Sympathetic stimulation and intestinal capillary fluid exchange

Sympathetic nerve stimulation is generally considered not to alter intestinal capillary pressure or filtration rate because of appropriate adjustments in the pre-to-postcapillary resistance ratio. To directly assess this possibility, we measured lymph flow, capillary pressure, capillary filtration coefficient, and the transcapillary oncotic pressure gradient in the cat small intestine. Measurements were taken under control conditions and during the steady-state phase of periarterial nerve stimulation, i.e., following completion of the escape phase. Venous outflow pressure was held constant (0 mmHg) during the entire experiment. Nerve stimulation resulted in a significant reduction of lymph flow (by 65%), capillary filtration coefficient (by 75%), and capillary pressure (by 15%). Interstitial fluid pressure, calculated from the measured parameters in the Starling equation, was also reduced (from -0.74 to -2.53 mmHg) by nerve stimulation. The results of this study indicate that intestinal capillary pressure and capillary filtration rate are not "autoregulated" during sympathetic nerve stimulation. Capillary derecruitment appears to be largely responsible for the dramatic reduction in filtration rate associated with adrenergic stimulation.

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Autoregulation of intestinal capillary filtration rate

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1982.243.6.g475 ◽

1982 ◽

Vol 243 (6) ◽

pp. G475-G483

Author(s):

D. N. Granger ◽

N. A. Mortillaro ◽

M. A. Perry ◽

P. R. Kvietys

Keyword(s):

Arterial Pressure ◽

Capillary Pressure ◽

Filtration Rate ◽

Pressure Range ◽

Fluid Pressure ◽

Lymph Flow ◽

Filtration Coefficient ◽

Capillary Filtration ◽

Capillary Filtration Coefficient ◽

Flow Capillary

To determine whether intestinal capillary filtration rate, capillary pressure, or both are autoregulated in the cat ileum, the following parameters were measured under isovolumetric conditions: lymph flow, capillary pressure, capillary filtration coefficient, and lymph and plasma oncotic pressures. Superior mesenteric arterial pressure was reduced in 25-mmHg steps from 125 to 25 mmHg. As arterial pressure was reduced, lymph flow, capillary pressure, and the transcapillary oncotic pressure gradient decreased while the capillary filtration coefficient increased. Over the arterial pressure range of 75-125 mmHg, capillary pressure decreased in a fashion expected from a rigid system; however, capillary pressure was slightly autoregulated at lower arterial pressures. Lymph flow fell proportionately more than capillary pressure over the entire arterial pressure range. The results of this study indicate that intestinal capillary pressure and capillary filtration rate are poorly autoregulated in the cat when arterial pressure is reduced. Changes in interstitial fluid pressure play a major role in preventing interstitial dehydration in the cat ileum when arterial pressure is reduced.

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Evaluation of Starling forces in the equine digit

Journal of Applied Physiology ◽

10.1152/jappl.1988.64.4.1580 ◽

1988 ◽

Vol 64 (4) ◽

pp. 1580-1583 ◽

Cited By ~ 12

Author(s):

D. Allen ◽

R. J. Korthuis ◽

S. Clark

Keyword(s):

Capillary Pressure ◽

Interstitial Fluid ◽

Venous Pressure ◽

Fluid Pressure ◽

Calculated Data ◽

Filtration Coefficient ◽

Fluid Exchange ◽

Tissue Pressure ◽

Capillary Filtration ◽

Capillary Filtration Coefficient

A pump-perfused extracorporeal digital preparation was used to evaluate blood flow, arterial pressure, venous pressure, isogravimetric capillary filtration coefficient, capillary pressure, and vascular compliance in six normal horses. From these data, pre- and postcapillary resistances and pre- and postcapillary resistance ratios were determined. Vascular and tissue oncotic pressures were estimated from plasma and lymph protein concentrations, respectively. By use of the collected and calculated data, tissue pressure in the digit was calculated using the Starling equation. In the isolated equine digit, isogravimetric capillary pressure averaged 36.7 mmHg, plasma and lymph oncotic pressures averaged aged 19.12 and 6.6 mmHg, respectively, interstitial fluid pressure averaged 25.6 mmHg, and the capillary filtration coefficient averaged 0.0013 ml.min-1.mm-1.100 g-1. Our results indicate that digital capillary pressure in the laterally recumbent horse is much higher than in analogous tissues in other species such as dog and human. However, the potential edemagenic effects of this high digital capillary pressure are opposed by at least two mechanisms: 1) a high tissue pressure and 2) a low microvascular surface area for fluid exchange and/or a low microvascular permeability to filtered fluid.

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The effect of posture on the capillary filtration rate in the human forearm

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y70-063 ◽

1970 ◽

Vol 48 (6) ◽

pp. 405-414 ◽

Cited By ~ 3

Author(s):

P. D. Newberry ◽

J. M. McDonald ◽

E. R. Rowe

Keyword(s):

Filtration Rate ◽

Room Temperature ◽

Venous Pressure ◽

Filtration Coefficient ◽

Left Forearm ◽

Capillary Filtration ◽

Capillary Filtration Coefficient ◽

Human Forearm ◽

Capillary Resistance ◽

Male Subjects

A water-filled plethysmograph of a new design was used to measure the capillary filtration rate in the left forearm of each of six male subjects at a room temperature of 27 °C, in the supine and the seated positions. The adoption of the seated position resulted in a decrease of the capillary filtration rate by an average of 0.050 ± 0.015 S.E. ml/min∙100 ml (p < 0.02) and in an increase of the average threshold venous pressure for capillary filtration from 14 to 26 mm Hg (p < 0.01). This change was associated with an increase in the post-capillary resistance. Adoption of the seated position caused no significant change in the capillary filtration coefficient.

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Intestinal capillary filtration in experimental diabetes mellitus

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1987.253.1.g20 ◽

1987 ◽

Vol 253 (1) ◽

pp. G20-G25

Author(s):

R. J. Korthuis ◽

V. H. Pitts ◽

D. N. Granger

Keyword(s):

Diabetes Mellitus ◽

Reflection Coefficient ◽

Capillary Pressure ◽

Experimental Diabetes ◽

Lymph Flow ◽

Experimental Diabetes Mellitus ◽

Capillary Filtration ◽

Solute Exchange ◽

Capillary Filtration Coefficient ◽

Osmotic Reflection Coefficient

There is indirect evidence that indicates that intestinal transcapillary fluid and solute exchange is significantly altered in diabetes mellitus. To directly assess the dynamics of microvascular fluid and solute exchange in the small intestine (jejunum-ileum), we measured lymph flow, capillary pressure, capillary filtration coefficient, plasma and lymph oncotic pressures, and the osmotic reflection coefficient in anesthetized, fasted control rats and in rats in which diabetes was induced by a single injection of streptozotocin (65 mg/kg ip) 4 wk before the experiments. Diabetes was associated with an increase in lymph flow (by 120%), capillary pressure (by 34%), and capillary filtration coefficient (by 75%) when compared with values from control rats. The transcapillary oncotic pressure gradient was not altered by diabetes. Interstitial fluid pressure, calculated from the measured parameters in the Starling equation, was increased from -1.6 mmHg in control rats to +2.5 mmHg in diabetic animals. Analysis of lymph-to-plasma protein concentration ratios at various lymph flows suggests that the osmotic reflection coefficient in the diabetic intestine is comparable to that obtained in control animals. The results of this study indicate that experimental diabetes mellitus is associated with increases in intestinal capillary pressure and capillary filtration rate but that intestinal capillary permeability is not altered in this disorder.

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Hypothalamic and brachial nerve effects on circulation of isolated canine forelimb,

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1976.230.3.797 ◽

1976 ◽

Vol 230 (3) ◽

pp. 797-803 ◽

Cited By ~ 1

Author(s):

RP Menninger ◽

CH Baker

Keyword(s):

Electrical Stimulation ◽

Nerve Stimulation ◽

Constant Pressure ◽

Red Cells ◽

Filtration Coefficient ◽

Diffusion Capacity ◽

Capillary Filtration ◽

Capillary Filtration Coefficient ◽

Stimulation Of

Canine forelimbs were vascularly isolated and perfused at either constant inflow or constant inflow pressure. A comparison of the effects of electrical stimulation of hypothalamic pressor areas and brachial nerves was made on several vascular parameters. During constant pressure perfusion, forelimb resistance increased and total forelimb volume decreased. Additionally active vascular volumes measured with 131I-labeled albumin and 51Cr-labeled red cells decreased significantly. Capillary diffusion capacity product calculated from extraction of 86RbCl also decreased significantly as did the capillary filtration coefficient (CFC). The only significant differences between hypothalamic and brachial nerve stimulation were noted in the larger decreases in active volumes and CFC during the latter stimulations.

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Effect of histamine on microvasculature of isolated dog gracilis muscle

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1975.229.1.119 ◽

1975 ◽

Vol 229 (1) ◽

pp. 119-125 ◽

Cited By ~ 16

Author(s):

JE McNamee ◽

FS Grodins

Keyword(s):

Reflection Coefficient ◽

Capillary Pressure ◽

Plasma Protein ◽

Protein Concentration ◽

Gracilis Muscle ◽

Filtration Coefficient ◽

Plasma Protein Concentration ◽

Capillary Filtration ◽

Average Decrease ◽

Capillary Filtration Coefficient

Isogravimetric capillary pressure (Pci), capillary filtration coefficient (CFC), and plasma protein concentration were measured before and during adminisistration of histamine in an isolated, independently perfused canine gracilis muscle. Histamine produced an average decrease in Pci of 14.1 mmHg, an increase in CFC of 36-fold, and an increased rate of plasma protein escape of at least 24-fold. These results suggest that histamine reduces the reflection coefficient for protein at the capillary wall and are consistent with predictions of the theory of restricted diffusion assuming that 1-2.5% of available pores increase in radious from 40 to 240 A.

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PO2 modulation of paraquat-induced microvascular injury in isolated dog lungs

Journal of Applied Physiology ◽

10.1152/jappl.1990.68.5.2119 ◽

1990 ◽

Vol 68 (5) ◽

pp. 2119-2127 ◽

Cited By ~ 3

Author(s):

T. Shibamoto ◽

A. E. Taylor ◽

J. C. Parker

Keyword(s):

Latent Period ◽

Capillary Pressure ◽

Microvascular Permeability ◽

Filtration Coefficient ◽

Base Line ◽

Capillary Filtration ◽

Microvascular Injury ◽

Capillary Filtration Coefficient

We determined the effects of paraquat (PQ) concentrations ranging from 10(-3) to 10(-2) M and three levels of venous PO2 [hypoxia (41 +/- 3 Torr), normoxia (147 +/- 8 Torr), and hyperoxia (444 +/- 17 Torr)] in the presence of 4 x 10(-3) M PQ on microvascular permeability in isolated blood-perfused dog lungs. Capillary filtration coefficient (Kf,c) increased and isogravimetric capillary pressure (Pc,i) decreased 3 h after perfusion with 10(-2) M PQ (n = 7) and 5 h after perfusion with 4 x 10(-3) M PQ (n = 6) but not with 10(-3) M PQ (n = 4). In hyperoxic lungs perfused with 4 x 10(-3) M PQ, Kf,c increased to nine times the base-line value 5 h after PQ [0.15 +/- 0.01 to 1.35 +/- 0.25 (SE) ml.min-1.cmH2O-1.100 g-1]. Pc,i significantly decreased from a base-line value of 9.4 +/- 0.2 to 7.1 +/- 0.4 cmH2O at 3 h. In hypoxic lungs perfused with 4 x 10(-3) M PQ (n = 5), Pc,i and Kf,c changes were not significantly different from those in normoxic lungs treated with PQ. Thus both hyperoxia and an increased dose of PQ shortened the latent period and increased the severity of the PQ-induced microvascular permeability lesion, but hypoxia failed to prevent the PQ damage.

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Effects of histamine, serotonin, and norepinephrine on circulation of dog lungs

Journal of Applied Physiology ◽

10.1152/jappl.1984.57.1.223 ◽

1984 ◽

Vol 57 (1) ◽

pp. 223-232 ◽

Cited By ~ 35

Author(s):

B. Rippe ◽

R. C. Allison ◽

J. C. Parker ◽

A. E. Taylor

Keyword(s):

Capillary Pressure ◽

Vascular Resistance ◽

Capillary Permeability ◽

Constant Pressure ◽

Filtration Coefficient ◽

Constant Flow ◽

Flow Conditions ◽

Capillary Filtration ◽

Capillary Filtration Coefficient ◽

Lung Lobes

The action of histamine (H), serotonin (5-HT), and norepinephrine (NE) on the lung vasculature was evaluated in isolated blood-perfused dog lung lobes using isogravimetric techniques. Pre- and postcapillary resistances, isogravimetric capillary pressure (Pc,i), capillary filtration pressure (Pc,f), capillary filtration coefficient (Kf,c), and vascular pressure-volume relationships were measured. For constant-flow conditions, all drugs induced marked increases in both pre- and postcapillary resistances and increased Pc,f. The rise in Pc,f was most pronounced for H and least marked for NE and 5-HT. For constant-pressure perfusion, Pc,f increased slightly for H but not for NE and 5-HT, while total vascular resistance increased 4–5 times for all drugs. Vascular distensibility and volumes decreased markedly for NE and 5-HT but only slightly for H. None of the drugs appeared to alter capillary permeability because Kf,c and Pc,i measured during the infusions were not different from control.

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