Lymphatic regulation of hematocrit during hypoxia in the toad Bufo woodhousei

1995 ◽  
Vol 269 (4) ◽  
pp. R814-R821 ◽  
Author(s):  
G. M. Malvin ◽  
S. Macias ◽  
M. Sanchez ◽  
R. Dasalla ◽  
A. Park ◽  
...  
Keyword(s):  
Plasma Volume ◽  
Lymph Flow ◽  
Cholinergic Nerves ◽  
Arterial Blood ◽  
Rate Of Increase ◽  
Lymph Heart ◽  
Flow Through ◽  
Bufo Woodhousei ◽  
Induced Changes ◽  
Toad Bufo

Hypoxia rapidly increases hematocrit (Hct) in anuran amphibians by reducing plasma volume, but the mechanism(s) mediating this response is unknown. We tested the hypothesis that, during hypoxia, plasma volume is reduced by impaired lymph heart (LH) function, decreasing lymph flow into the circulation. In Bufo woodhousei, we measured the effects of hypoxia on Hct, lymph heart rate (LHR), LH pressure, the movement of dye from the dorsal lymph sac to the arterial blood, and flow through an open LH cannula. We also tested whether splenic contraction or cholinergic nerves contribute to the hypoxia-induced changes. Graded hypoxia between 21 and 4% O2 produced graded increases in Hct (P < 0.0001) and decreases in LHR (P = 0.01). Hypoxia reduced the rate of increase in arterial Evans blue concentration after injection into the dorsal lymph sac (P = 0.041) and decreased flow through an open LH cannula (P < 0.012). Hypoxia increased Hct and reduced LHR similarly in control, splenectomized, and sham-splenectomized toads. Atropine had no significant effect on Hct and LHR. These results indicate that the LHs play a regulatory role in hypoxia-induced hemoconcentration.

Regulation of Blood Flow through Ventral Pelvic Skin by Environmental Water and NaCl in the Toad Bufo woodhousei

1992 ◽  
Vol 65 (3) ◽  
pp. 540-553 ◽  
Author(s):  
Gary M. Malvin ◽  
Laura Hood ◽  
Marlene Sanchez
Keyword(s):  
Blood Flow ◽  
Environmental Water ◽  
Flow Through ◽  
Bufo Woodhousei ◽  
Toad Bufo

scholarly journals Posterior lymph heart pressure and rate and lymph flow in the toad Bufo marinus in response to hydrated and dehydrated conditions

1992 ◽  
Vol 169 (1) ◽  
pp. 207-220 ◽  
Author(s):  
J. M. Jones ◽  
L. A. Wentzell ◽  
D. P. Toews
Keyword(s):  
Heart Rate ◽  
Systolic Pressure ◽  
Lymph Flow ◽  
Bufo Marinus ◽  
Lymph Drainage ◽  
Constant Measurement ◽  
Lymph Heart ◽  
The Mean ◽  
Toad Bufo ◽  
New Surgical Technique

Posterior lymph heart pressure, rate and flow were measured in chronically cannulated Bufo marinus during normal hydrated and dehydrated conditions. A new surgical technique was developed which allowed direct and constant measurement of the functioning of the posterior lymph hearts with minimal disruption to normal lymph drainage. The mean intra-lymph-heart systolic pressure was 2.29 +/− 0.12 kPa for hydrated animals at rest, decreasing to 1.01 +/− 0.10 kPa after 24 h of dehydration. Similarly, lymph heart rate, which was 48.2 +/− 1.7 beats min-1 under hydrated conditions, decreased to 31.8 +/− 4.6 beats min-1 after 18 h of dehydration. Lymph flow decreased almost to zero during dehydration from a hydrated rate of 1.11 +/− 0.04 ml h-1 100 g-1. This is the first study to measure directly and to correlate these variables in an amphibian and to show specifically that pressure, rate and lymph flow are significantly reduced during periods of dehydration.

scholarly journals Mathematical study on two-fluid model for flow of K–L fluid in a stenosed artery with porous wall

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
R. Ponalagusamy ◽  
Ramakrishna Manchi
Keyword(s):  
Theoretical Study ◽  
Fluid Model ◽  
Porous Wall ◽  
Governing Equations ◽  
Rate Of Increase ◽  
Special Cases ◽  
Stenosed Artery ◽  
Flow Through ◽  
Two Fluid Model ◽  
Two Fluid

AbstractThe present communication presents a theoretical study of blood flow through a stenotic artery with a porous wall comprising Brinkman and Darcy layers. The governing equations describing the flow subjected to the boundary conditions have been solved analytically under the low Reynolds number and mild stenosis assumptions. Some special cases of the problem are also presented mathematically. The significant effects of the rheology of blood and porous wall of the artery on physiological flow quantities have been investigated. The results reveal that the wall shear stress at the stenotic throat increases dramatically for the thinner porous wall (i.e. smaller values of the Brinkman and Darcy regions) and the rate of increase is found to be 18.46% while it decreases for the thicker porous wall (i.e. higher values of the Brinkman and Darcy regions) and the rate of decrease is found to be 10.21%. Further, the streamline pattern in the stenotic region has been plotted and discussed.

Observations on Body Temperature and Activity in the Toad Bufo woodhousei fowleri

Copeia ◽  
1966 ◽  
Vol 1966 (3) ◽  
pp. 581 ◽  
Author(s):  
Sydney Hadfield
Keyword(s):  
Body Temperature ◽  
Bufo Woodhousei ◽  
Toad Bufo

Direct measurement of flow from the posterior lymph hearts of hydrated and dehydrated toads (Bufo marinus).

1997 ◽  
Vol 200 (11) ◽  
pp. 1695-1702 ◽  
Author(s):  
J M Jones ◽  
A K Gamperl ◽  
A P Farrell ◽  
D P Toews
Keyword(s):  
Heart Rate ◽  
Stroke Volume ◽  
Systolic Pressure ◽  
Lymph Flow ◽  
Bufo Marinus ◽  
Experimental Chamber ◽  
Doppler Flow ◽  
Simultaneous Measurements ◽  
Pressure Development ◽  
Lymph Heart

Flow from the posterior lymph hearts of Bufo marinus was measured using Doppler flow probes. These probes were placed on the posterior vertebral vein and recorded flow as lymph was ejected from the heart. In resting, hydrated toads, mean lymph flow from one of the paired posterior lymph hearts was 25.9 +/- 4.9 ml kg-1 h-1, stroke volume was 8.9 +/- 1.4 microL kg-1 and lymph heart rate was 47.5 +/- 3.7 beats min-1. We estimate that, together, the paired posterior lymph hearts are capable of generating flows that are approximately one-sixtieth of the resting cardiac output. Mean peak systolic pressure developed by the posterior lymph hearts was 1.62 +/- 0.08 kPa. Simultaneous measurements of lymph heart pressure development and flow revealed that the outflow pore of the heart opened at a pressure of 0.71 +/- 0.04 kPa, approximately 113 +/- 5 ms into systole. When toads were moderately disturbed, stroke volume increased by as much as fourfold with little change in lymph heart rate (&lt; 5 beats min-1). When toads were dehydrated, lymph flow decreased by 70% at 12h and by 80% and 24h. Since there was only a modest non-significant decrease in lymph heart rate (30%), this reduction in flow was attributed to decreases in stroke volume (approximately 80%). Lymph heart flow and stroke volume returned to control values 30 min after adding water back into the experimental chamber. Stroke volume was clearly more important in regulating lymph flow than lymph heart rate under these conditions in Bufo marinus.

Modification of bronchial blood flow during allergic airway responses

1988 ◽  
Vol 65 (1) ◽  
pp. 272-282 ◽  
Author(s):  
W. M. Long ◽  
L. D. Yerger ◽  
H. Martinez ◽  
E. Codias ◽  
C. L. Sprung ◽  
...  
Keyword(s):  
Blood Flow ◽  
Specific Antigen ◽  
Mast Cell Degranulation ◽  
Arterial Blood Flow ◽  
Antigen Challenge ◽  
Vascular Response ◽  
Pulmonary Hemodynamics ◽  
Arterial Blood ◽  
Airway Responses ◽  
Induced Changes

Ascaris suum antigen effects on mean airflow resistance (RL) and bronchial arterial blood flow (Qbr) were studied in allergic anesthetized sheep with documented airway responses. Qbr was measured with electromagnetic flow probes, and supplemental O2 prevented antigen-induced hypoxemia. Aerosol challenge with this specific antigen increased RL and Qbr significantly. Cromolyn sodium aerosol pretreatment prevented antigen-induced increases in RL but not in Qbr. Intravenous cromolyn, however, prevented increases in Qbr and RL, suggesting a role for mast cell degranulation in both bronchomotor and bronchovascular responses to antigen. Antigen-induced increases in Qbr were not solely attributable to histamine release. Indomethacin pretreatment attenuated the antigen-induced increase in Qbr, thus suggesting that vasodilator cyclooxygenase products contribute to the vascular response. Antigen challenge significantly decreased Qbr after indomethacin and metiamide pretreatment, which suggests that vasoconstrictor substances released after antigen exposure also modulate Qbr; however, released vasodilators overshadow vasoconstrictor effects. Thus antigen challenge affects Qbr by locally releasing histamine and vasodilator prostaglandins as well as vasoconstrictor substances. These effects were independent of antigen-induced changes in systemic and pulmonary hemodynamics.

Pregnancy-induced changes in the maximal physiological responses during swimming

1991 ◽  
Vol 71 (4) ◽  
pp. 1454-1459 ◽  
Author(s):  
R. G. McMurray ◽  
A. C. Hackney ◽  
V. L. Katz ◽  
M. Gall ◽  
W. J. Watson
Keyword(s):  
Pregnant Women ◽  
Plasma Volume ◽  
Physiological Responses ◽  
Cycle Ergometry ◽  
O2 Uptake ◽  
Heart Rates ◽  
Capillary Dynamics ◽  
Exercise Induced ◽  
Induced Changes

The effect of pregnancy on peak O2 uptake (VO2 peak) during tethered swimming was evaluated in 10 women during their 25th and 35th wk of pregnancy, as well as 9–11 wk postpartum. The swim results were compared with cycle ergometry results obtained at similar times. The results indicated that exercise-induced maximal heart rates remained the same and were similar for the swim and cycle trials, approximately 184 +/- 4 beats/min. Cycling VO2 peak was not affected by pregnancy, averaging 1.94 +/- 0.11 l/min. Postpartum swim VO2 peak was similar to the cycle results; however, during pregnancy it was significantly lower than cycling VO2 peak (P less than 0.05; postpartum, 1.78 +/- 0.14 l/min; 25th wk, 1.64 +/- 0.12; 35th wk, 1.48 +/- 0.11). Hemoglobin concentrations and hematocrits were lower during pregnancy; however, changes in plasma volume (based on hematocrit and hemoglobin) were found to be significantly greater during cycling than during swimming and also greater during pregnancy for both modes of exercise. It was concluded that, unlike cycling, the VO2 peak of pregnant women during swimming is reduced. This reduction in VO2 peak was associated with a decreased peak ventilation (r = 0.864) but was not correlated to exercise-induced hemoconcentration (r = -0.29). Furthermore, pregnancy results in a greater-than-normal exercise-induced hemoconcentration, which may be related to pregnancy-induced changes in capillary dynamics.

scholarly journals Estimation of Pressure Drop Required for Lymph Flow through Initial Collecting Lymphatics

2015 ◽  
Vol 29 (S1) ◽  
Author(s):  
Scott Stewart ◽  
David Sloas ◽  
Walter Murfee
Keyword(s):  
Pressure Drop ◽  
Lymph Flow ◽  
Flow Through
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