A rate-sensitive component to the myogenic response is absent from bat wing arterioles

1989 ◽  
Vol 256 (1) ◽  
pp. H32-H40 ◽  
Author(s):  
M. J. Davis ◽  
P. J. Sikes
Keyword(s):  
Transmural Pressure ◽  
The Body ◽  
Myogenic Response ◽  
Transient Pressure ◽  
Arteriolar Resistance ◽  
Pressure Changes ◽  
Bat Wing ◽  
Microscopic Techniques ◽  
Rapid Pressure ◽  
Made In

The responses of three sequential branching orders of arterioles in the bat wing to rapid and slow changes in transmural pressure were studied. Arterial and venous pressures to the wing were elevated simultaneously by pressurizing a box containing the body of the animal, while the wing was exposed to atmospheric pressure. Box pressure was elevated from 0 to +48 mmHg at two rates: 24 and 0.6 mmHg/s. During this time, continuous recordings of hydrostatic pressure and diameter were made in single arterioles using intravital microscopic techniques. Second-order arterioles and arcuate arterioles from skin and skeletal muscle constricted in response to elevated transmural pressure but did not show an enhanced response to rapid pressure changes. There was a trend for terminal arterioles to show a transient peak constriction during rapid stretch, but this response was always associated with a biphasic change in arteriolar pressure. These results suggest that the transient arteriolar resistance changes associated with rapid transmural pressure increases in previous experiments may be primarily a result of transient pressure changes in small arterioles. We find no evidence that arterioles in this preparation exhibit a rate-sensitive component to their myogenic response.

Modulation of bat wing venule contraction by transmural pressure changes

1992 ◽  
Vol 262 (3) ◽  
pp. H625-H634 ◽  
Author(s):  
M. J. Davis ◽  
X. Shi ◽  
P. J. Sikes
Keyword(s):  
Venous Pressure ◽  
Transmural Pressure ◽  
The Body ◽  
Intraluminal Pressure ◽  
Positive Pressure ◽  
Cross Sectional ◽  
Series Of Experiments ◽  
Pressure Changes ◽  
Bat Wing

We tested the hypothesis that the frequency and amplitude of spontaneous venular contractions in the bat wing could be modulated by changes in transmural pressure. In one series of experiments, venous pressure in the wing was elevated by pressurizing a box containing the body of the animal while the wing was exposed to atmospheric pressure. During this time, venular diameters were continuously recorded using intravital microscopic techniques while venular pressures were measured through servo-null micropipettes. In another series of experiments, single venular segments were dissected from the wing, cannulated, and pressurized in vitro. The results from both experimental protocols were qualitatively similar; alterations in venous pressure over a narrow range (+/- 5 cmH2O from control) produced substantial changes in contraction frequency and amplitude. The product of frequency and cross-sectional area was maximal over the venous pressure range between 10 and 15 cmH2O. Venules demonstrated a rate-sensitive component in their reaction to rapid pressure changes, because contraction bursts occurred immediately after positive pressure steps and quiescent periods often occurred after negative pressure steps. We conclude that venular vasomotion in the bat wing is modulated by intraluminal pressure and involves a bidirectional, rate-sensitive mechanism. In addition, comparisons with arteriolar vasomotion studies suggest that venules are more sensitive to luminal pressure changes than arterioles.

Effects of transmural pressure on brachial artery mean blood velocity dynamics in humans

2002 ◽  
Vol 93 (6) ◽  
pp. 2137-2146 ◽  
Author(s):  
Mary E. J. Lott ◽  
Michael D. Herr ◽  
Lawrence I. Sinoway
Keyword(s):  
Brachial Artery ◽  
Pressure Change ◽  
Blood Velocity ◽  
Voluntary Contraction ◽  
Transmural Pressure ◽  
Positive Pressure ◽  
Myogenic Response ◽  
Vascular Responses ◽  
Pressure Changes ◽  
Handgrip Contractions

The effects of changes in transmural pressure on brachial artery mean blood velocity (MBV) were examined in humans. Transmural pressure was altered by using a specially designed pressure tank that raised or lowered forearm pressure by 50 mmHg within 0.2 s. Brachial MBV was measured with Doppler directly above the site of forearm pressure change. Pressure changes were evoked during resting conditions and after a 5-s handgrip contraction at 25% maximal voluntary contraction. The handgrip protocol selected was sufficiently vigorous to limit flow and sufficiently brief to prevent autonomic engagement. Changes in transmural pressure evoked directionally similar changes in MBV within 2 s. This was followed by large and rapid adjustments [−2.14 ± 0.24 cm/s (vasoconstriction) during negative pressure and +2.14 ± 0.45 cm/s (vasodilatation) during positive pressure]. These adjustments served to return MBV to resting levels. This regulatory influence remained operative after 5-s static handgrip contractions. Of note, changes in transmural pressure were capable of altering the timing of the peak MBV response (5 ± 0, 2 ± 0, 6 ± 1 s ambient, negative, and positive pressure, respectively) as well as the speed of MBV adjustment (−2.03 ± 0.18, −2.48 ± 0.15, −0.84 ± 0.19 cm · s−1 · s−1ambient, negative, and positive pressure, respectively) after handgrip contractions. Vascular responses, seen with changes in transmural pressure, provide evidence that the myogenic response is normally operative in the limb circulation of humans.

Postural vascular response vs. sympathetic vasoconstriction in human skin during orthostasis

1995 ◽  
Vol 269 (1) ◽  
pp. H53-H61 ◽  
Author(s):  
H. Jepsen ◽  
P. Gaehtgens
Keyword(s):  
External Pressure ◽  
Transmural Pressure ◽  
The Body ◽  
Sympathetic Activation ◽  
Vascular Response ◽  
Relative Contribution ◽  
Sympathetic Vasoconstriction ◽  
Pressure Changes ◽  
Male Subjects ◽  
Nonadditive Interaction

Sympathetic activation and local vascular smooth muscle reactions to vessel distension contribute to the increase in vascular resistance in the skin during orthostasis. The relative contribution of these two mechanisms to the changes of skin blood flow along the body axis on standing was investigated in healthy male subjects by laser-Doppler (LD) fluxmetry. Compared with recumbency, LD flux (LDF) in the standing subjects was reduced by -19.6 +/- 7.2% at the forehead and by -69.6 +/- 9.6% in the leg. In the absence of hydrostatic pressure changes, the LDF changes on standing averaged -29 +/- 13%, independent of skin region, reflecting the effect of vasoconstriction due to sympathetic activation. The postural vascular response, elicited by lowering the arm or the leg from heart level, was significantly attenuated in orthostasis compared with recumbency. The vessel reaction to local alteration of transmural pressure was studied in the skin of the forehead and lower leg by application of external pressure in supine subjects. No difference in vessel responsiveness to changes of transmural pressure was found between these skin sites. The findings suggest that the changes of skin perfusion in orthostasis result from a nonadditive interaction of height-dependent and -independent mechanisms.

Introduction

2018 ◽  
Author(s):  
Nora Goldschmidt ◽  
Barbara Graziosi
Keyword(s):  
Material Culture ◽  
The Body ◽  
Specific Site ◽  
Entire Volume ◽  
The Third ◽  
Religious Significance ◽  
Classical Poetry ◽  
Life Of The Mind ◽  
The Mind ◽  
Made In

The Introduction sheds light on the reception of classical poetry by focusing on the materiality of the poets’ bodies and their tombs. It outlines four sets of issues, or commonplaces, that govern the organization of the entire volume. The first concerns the opposition between literature and material culture, the life of the mind vs the apprehensions of the body—which fails to acknowledge that poetry emerges from and is attended to by the mortal body. The second concerns the religious significance of the tomb and its location in a mythical landscape which is shaped, in part, by poetry. The third investigates the literary graveyard as a place where poets’ bodies and poetic corpora are collected. Finally, the alleged ‘tomb of Virgil’ provides a specific site where the major claims made in this volume can be most easily be tested.

scholarly journals Non-destructive handheld XRF study of archaeological composite silver objects—the case study of the late Roman Seuso Treasure

2021 ◽  
Vol 13 (5) ◽  
Author(s):  
Viktória Mozgai ◽  
Bernadett Bajnóczi ◽  
Zoltán May ◽  
Zsolt Mráv
Keyword(s):  
Fluorescence Analysis ◽  
The Body ◽  
High Quality ◽  
X Ray ◽  
Composite Objects ◽  
Mechanical Attachment ◽  
Non Destructive ◽  
Made In ◽  
Late Roman

AbstractThis study details the non-destructive chemical analysis of composite silver objects (ewers, situlas, amphora and casket) from one of the most significant late Roman finds, the Seuso Treasure. The Seuso Treasure consists of fourteen large silver vessels that were made in the fourth–early fifth centuries AD and used for dining during festive banquets and for washing and beautification. The measurements were systematically performed along a pre-designed grid at several points using handheld X-ray fluorescence analysis. The results demonstrate that all the objects were made from high-quality silver (above 90 wt% Ag), with the exception of the base of the Geometric Ewer B. Copper was added intentionally to improve the mechanical properties of soft silver. The gold and lead content of the objects shows constant values (less than 1 wt% Au and Pb). The chemical composition as well as the Bi/Pb ratio suggests that the parts of the composite objects were manufactured from different silver ingots. The ewers were constructed in two ways: (i) the base and the body were made separately, or (ii) the ewer was raised from a single silver sheet. The composite objects were assembled using three methods: (i) mechanical attachment; (ii) low-temperature, lead-tin soft solders; or (iii) high-temperature, copper-silver hard solders. Additionally, two types of gilding were revealed by the XRF analysis, one with remnants of mercury, i.e. fire-gilding, and another type without remnants of mercury, presumably diffusion bonding.

scholarly journals Air Movement in Snow Due to Windpumping

1989 ◽  
Vol 35 (120) ◽  
pp. 209-213 ◽  
Author(s):  
S.C. Colbeck
Keyword(s):  
Pore Space ◽  
Barometric Pressure ◽  
Surface Flows ◽  
Wind Speeds ◽  
Compression And Expansion ◽  
Strong Winds ◽  
Pressure Changes ◽  
Low Amplitude ◽  
Pressure Perturbations ◽  
Rapid Pressure

Abstract Strong winds can disrupt the thermal regime in seasonal snow because of the variation in surface pressure associated with surface features like dunes and ripples. Topographical features of shorter wavelengths produce stronger surface flows, but the flow decays rapidly with depth. Longer-wavelength features produce weaker surface flows but the flow decays more slowly with depth. The flow may only be strong enough to disrupt the temperature field for features of wavelengths on the scale of meters or tens of meters at wind speeds of 10 m/s or more. Other possible causes of windpumping have been examined but they do not appear to be as significant. Rapid pressure perturbations due to turbulence produce very little displacement of the air because of the high frequency and low amplitude. Barometric pressure changes cause compression and expansion of the air in the pore space, but the rate is too low to have much effect.

Some Experiments on the Extra-Corporeal Hatching of the Eggs of Ascaris suum

1939 ◽  
Vol 17 (2) ◽  
pp. 69-82 ◽  
Author(s):  
D. W. Fenwick
Keyword(s):  
Hydrochloric Acid ◽  
Digestive Tract ◽  
Sodium Carbonate ◽  
Ascaris Suum ◽  
The Body ◽  
Very Old ◽  
The Past ◽  
Pancreatic Fluid ◽  
Sand Cultures ◽  
Made In

Numerous attempts have been made in the past to induce the eggs of Ascaris suum to hatch outside the body of the host. Extra-corporeal hatching has been observed under a variety of conditions by different workers. Kondo (1920, 1922), Asada (1921) and others record hatching in water, charcoal and sand cultures. Wharton (1915) states that hatching will occur in alkaline digestive juices, while Martin (1913) records a similar phenomenon in pancreatic fluid. Many different explanations have been offered to explain this hatching. Wharton suggested that the interaction of algae and sand might have some effect. Ohba (1923), who found that hatching would occur in 0·2% hydrochloric acid and 0·2% sodium carbonate believed that extra-corporeal hatching was limited to very old cultures of eggs. Many workers are of the opinion that some stimulus normally present in the digestive tract is necessary for hatching.

Study of Toynbee Phenomenon by Combined Intranasopharyngeal and Tympanometric Measurements

1988 ◽  
Vol 97 (2) ◽  
pp. 199-206 ◽  
Author(s):  
Yehuda Finkelstein ◽  
Yuval Zohar ◽  
Yoav P. Talmi ◽  
Nelu Laurian
Keyword(s):  
Middle Ear ◽  
Negative Pressure ◽  
Pressure Change ◽  
Positive Pressure ◽  
New Information ◽  
Pressure Changes ◽  
Rapid Pressure

The Toynbee maneuver, swallowing when the nose is obstructed, leads in most cases to pressure changes in one or both middle ears, resulting in a sensation of fullness. Since first described, many varying and contradictory comments have been reported in the literature concerning the type and amount of pressure changes both in the nasopharynx and in the middle ear. In our study, the pressure changes were determined by catheters placed into the nasopharynx and repeated tympanometric measurements. New information concerning the rapid pressure variations in the nasopharynx and middle ear during deglutition with an obstructed nose was obtained. Typical individual nasopharyngeal pressure change patterns were recorded, ranging from a maximal positive pressure of + 450 to a negative pressure as low as −320 mm H2O.

The relevance of therapeutic drug monitoring in plasma and erythrocytes in anti-cancer drug treatment

2004 ◽  
Vol 42 (11) ◽  
Author(s):  
Herlinde Dumez ◽  
Gunther Guetens ◽  
Gert De Boeck ◽  
Martin S. Highley ◽  
Robert A. A. Maes ◽  
...  
Keyword(s):  
Therapeutic Drug Monitoring ◽  
Drug Monitoring ◽  
Drug Transport ◽  
Free Fraction ◽  
The Body ◽  
Cancer Drug ◽  
Therapeutic Drug ◽  
Anti Cancer ◽  
Plasma Compartment ◽  
Made In

AbstractTherapeutic drug monitoring generally focuses on the plasma compartment only. Differentiation between the total plasma concentration and the free fraction (plasma water) has been described for a number of limited drugs. Besides the plasma compartment, blood has also a cellular fraction which has by far the largest theoretical surface and volume for drug transport. It is with anti-cancer drugs that major progress has been made in the study of partition between the largest cellular blood compartment, i.e., erythrocytes, and the plasma compartment. The aim of the present review is to detail the progress made in predicting what a drug does in the body, i.e., pharmacodynamics including toxicity and plasma and/or red blood cell concentration monitoring. Furthermore, techniques generally used in anti-cancer drug monitoring are highlighted. Data for complex Bayesian statistical approaches and population kinetics studies are beyond the scope of this review, since this is generally limited to the plasma compartment only.

Changes in Blood Pressure, Heart Rate and Breathing Rate During Moderate Swimming Activity in Rainbow Trout

1967 ◽  
Vol 46 (2) ◽  
pp. 307-315 ◽  
Author(s):  
E. DON STEVENS ◽  
D. J. RANDALL
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Rainbow Trout ◽  
Venous Blood ◽  
The Body ◽  
Swimming Activity ◽  
Breathing Rate ◽  
Blood Pressures ◽  
Ventral Aorta ◽  
Pressure Changes

1. Changes in blood pressure in the dorsal aorta, ventral aorta and subintestinal vein, as well as changes in heart rate and breathing rate during moderate swimming activity in the rainbow trout are reported. 2. Blood pressures both afferent and efferent to the gills increased during swimming and then returned to normal levels within 30 min. after exercise. 3. Venous blood pressure was characterized by periodic increases during swimming. The pressure changes were not in phase with the body movements. 4. Although total venous return to the heart increased during swimming, a decreased blood flow was recorded in the subintestinal vein. 5. Heart rate and breathing rate increased during swimming and then decreased when swimming ceased. 6. Some possible mechanisms regulating heart and breathing rates are discussed.

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