Interstitial and intravascular pressures in conscious dogs during head-out water immersion

Water immersion (WI) causes an increase in plasma volume in humans and dogs. To determine the mechanism for this fluid movement, the transmission of external water hydrostatic pressure to the interstitial and vascular compartments was studied in six conscious dogs. Systemic arterial, central venous, peripheral arterial (ulnar artery) and venous (cephalic vein), pleural, intra-abdominal, and interstitial fluid hydrostatic (by Guyton's capsule and wick catheter method) pressures and external reference water pressure were measured at three different levels of WI: 1) extremities only, 2) midchest, and 3) midcervical levels at 37 degrees C. There was a significant linear relationship between interstitial fluid hydrostatic pressure (X) and external water pressure (Y): (Y = 0.86X + 1.4, r = 0.93 by Guyton's capsule; Y = 0.85X + 2.4, r = 0.93 by wick catheter. However, vascular pressures did not change when dogs were immersed at the level of the extremities. These pressures increased only during WI at the midchest and midcervical levels. Therefore the pressure gradient that develops between the interstitial and intravascular compartments is probably the major reason for the transcapillary fluid shift during WI.

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Extracellular fluid and plasma volumes during water immersion in nephrectomized dogs

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1987.252.5.r972 ◽

1987 ◽

Vol 252 (5) ◽

pp. R972-R978 ◽

Cited By ~ 1

Author(s):

K. Miki ◽

G. Hajduczok ◽

S. K. Hong ◽

J. A. Krasney

Keyword(s):

Hydrostatic Pressure ◽

Plasma Volume ◽

Water Pressure ◽

Water Immersion ◽

Control Level ◽

Extracellular Fluid ◽

Intracellular Space ◽

External Water Pressure ◽

External Water ◽

Kinetics Of

Extracellular fluid volume (ECF, [125I]iothalamate space), blood volume (BV, 51Cr-labeled erythrocyte space), and hematocrit were measured continuously to study the kinetics of fluid movements between intracellular, interstitial, and plasma compartments during water immersion (WI) at 38 degrees C in seven splenectomized and acutely nephrectomized dogs. ECF and plasma volume (PV) increased linearly during WI by 10 +/- 2 ml/kg (4% of initial ECF volume, P less than 0.05) and 12 +/- 2 ml/kg (33% of initial PV, P less than 0.05), respectively, above the control level by 120 min of WI. We estimate that 83% of the fluid entering the intravascular compartment is derived from the intracellular space at 120 min of WI. The results of this study indicate that WI leads to a sustained fluid movement of intracellular fluid toward the intravascular compartment. The increase in interstitial hydrostatic pressure (wick method) by 28.5 mmHg from the control level at 5 min of WI in response to the external water pressure exceeds the increase in mean capillary pressure by 10-11 mmHg relative to the control level. We postulate that this negative hydrostatic pressure gradient across the capillary wall leads to an increase in PV during WI.

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The role of mural mechanics on cephalopod palaeoecology

Journal of The Royal Society Interface ◽

10.1098/rsif.2020.0009 ◽

2020 ◽

Vol 17 (164) ◽

pp. 20200009 ◽

Cited By ~ 1

Author(s):

Robert Lemanis ◽

Deborah Stier ◽

Igor Zlotnikov ◽

Paul Zaslansky ◽

Dirk Fuchs

Keyword(s):

Hydrostatic Pressure ◽

Water Pressure ◽

Attachment Site ◽

Peak Stress ◽

Structural Function ◽

Prismatic Layer ◽

Functional Interpretation ◽

Hard Limit ◽

External Water Pressure ◽

External Water

Cephalopods transformed the molluscan shell into a buoyancy device that must be strong enough to resist external water pressure. Historically, unique features of the shell have been interpreted on the basis that the strength of the shell presents a hard limit on maximum habitat depth. One such feature is the mural flap, which is a semi-prismatic layer deposited on the inner surface of some coleoid septa that has been suggested to strengthen the shell and permit colonization of deeper waters. We test this hypothesis by constructing finite-element models that show how mural modifications affect the response of the shell to hydrostatic pressure. The mural flaps are found to have no notable structural function. Another mural modification discovered here is the adapical ridge flap that initially seemed to have a potential function in shifting peak stress away from the attachment site of the septum; however, the irregular distribution of this feature casts any functional interpretation in doubt. Ecological separation of belemnites and decabrachians is likely not mediated by the presence/absence of mural flaps. This work illustrates a potential caveat that not all unique septal features formed in response to increasing hydrostatic pressure and deeper habitats.

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Fluid shifts and endocrine responses during chair rest and water immersion in man

Journal of Applied Physiology ◽

10.1152/jappl.1980.48.1.79 ◽

1980 ◽

Vol 48 (1) ◽

pp. 79-88 ◽

Cited By ~ 26

Author(s):

J. E. Greenleaf ◽

E. Shvartz ◽

S. Kravik ◽

I. C. Keil

Keyword(s):

Plasma Volume ◽

Body Position ◽

Water Pressure ◽

Water Immersion ◽

Extracellular Volume ◽

Urine Volume ◽

Plasma Osmolality ◽

Positive Balance ◽

External Water Pressure ◽

External Water

To determine the effect of external water pressure per se on intercompartmental fluid volume shifts, plasma and urine electrolytes, osmotic and endocrine responses were compared in four men (21-22 yr) during 8 h of water immersion (TH2O = 34.4 degrees C) and during 8 h of chair rest (Ta = 22.5 degrees C), followed by16 h of bed rest in both regimens. Water intake was 1,800 ml during 8-h exposures. Urine volume during immersion was 2,954 ml/8 h and 1,538 ml/8 h (P less than 0.01) during chair rest; the respective decreases in extracellular volume (ECV) were 2,230 ml/8 h and 1,892 ml/8 h. Losses from the intersititial volume (1.81 vs. 1.67 liters) and plasma volume (0.43 vs. 0.23 liters) during immersion and chair rest, respectively, were approximately proportional to theri normal ratios. With a negative H2O balance (corrected for blood withdrawal) during immersion of 1,234 ml and a positive balance (190 ml) during chair rest, there appeared to be a shift of ECV to the intracellular compartment in both regimens. There was suppression of both plasma arginine vasopressin (AVP) and renin activity (PRA) during chair rest and immersion. It appears that the increased central blood volume, as opposed to increased plasma osmolality, is the primary stimulus for AVP suppression.In hyperhydrated subjects, about half (6.7%) of the immersion plasma volume loss of 12.6% could be attributed to orthostatic responses associated with the upright body position during chair rest and the remaining half to the external water pressure.

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Analysis of Tunnel Water Inrush Considering the Influence of Surrounding Rock Permeability Coefficient by Excavation Disturbance and Ground Stress

Applied Sciences ◽

10.3390/app11083645 ◽

2021 ◽

Vol 11 (8) ◽

pp. 3645

Author(s):

Helin Fu ◽

Pengtao An ◽

Long Chen ◽

Guowen Cheng ◽

Jie Li ◽

...

Keyword(s):

Permeability Coefficient ◽

Water Pressure ◽

Water Inrush ◽

Surrounding Rock ◽

Water Inflow ◽

Calculation Error ◽

External Water Pressure ◽

Ground Stress ◽

External Water ◽

Inflow Prediction

Affected by the coupling of excavation disturbance and ground stress, the heterogeneity of surrounding rock is very common. Presently, treating the permeability coefficient as a fixed value will reduce the prediction accuracy of the water inflow and the external water pressure of the structure, leading to distortion of the prediction results. Aiming at this problem, this paper calculates and analyzes tunnel water inflow when considering the heterogeneity of permeability coefficient of surrounding rock using a theoretical analysis method, and compares with field data, and verifies the rationality of the formula. The research shows that, when the influence of excavation disturbance and ground stress on the permeability coefficient of surrounding rock is ignored, the calculated value of the external water force of the tunnel structure is too small, and the durability and stability of the tunnel are reduced, which is detrimental to the safety of the structure. Considering the heterogeneity of surrounding rock, the calculation error of water inflow can be reduced from 27.3% to 13.2%, which improves the accuracy of water inflow prediction to a certain extent.

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Control of arterial pressure in aquatic sea snakes

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1983.244.1.r66 ◽

1983 ◽

Vol 244 (1) ◽

pp. R66-R73 ◽

Cited By ~ 3

Author(s):

H. B. Lillywhite ◽

F. H. Pough

Keyword(s):

Arterial Pressure ◽

Blood Volume ◽

Water Pressure ◽

Cardiovascular Responses ◽

Physiological Regulation ◽

Sea Snakes ◽

Head Up Tilt ◽

External Water Pressure ◽

External Water ◽

Head Level

Cardiovascular responses to head-up tilt, acutely graded hemorrhage, and pharmacologic stimulation by principal autonomic drugs were studied in four species of marine snakes, principally Aipysurus laevis (family Hydrophiidae). Arterial pressure varied inversely with tilt angle and blood volume deficit in conscious snakes outside of water, indicating that physiological regulation was poor or lacking. Calculated arterial pressures at head level typically diminished to zero in A. laevis tilted to angles greater than or equal to 30 degrees. Arterial pressure (corrected for external water pressure) did not change when these snakes were tilted in seawater. Changes of arterial pressure induced by tilt, blood loss, or autonomic drugs elicited reflex adjustments in heart activity, but the magnitude of these responses was less than that observed in terrestrial species of snake. It is concluded that baroreflexes are present but comparatively ineffective in sea snakes. Snakes tolerated large losses of blood volume, and extravascular fluids were absorbed into the circulation during hemorrhage; both hemorrhage and estimated hemodilution volumes exceeded 100% of the initial blood volume in Acalyptophis peronii. Thus, in marine snakes major fluid shifts between nonvascular and vascular compartments significantly compensate hypovolemia but, because of minor autonomic adjustments, do not result in a well-regulated arterial pressure.

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A multicentered comparison of measurements obtained with microtip and external water pressure transducers

International Urogynecology Journal ◽

10.1007/s00192-005-0027-0 ◽

2005 ◽

Vol 17 (4) ◽

pp. 400-406 ◽

Cited By ~ 12

Author(s):

Andrew F. Hundley ◽

Morton B. Brown ◽

Linda Brubaker ◽

Geoffrey W. Cundiff ◽

Karl Kreder ◽

...

Keyword(s):

Water Pressure ◽

Pressure Transducers ◽

External Water Pressure ◽

External Water

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Instruments and Methods High Pressure Coupling for Pipe in Deep Water Filled Bore Holes

Journal of Glaciology ◽

10.3189/s0022143000028380 ◽

1963 ◽

Vol 4 (36) ◽

pp. 809-812

Author(s):

R. L. Shreve

Keyword(s):

High Pressure ◽

Water Pressure ◽

The Other ◽

Internal Diameter ◽

External Diameter ◽

Synthetic Rubber ◽

External Water Pressure ◽

External Water ◽

One Year ◽

Aluminum Pipe

AbstractIn August 1961 an aluminum pipe (3.5 cm. internal diameter, 4.2 cm. external diameter) having 92 specially modified socket couplings (5.0 cm. external diameter) sealed with a quick-polymerizing synthetic rubber was sunk 226 m. in a vertical water-filled bore hole in Blue Glacier, Washington. U.S.A. The geometry of threads and mating surfaces of pipe and coupling was designed to cause increasing external water pressure to tighten the seal. One joint at a depth of 66 m. immediately developed an extremely slow leak (probably because of faulty cleaning), but the other 91 joints apparently were sound, as the pipe was free of water to a depth of at least 157 m. when resurveyed after one year.

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