PGE1-induced intestinal secretion: mechanism of enhanced transmucosal protein efflux.

The effects of local intra-arterial prostaglandin E1 (PGE1) infusion on net transmucosal volume and protein fluxes, lymphatic volume and protein fluxes, and regional hemodynamics were ascertained in autoperfused segments of cat ileum. After acquiring control values (and tissue samples) for the various parameters, PGE1 (5.0 microgram/min) was infused directly into the superior mesenteric artery. The PGE1 infusions resulted in dramatic increases in ileal lymphatic volume and protein fluxes and blood flow. Infusion of PGE1 caused a reversion of net mucosal volume absorption to net secretion and an increased loss of plasma proteins into the lumen. Ultrastructural analysis of tissue samples taken during the PGE1 infusion indicate major structural damage to the mucosal membrane. The physiological and ultrastructural data acquired in this study suggest that 1) the increased transmucosal protein efflux during intra-arterial PGE1 infusions results from an alteration in mucosal transcapillary fluid exchange and 2) a significant portion of PGE1-induced ileal secretion is passively mediated.

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Mechanism of glucagon-induced intestinal secretion

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1980.239.1.g30 ◽

1980 ◽

Vol 239 (1) ◽

pp. G30-G38

Author(s):

D. N. Granger ◽

P. R. Kvietys ◽

W. H. Wilborn ◽

N. A. Mortillaro ◽

A. E. Taylor

Keyword(s):

Capillary Pressure ◽

Plasma Proteins ◽

Fluid Pressure ◽

Intestinal Secretion ◽

Tissue Samples ◽

Mucosal Membrane ◽

Osmotic Reflection Coefficient ◽

Capillary Fluid ◽

Higher Doses ◽

Flow Capillary

The effects of local intra-arterial glucagon infusion on transcapilary, lymphatic, and transmucosal fluid and protein fluxes were studied in autoperfused segments of cat ileum. The glucagon infusions resulted in a significant increase in intestinal blood flow, lymph flow, capillary filtration coefficient, capillary pressure, interstitial volume, and interstitial fluid pressure. Precapillary resistance and the pre-to-postcapillary resistance ratio decreased during the glucagon infusion. The transcapillary oncotic pressure gradient and the osmotic reflection coefficient were reduced, suggesting that capillary permeability is significantly increased with glucagon. Ultrastructural analysis of tissue samples acquired during the infusion of higher doses of glucagon indicates disruption of the mucosal membrane. An glucagon indicates disruption of the mucosal membrane. An alteration in mucosal structure is supported by the appearance of plasma proteins in the secreted fluid. The results of this study indicate that glucagon-induced intestinal secretion results from an alteration in capillary fluid balance, i.e., an increased capillary pressure and permeability.

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Blood flow and high-energy phosphates in microregions of left ventricular subendocardium

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1981.240.5.h804 ◽

1981 ◽

Vol 240 (5) ◽

pp. H804-H810 ◽

Cited By ~ 1

Author(s):

H. D. Kleinert ◽

H. R. Weiss

Keyword(s):

Blood Flow ◽

Linear Relationship ◽

Tissue Perfusion ◽

High Energy ◽

Left Ventricular ◽

Significant Loss ◽

Tissue Blood Flow ◽

High Energy Phosphates ◽

Tissue Samples ◽

Heterogeneous Distribution

Blood flow and high-energy phosphate (HEP) content were determined simultaneously in multiple microregions of left ventricular subendocardium in 29 normal anesthetized open-chest rabbits by use of a new micromethod to determine whether a direct linear relationship existed between these parameters. Tissue samples weighed 1-2 mg. ATP and creatine phosphate (CP) content were quantitated in quick-frozen hearts by fluorometry at sites where tissue perfusion was measured by H2 clearance by use of bare-tipped platinum electrodes. A series of validation studies were conducted to ensure that 1) no significant damage to the tissue surrounding the electrode occurred during the period of experimentation and 2) no significant loss of biochemical constituents had occurred due to labile processes during freezing or storage of the tissue. Blood flow, ATP, and CP values averaged 79.1 +/- 24.1 (SD) ml.min-1.100 g-1, 4.9 +/- 1.3 mumol/g tissue, and 8.0 +/- 3.0 mumol/g tissue, respectively, and are similar to those reported in studies using larger tissue samples. Correlation between the heterogeneous distribution of tissue perfusion and HEP revealed no direct linear relationship between these parameters in the normal unstressed rabbit subendocardium.

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