Macromolecule permeability of in situ and excised rodent skeletal muscle arterioles and venules

Abstract

In microvessels, acute inflammation is typified by an increase in leukocyte-endothelial cell interactions, culminating in leukocyte transmigration into the tissue, and increased permeability to water and solutes, resulting in tissue edema. The goal of this study was to establish a method to quantify solute permeability (P(s)) changes in microvessels in intact predominantly blood-perfused networks in which leukocyte transmigratory behavior could be precisely described using established paradigms. We used intravital confocal microscopy to measure solute (BSA) flux across microvessel walls, hence P(s). A quantitative fluorescence approach (Huxley VH, Curry FE, and Adamson RH. Am J Physiol Heart Circ Physiol 252: H188-H197, 1987) was adapted to the imaged confocal tissue slice in which the fluorescent source volume and source surface area of the microvessel were restricted to the region of vessel that was contained within the imaged confocal tissue section. P(s) measurements were made in intact cremaster muscle microvasculature of anesthetized mice and compared with measurements of P(s) made in isolated rat skeletal muscle microvessels. Mouse arteriolar P(s) was 9.9 +/- 1.1 x 10(-7) cm/s (n = 16), which was not different from 8.4 +/- 1.3 x 10(-7) cm/s (n = 6) in rat arterioles. Values in venules were significantly (P < 0.05) higher: 44.4 +/- 7.9 x 10(-7) cm/s (n = 14) in mice and 25.0 +/- 3.7 x 10(-7) cm/s in rats. Convective coupling was estimated to contribute <10% to the measured P(s) in both microvessel types and both animal models. We conclude that this approach provides an appropriate quantification of P(s) in the intact microvasculature and that arteriolar P(s), while lower than in venules, is nevertheless consistent with arterioles being a significant source of interstitial protein.

KRIT1 Protein Depletion Modifies Endothelial Cell Behavior via Increased Vascular Endothelial Growth Factor (VEGF) Signaling

“…Preparation and visualization of the cremaster muscle as well as measurement of permeability to Alexa-488 BSA (Invitrogen) was performed as previously described (15,23). The vascular wall P s (cm/s) is calculated from the measured flux of fluorescent label across the vessel wall over time normalized to microvessel surface area at a known BSA concentration gradient (24).…”

TNF-α activation of arterioles and venules alters distribution and levels of ICAM-1 and affects leukocyte-endothelial cell interactions

“…The main arteriole was occluded by another micropipette upstream of the cannulation site at the time of the antibody loading to allow a complete perfusion of the downstream regions with the antibody solution. Intravascular pressure during perfusion with the antibody solutions is typically of the order of 20 cmH 2O in arterioles and 8 cmH 2O in venules (24), which is in the physiological range. After antibody labeling and reestablishment of blood perfusion, microvessel diameters are typically not different from diameters before the labeling protocol.…”

Adaptation of coronary microvascular exchange in arterioles and venules to exercise training and a role for sex in determining permeability responses

“…1). Preliminary work in this study, and detailed to a greater degree by studies of rat and mouse skeletal muscle preparations (53), suggests that the assumption of a circular cross section under the conditions of these experiments is valid for coronary arterioles. Venules, especially those in the coronary circulation, are less likely to have a circular cross section and instead are relatively flat such that the minor axis, b, is not equal to the measured major axis, D (31,58).…”

“…With a switch between the pairs of manometers, perfusate in the vessel could contain just nonfluorescent washout solution, be changed rapidly to the dye solution for a time necessary to measure solute flux, or to the clear washout to reestablish the baseline, all within seconds. The relatively low perfusion pressures (14.9 Ϯ 0.2 in arterioles and 10.3 Ϯ 0.4 cmH2O in venules) used in these experiments minimized the contributions of convective coupling, or solvent drag, in the estimates of apparent permeability (Ps) (26,53).…”