject to remarkable fluctuations in the arteriolar as well as in the venular limb, systolic pressure values ranging from 14 to 71 mmHg and from 11 to 52 mmHg, respectively.

Adult↗
PubMed1979

Tissue perfusion inhomogeneity during early tumor growth in rats.

Tissue perfusion in BA 1112 sarcomas of WAG inbred Rijswijk rats was determined from in vivo measurements of capillary density, length, and erythrocyte velocity in modified Algire chamber preparations. Studies were done with the use of television techniques in situ during a period of 26 days, both in control chambers and after implantation of a 0.1-mm3 piece of tumor tissue. Perfusion in control areas void of tumor tissue. Perfusion in control areas void of tumor was approximately 8-10 ml/minute/100 g of tissue. Flow in active tumor growth regions on the outward side of the tumor edge was through undifferentiated channels and had characteristics of flow through a porous medium. Despite enhanced arterial supply, the stabilized tumor microcirculation at the inward side of the growing tumor retained its perfusion rate constant (15-18 ml/min/100 g). Perfusion in central portions of the tumor was about 2-4 ml/minute/100 g during 12 days, whereas the tumor doubled in diameter. Our findings support the concept of temporal and functional blood flow inhomogeneity in the microcirculation of spreading tumors.

Animals↗
PubMed1979

Experimental and quantitative analysis of microcirculatory water exchange.

Quantitative and direct studies of microcirculatory fluid exchange phenomena provide evidence that fluid tissue balance in omentum and mesentery is achieved through lymphatic drainage. Fluid exchange in muscle appears to alternate between filtration and absorption from the capillaries in synchrony with arteriolar vasomotion. Detailed calculations show that, in the absence of hydraulic or osmotic pumping at the level of the terminal lymphatics, tissue pressures are of the order of +6 cm H2O for both visceral and muscle tissue. It is concluded that these microcirculatory beds represent two extreme types of mechanisms for achieving fluid balance, and that most other tissues, with the exception of liver and tumors, operate in between.

Animals↗
PubMed1978

Histamine release, complement consumption, and microvascular changes after radiographic contrast media infusion in rabbits.

The intravenous injection of RCM into rabbits produced dose-dependent changes in SAP, MVP, and RBCV, as well as plasma histamine and complement concentrations. After infusion of 8 ml/kg Hypaque-50, SAP dropped from 86 +/- 3 mm Hg to 50 +/- 3, MVP from 42 +/- 2 cm H2O to 26 +/- 3, and RBCV from 0.98 +/- 0.11 mm/sec to 0.37 +/- 0.13. The microvascular changes appeared 10 sec after injection and persisted for 10 to 40 min. During the course of the reaction it was observed that leukocytes adhered to the endothelial walls and red blood cells shrank and finally aggregated in the microvessels. The microvascular changes were accompanied by an increase in plasma histamine concentration, with an average of 44 ng/ml after 2 min, and a drop in total plasma CH50 by an average of 46%. Infusion of 8 ml/kg hyperosmolar saline solution (4.1 gm/dl or 1324 mOsm/L) produced initial changes in microvascular parameters which returned to normal within a few seconds. At the same time plasma histamine concentration increases slightly without changes in complement. It is concluded that the hyperosmolar properties of RCM may contribute to the initial hemodynamic changes observed after RCM infusion. However, the prolonged microcirculatory disturbances produced by RCM in rabbits appear to be a direct effect of the chemotoxicity of these compounds. Part of this chemotoxicity might result form initial release of vasoactive mediators such as histamine and activation of the complement system.

Animals↗
PubMed1977

A microscope-television system for studying flow velocity in human skin capillaries.

A noninvasive technique for studying blood flow dynamics in human skin capillaries is described. A light microscope combined with a closed-circuit TV system was used to monitor and record capillary blood flow velocity on video tape. Arterial pulsations were recorded plethysmographically and converted into video signals by modulating the position of a square, white area in the televised scene. Twelve healthy subjects were studied. The mean (+/- SD) resting capillary blood flow velocity was 0.65 +/- 0.3 mm/s at an average skin temperature of 30.4 +/- 2.3 degrees C. Spontaneous fluctuations at a frequency of 6-10 cycles/min were observed in most subjects. A well-pronounced flow pulsatile component could be demonstrated in all capillaries studied. The technique can be used in clinical practice for studying the physiology and pathophysiology of cutaneous microcirculation in man. It can be expected that the method may become an important diagnostic tool in diseases that involve disturbances of the microcirculation, such as diabetes, hypertension, and atherosclerosis.

Capillaries↗