Chronic administration of quercetin induces biomechanical and pharmacological remodeling in the rat coronary arteries.

Acute dilation brought about by the dietary flavonoid quercetin in coronary arterioles has been described earlier, but no information is available on its chronic effects. Male Wistar rats (body weight about 190 g) were divided to two groups: the quercetin-treated group (n=22) had quercetin supplementation of approximately 30 mg/kg/day, whereas the control group (n=20) had none. After eight weeks of treatment, intramural coronary arterioles with identical passive diameters (178+/-14 microm and 171+/-9 microm) were prepared and their biomechanics and pharmacological reactivities were tested using pressure arteriography ex vivo. The spontaneous tone of quercetin-treated arteries was higher (16.5+/-1.9 % vs. 12.9+/-0.9 %), which resulted in a reduced lumen size (144+/-9 microm vs. 167+/-12 microm), thicker vascular wall (22.6+/-1.8 microm vs. 17.4+/-1.6 microm) and decreased tangential wall stress (16.8+/-1.1 kPa vs. 20.5+/-1.6 kPa) in supplemented animals (in spontaneous tone at 50 mm Hg, p<0.01 in all these comparisons). Elevated basal NO release resulted in increased endothelial dilation in quercetin-treated animals, especially at higher intraluminal pressures (10.8+/-2.5 % vs. 5.7+/-1.3 % at 70 mm Hg, p<0.01). We found remodeling of the geometry of coronary arterioles to ensure higher dilatory reserve and nitrogen monoxide production, as well as lowered elastic stress of the vessel wall.

A simple standard technique for labyrinthectomy in the rat: A methodical communication with a detailed description of the surgical process.

Aims Labyrinthectomized rats are suitable models to test consequences of vestibular lesion and are widely used to study neural plasticity. We describe a combined microsurgical-chemical technique that can be routinely performed with minimum damage. Methods Caudal leaflet of the parotis is elevated. The tendinous fascia covering the bulla is opened frontally from the sternomastoid muscle's tendon while sparing facial nerve branches. A 4 mm diameter hole is drilled into the bulla's hind lower lateral wall to open the common (in rodents) mastoid-tympanic cavity. The cochlear crista (promontory) at the lower posterior part of its medial wall is identified as a bony prominence. A 1 mm diameter hole is drilled into its lower part. The perilymphatic/endolymphatic fluids with tissue debris of the Corti organ are suctioned. Ethanol is injected into the hole. Finally, 10 µL of sodium arsenite solution (50 µM/mL) is pumped into the labyrinth and left in place for 15 min. Simple closure in two layers (fascia and skin) is sufficient. Results and conclusion All rats had neurological symptoms specific for labyrinthectomy (muscle tone, body position, rotatory movements, nystagmus, central deafness). Otherwise, their behavior was unaffected, drinking and eating normally. After a few days, they learned to balance relying on visual and somatic stimuli (neuroplasticity).

Regional differences in statistical geometry of endothelial dense granules in human extremity veins.

OBJECTIVES: Leg and arm human veins are exposed to different gravitational stresses. We investigated if there is difference in the amount and geometry of secretory vesicles in their endothelium. METHODS: Superficial small vein segments were removed during vascular operations for electromicroscopic analysis. Vesicular area/total endothelial cross-sectional area was determined by computer-based morphometry. Long and short axes of granule cross sections were measured by image analyzing software. RESULTS: Vesicular density in all samples was 2.26 ± 0.34%. There was no significant difference between the vesicular densities of upper extremity and leg. The shape of the vesicles was more frequently elongated in leg than in arm sections (p < 0.01). CONCLUSIONS: The density of the vesicles does not depend on vascular region or orthostatic load. Ellipticity of these granules is significantly different in areas exposed to different gravitational stresses. This might contribute to the differences of thrombotic and hemodynamic properties of leg and upper body veins.

Comparison of passive and active biomechanical properties of human cervical and leg veins.

AIM: The aim of this study was to evaluate and compare passive and active biomechanical properties of human superficial veins exposed in vivo to different orthostatic stresses. METHODS: Superficial veins from jugular and saphenous regions were studied (11 segments each). Digitalized pressure-diameter curves were recorded in Krebs-Ringer solution, and after administration of 10-5M norepinephrine and 10-5M acetylcholine. Calcium-free solution was used to determine passive biomechanical properties. Similar tissue samples were collected for histochemistry. Resorcin-fuchsin stainings and immuno-histochemistry for smooth muscle actin were used. RESULTS: The outer radius of the relaxed samples was identical. Leg vein walls were thicker in Krebs-Ringer solution (110 ± 11 vs. 84 ± 7 µm at 30 mmHg). Isobaric wall stress was significantly higher in cervical veins. The significant differences in incremental distensibilities and elastic moduli were dependent on pressure level and smooth muscle tone. Spontaneous tone and norepinephrine induced contractions were significantly higher in leg veins (at 30 mmHg 18.3 ± 4.1 vs. 5.6 ± 1.8% and 37.6 ± 4.5 vs. 11.2 ± 4.3 %, respectively). Endothelial dilation was larger in cervical vein segments (3.8 ± 0.9% vs. 1.8 ± 0.5%). Resorcin-fuchsin and smooth muscle actin staining structures were more abundant in leg veins. CONCLUSION: Comparing active and passive biomechanical properties of human veins affected chronically by different orthostatic loading, we found several quantitative differences that reflect the physiological adaptation mechanisms to long-term gravitational stress.

Arteriolar biomechanics in a rat polycystic ovary syndrome model - effects of parallel vitamin D3 treatment.

UNLABELLED: To clarify the effects of dihydrotestosterone (DHT)-induced polycystic ovary syndrome (PCOS) on arteriolar biomechanics in a rat model and the possible modulatory role of vitamin D3. METHODS AND RESULTS: The PCOS model was induced in female Wistar rats by ten-weeks DHT treatment. Arteriolar biomechanics was tested in arterioles by pressure arteriography in control as well as DHT- and DHT with vitamin D3-treated animals in contracted and passive conditions. Increased wall stress and distensibility as well as increased vascular lumen were detected after DHT treatment. Concomitant vitamin D3 treatment lowered the mechanical load of the arterioles and restored the vascular diameter. CONCLUSION: The hyperandrogenic state resulted in more rigid, less flexible arteriolar walls with increased vascular lumen compared with controls. DHT treatment caused eutrophic remodelling of gracilis arteriole. These prehypertensive alterations caused by chronic DHT treatment were mostly reversed by concomitant vitamin D3 administration.

Determination of venous blood flow velocity using digital videomicroscopy (A short methodical communication).

BACKGROUND/AIM: There is a limited number of methods to measure blood flow velocity in small veins. A cheap and simple new videomicroscopic method developed in our laboratories is described in the paper. METHODS: A stretch of the saphenous vein of the rat was exposed by careful micropreparation on the thigh of anesthetized animals. Bolus amount (approx. 5 µl) of saline was infused into a small side branch through a microcannula to dilute flowing blood. Videomicroscopic picture of the vein was then taken of the exposed upstream stretch of the vein. Serial pictures were digitized and analyzed using macro functions of the Image J software. Sensitive areas of serial pictures were selected and fitted. Consecutive pictures were subtracted from each other to better characterize their alteration in-between frames. Greyscale intensity values measured at different points of the inner diameter were averaged for each point of the vessel axis. Cross-correlations along the axis were then computed for consecutive frames with delays of 40, 80, 120 and 160 msec. Pixel offsets producing cross-correlation maxima were determined and used to compute mean flow velocity. RESULTS: Combination of digital subtraction and cross-correlation computations yielded easily identifiable maximums. Mean flow velocities could be determined with limited uncertainty. CONCLUSION: The described technique gives a cheap, simple and reproducible mean to determine mean blood flow velocities in small veins in anesthetized animals, where other current techniques (ultrasonography, laser-Doppler, fluorescently labelled red cell movement) are either expensive or can be applied with difficulty only.

Biomechanics and vasoreactivity of female intramural coronaries in angiotensin II induced hypertension.

Hypertension causes small vessel remodeling, vasomotor alterations. We investigated diameter, tone and mechanics of intramural small coronaries of female rats that received chronic angiotensin treatment to induce hypertension.Angiotensin II infusion (AII, 100 ng/bwkg/min, sc.) was used to establish hypertension in 10 female rats. Other 10 rats served as controls. Following 4 weeks of treatment, side branches of the left anterior descendant coronary (diameter approximately 200 microm) were isolated, cannulated and pressure-diameter curves were registered between 2-90 mmHg. Changes in vessel diameter were measured in Krebs solution, in the presence of thromboxane A2 receptor agonist (U46619, 10(-6) M), bradykinin (BK, 10(-6) M), and finally at complete relaxation (in Ca2+-free solution). Chronic AII treatment raised the mean arterial pressure (130+/-5 mmHg vs. 96+/-2 mmHg, average +/-SEM) significantly. Wall thickness of the AII group was significantly greater (40.2+/-4.2 microm vs. 31.4+/-2.7 microm at 50 mmHg in Ca2+ -free solution), but cross-section of the vessel wall did not differ. Tangentional wall stress and elastic modulus decreased significantly in hypertensive animals. Constrictions in the presence of U46619 were greater in the AII group (24.4+/- 5.6% vs. 14.5+/-3.3% at 50 mmHg). In hypertension, intramural small coronaries showed inward eutrophic remodeling, as a morphological adaptation following AII treatment enhanced thromboxane A2-induced tone.

Maintained geometry, elasticity and contractility of human saphenous vein segments stored in a complex tissue culture medium.

OBJECTIVE: Improved maintenance of endothelial function and higher viability of saphenous vein grafts stored in a complex tissue culture medium (TCM) have been demonstrated. This article studies the biomechanical properties of saphenous vein segments. DESIGN: Biomechanical properties of 72 saphenous vein segments remaining from coronary bypass grafting of 32 patients have been studied after different storage procedures. MATERIALS: The materials studied included fresh segments, segments stored in a cooled conventional physiological salt solution (normal Krebs-Ringer (nKR)) for 1-2 weeks, segments stored in a cooled chemically defined TCM (X-Vivo) for 1,2,3 and 4 weeks and segments cryopreserved for a few weeks. METHODS: Specimens were cannulated at both ends and pressure-diameter curves were recorded in the 0-85-mmHg range in nKR with 10 microM norepinephrine added to induce maximum smooth muscle contraction, as well as in Ca(2+)-free medium to induce full relaxation. Tensile strength was checked at 300 mmHg. Distensibility, elastic modulus and active strain were computed. RESULTS: Segments stored in nKR dilated morphologically, their distensibility decreased and they lost their ability to contract (1.5+/-0.7% from 10.1+/-1.5% of control) in 1 week. The TCM-stored segments preserved their contractility until 1 week, and this parameter only slowly decreased afterwards (first week, 11.5+/-7.3%; fourth week, 3.9+/-0.6%). There was a slight decrease in wall thickness but the lumen diameter was not affected. The elastic parameters of these segments were practically identical to those of fresh segments. Cryopreserved segments narrowed morphologically, their wall thickened and contractility diminished. CONCLUSIONS: Storage in TCM helps preserve the passive and active biomechanical properties of human saphenous vein segments. Such properties can be expected to improve graft tissue viability.

Vestibular control of intermediate- and long-term cardiovascular responses to experimental orthostasis.

Sustained orthostasis elicits the elevation of arterial blood pressure (BP) via sympathetic activation in conscious Wistar rats for at least 2 hours. We tested the hypothesis whether vestibular apparatus plays a role in BP and heart rate (HR) control in response to prolonged gravitational stress. BP and HR responses to 45 degrees head-up for either 2 or 24 hours were monitored by telemetry. Vestibular lesions (VL) were performed by a modified microsurgical-chemical technique. Horizontal BP and HR were not influenced by VL preceding 2-hour tilt. VL abolished the sustained 2-hour BP response to head-up tilt (8.3+/-0.9 mm Hg relative to horizontal values) while suppressed HR transiently only. VL eliminated diurnal BP fluctuations and decreased HR in horizontal position for 24 hours. Head-up tilt for 24 hours increased BP and HR progressively in intact animals, raising their daily average value by 5.6+/-0.7 mm Hg and 22.2+/-6 BPM, respectively. VL resulted in an initial BP rise followed by progressive BP reduction in response to long-term head-up tilt (4+/-2.2 mm Hg) without eliminating the tachycardia (34.4+/-5.4 BPM). Thus, blockade of labyrinthine inputs attenuates the BP responses elicited by both intermediate and long-term gravitational stress of orthostatic type. However, other sensory inputs derived from non-vestibular cues (e.g. proprioceptive, visual, visceral, cutaneous etc.) seem to be effective enough to maintain BP normal.

Ureteral motility.

The pyeloureteral function is to transport urine from the kidneys into the ureter toward the urinary bladder for storage until micturition. A set of mechanisms collaborates to achieve this purpose: the basic process regulating ureteral peristalsis is myogenic, initiated by active pacemaker cells located in the renal pelvis. Great emphasis has been given to hydrodynamic factors, such as urine flow rate in determining the size and pattern of urine boluses which, in turn, affect the mechanical aspects of peristaltic rhythm, rate, amplitude, and baseline pressure. Neurogenic contribution is thought to be limited to play a modulatory role in ureteral peristalsis. The myogenic theory of ureteral peristalsis can be traced back to Engelmann (1) who was able to localize the peristaltic pressure wave's origin in the renal pelvis and suggested that the ureteral contraction impulse passes from one ureteral cell to another, the whole ureter working as a functional syncitium. Recent studies of ureteral biomechanics, smooth muscle cell electrophysiology, membrane ionic currents, cytoskeletal components and pharmacophysiology much improved our understanding of the mechanism of how the urine bolus is propelled, how this process is disturbed in pathological states, and what could be done to improve it.

Does long-term experimental antiorthostasis lead to cardiovascular deconditioning in the rat?

Microgravity or simulated microgravity induces acute and chronic cardiovascular responses, whose mechanism is pivotal for understanding of physiological adaptation and pathophysiological consequences. We investigated hemodynamic responses of conscious Wistar rats to 45? head-down tilt (HDT) for 7 days. Arterial blood pressure (BP) was recorded by telemetry. Heart rate (HR), spectral properties and the spontaneous baroreflex sensitivity (sBRS) were calculated. Head-up tilt (HUT) was applied for 2 h before and after HDT to assess the degree of any possible cardiovascular deconditioning. Horizontal control BP and HR were 112.5+/-2.8 mmHg and 344.7+/-10 bpm, respectively. HDT elicited an elevation in BP and HR by 8.3 % and 8.8 %, respectively, in less than 1 h. These elevations in BP and HR were maintained for 2 and 3 days, respectively, and then normalized. Heart rate variability was unchanged, while sBRS was permanently reduced from the beginning of HDT (1.01+/-0.08 vs. 0.74+/-0.05 ms/mmHg). HUT tests before and after HDT resulted in BP elevations (6.9 vs. 11.6 %) and sBRS reduction (0.44 vs. 0.37 ms/mmHg), respectively. The pressor response during the post-HDT HUT test was accompanied by tachycardia (13.7 %). In conclusion, chronic HDT does not lead to symptoms of cardiovascular deconditioning. However the depressed sBRS and tachycardic response seen during the post-HDT HUT test may indicate disturbances in cardiovascular control.

Generalized alterations in the biomechanical properties of large veins in non-thrombotic thrombophilic young patients.

AIM: In young, post-thrombotic patients, venous distensibility is decreased not only in the affected lower limb, but also in the contralateral limb and in the jugular vein when compared to age-matched control subjects. In the present study, we investigated venous wall mechanical properties in young, asymptomatic thrombophilic patients. METHODS: Eleven young (24+/-0.4 years) control subjects and 9 age-matched patients (21.1+/-1.8 years) with proven thrombophilic molecular defects, but without any signs or history of previous deep vein thrombosis, were compared. Anterolateral and mediolateral diameters of the common femoral, axillary and internal jugular veins were measured by ultrasonography in situ. Pressure alterations were induced by altering body positions and by pressure-controlled Valsalva tests. Distensibility was calculated from diameter and pressure changes. RESULTS: In thrombophilic patients, resting diameter of both the common femoral and of internal jugular veins at low transmural pressure was larger than those for the control subjects. Distensibility, however, was significantly less when high pressures were applied. Alterations in diameter of the axillary vein were minimal. CONCLUSION: Our measurements suggest that there are generalized changes in venous mechanical properties in thrombophilic patients even before the appearance of thrombotic processes. These biomechanical alterations of the venous wall and/or surrounding connective tissue are similar to those found in connection with aging and in post-thrombotic patients. The pathological mechanisms behind these processes are unknown.

Increased diameter and enhanced myogenic response of saphenous vein induced by two-week experimental orthostasis are reversible.

Previously, increased diameter and enhanced myogenic tone were seen after 2-week 45o head-up (HUT2) in the rat. We studied the reversibility and the effect of extended tilt on this phenomenon using two experimental groups: HUT2 plus 2-week horizontal (HUT2HOR2), and 4-week tilting (HUT4). 4-weeks in normal cages (NC4) served as control. Diameter of saphenous vein (SV) in 2-20 mm Hg pressure range, wall and media thickness, endothelial and smooth muscle cell densities, and cell proliferation were measured. The diameter of SV from HUT4 was significantly larger compared with HUT2HOR2 or NC4 within the whole pressure range both in Krebs-Ringer (870.4+/-21.3 vs. 778.2+/-24.9 and 771.6+/-28.1 microm at 10 mm Hg, respectively) and in Ca(2+)-free solution. Myogenic and norepinephrine-induced vascular tone, wall and media thickness did not differ among the three groups. Endothelial cell density decreased in HUT4 (10.7+/-1.2) vs. HUT2HOR2 (15.1+/-1.0) and NC4 (15.3+/-0.6), while that of smooth muscle was unchanged. No cell proliferation marker was seen. In conclusion, both increased diameter and enhanced myogenic tone of SV seen in HUT2 proved to be reversible. HUT4 resulted in increased SV diameter, similarly to HUT2, however, vascular tone was not amplified. This suggests that a prolonged orthostatic load may readjust the function of smooth muscle.

Does chronic experimental head-down tilt alter intramural innervation density of limb blood vessels?

Earlier, substantial increases in the intramural sympathetic innervation density of rat hind-limb blood vessels were found after 2 weeks of experimental orthostasis with tubular 45 degrees head-up tilt cages. In the present study, we presumed that chronic head-down tilting induces opposite changes in the innervation density. Tilted rats were kept 45 degrees head-down in long tubular cages for either 2 or 4 weeks (HDT2, HDT4), and the control animals were maintained in horizontal tilt cages for the same period (HOR2, HOR4). Segments of the saphenous and brachial veins and arteries were used for quantitative electron microscopic examinations. Intramural innervation density was defined by nerve terminal density (NTD) and synaptic microvesicle count (SVC) within the vascular adventitia. Neither HDT2 nor HDT4 resulted in a decrease of NTD or SVC of the saphenous and brachial veins or arteries; instead, a tendency to increase was observed in some cases. Thus in contrast to the large increases we found earlier in hind-limb vascular innervation density after 2 weeks of head-up tilting, head-down tilting of the same duration-or even twice as long-did not decrease the adventitial innervation density in our model. We assume that the quasi-free locomotor exercise the tilted animals in the long tubular cages were allowed may counteract a possible suppressive effect of chronic head-down tilt on hind-limb vascular innervation density.

A historical chronology of teaching physiological sciences to medical students in Hungary.

Starting from the second half of the 18th century, a brief chronology of teaching medical physiology and pathophysiology in Hungary is given in this article. Even when the major milestones of this history are only identified, one can recognize several significant achivements that may inspire the present and coming generations to develope and enrich this inheritance of high values. These achivements involve--inter alia--influential scientific "schools" founded by eminent professors, outstanding institutions of basic medicine, recognition of the relevance of the integrative approach in medical education, close relationship between teaching and scientific research, high-standard theoretical and practical training, teaching based on excellent domestic and foreign textbooks, extensive international relationships and experience.

Remodeling of the rat saphenous vein network in response to long-term gravitational load.

Our main objective was to test whether chronic orthostatic body position induces network changes in the saphenous vein superficial tributary system of the rat. Fourteen male Sprague-Dawley rats were kept in tilted tube cages (45-degree head-up position) for two weeks to induce chronic gravitational load to their leg veins. Ten animals housed in normal cages and four animals kept in horizontally positioned tube cages served as controls. The whole superficial network of the left saphenous vein was microprepared surgically under anesthesia, superfused with saline and observed under a videomicroscope, while normal flow and pressure were maintained in the lumen. Branching angles, lengths of venous segments and their diameters were measured offline from digitized images using special image-analyzing software. Several branching angles at the popliteal confluence were significantly reduced by 12.5-15.8 %. The in vivo diameter of the main branch (936+/-34 vs. 805+/-44 microm) and of one of the popliteal tributaries (776+/-38 vs. 635+/-36 microm) increased (p<0.05), comparing vessels from tilted animals with those from normal controls. Maintaining the animals in horizontal tube cages did not induce the above alterations. The increased diameters and reduced branching angles of the saphenous vein network observed are adaptive responses of the venous network to a long-term gravitational load.

Semmelweis' discovery and its Finnish follow-up.

Professor Ignác Semmelweis (1818-1865) is one of the great personalities of medical history. He insisted on washing hands with chlorine water before any obstetrical intervention, he was the first to demonstrate its importance in preventing puerperal fever. Thus, the principle of asepsis was introduced prior to the discovery of bacteria and bacterial diseases. Semmelweis carefully documented his findings and in this way pioneered the scientific analysis of clinical data Medical community of that time misinterpreted Semmelweis' great ideas, he died abandoned and forgotten. A Finnish doctor Josef Adam Joachim Pippingsköld was one of the first obstetricians who had realized the importance of Semmelweis' work. In 1861, in his letter to Semmelweis he reported about his own findings and favorable results in prevention of puerperal fever in Helsinki. Two decades earlier, Dr. Ehrström in the University of Helsinki had submitted his thesis on pathophysiology of puerperal fever that was similar to the ideas of Semmelweis. Long before modern times in Finland, mothers traditionally had their babies delivered in smoke saunas, where heating and smoke of bactericidal phenols created a clean, rather aseptic environment. Hand washing was self-evident necessity. However, the situation was quite different in the Central European universities and departments of obstetrics, where the medical training and clinical practice took place side by side. Semmelweis' life and his contribution to medicine was appreciated even in the theatrical circles of Finland. The piece "Semmelweis" of Norwegian playwright Jens Bjørneboe got its World Premier in the Swedish Theatre in Turku, former capital of Finland, in September 1969.

Influence of long-term experimental orthostatic body position on innervation density in extremity vessels.

The aim of this study was to quantitate the density of nerve terminals as well as their synaptic vesicle population in the adventitia of saphenous (SV and SA) and brachial veins and arteries (BV and BA) obtained from rats maintained in a horizontal control or a tilted position. Adult animals were kept individually in tube-like cages in a 45 degrees head-up position. After 2 wk, both tilted and control animals were anesthetized, and the whole body was perfused with fixative solution at physiological pressure. Vessels segments were then excised for electron microscopy and immunohistochemistry. The nerve terminal density (NTD) of SA was 8.20 +/- 1.46 nerve terminals/100 microm(2) cross section of adventitia and that of SV was 4.53 +/- 0.61 nerve terminals/100 microm(2) cross section of adventitia in control rats. Tilting caused a significant increase in NTD of both SA (70%) and SV (52%). The synaptic microvesicle density (SyVD) was larger in SA than SV in control rats (30.48 +/- 4.41 vs. 13.38 +/- 2.61 synaptic vesicles/10 terminal sections), but tilting resulted in more pronounced changes in SyVD of SV (95%) than SA (54%). No significant changes in NTD and SyVD of BA were found after tilt (-3.6% relative to 4.99 +/- 0.33 compared with 0.4% relative to 24.89 +/- 3.7, respectively). Whereas NTD of BV exhibited a tendency to increase (3.73 +/- 0.86 vs. 2.31 +/- 0.29 nerve terminals/100 microm(2) cross section of adventitia), SyVD did not change significantly (18.96 +/- 2.74 vs. 22.85 +/- 3.17 synaptic vesicles/10 terminal sections). A large number of nerve terminals of all vessels were tyrosine hydroxylase immunoreactive (containing norepinephrine). These findings support the hypothesis that long-term gravitational load causes adaptive morphological and functional remodeling of sympathetic innervation in blood vessels of the extremities.