Abstract
IntroductionRecent data suggested an interaction between plasma constituents and the endothelial glycocalyx to be relevant for vascular barrier function. This might be negatively influenced by infusion solutions, depending on ionic composition, pH and binding properties. The present study evaluated such an influence of current artificial preparations.MethodsIsolated guinea pig hearts were prepared in a modified Langendorff mode and perfused with Krebs-Henseleit buffer augmented with 1g% human albumin. After equilibration the perfusion was switched to replacement of one half buffer by either isotonic saline (NaCl), ringer's acetate (Ri-Ac), 6% and 10% hydroxyethyl starch (6% and 10% HES, resp.), or 4% gelatine (Gel), the artificial colloids having been prepared in balanced solution. We analysed glycocalyx shedding, functional integrity of the vascular barrier and heart performance.ResultsWhile glycocalyx shedding was not observed, diluting albumin concentration towards 0.5g% by artificial solutions was associated with a marked functional breakdown of vascular barrier competence. This effect was biggest with isotonic saline and significantly attenuated with artificial colloids, the difference in the pressure dependent transvascular fluid filtration (basal vs. during infusion in groups NaCl, Ri-Ac, 6% HES, 10% HES and Gel, n = 6 each) being 0.31 ± 0.03 vs. 1.00 ± 0.04; 0.27 ± 0.03 vs. 0.81 ± 0.03; 0.29 ± 0.03 vs. 0.68 ± 0.02; 0.32 ± 0.03 vs. 0.59 ± 0.08 and 0.31 ± 0.04 vs. 0.61 ± 0.03 g/5min, respectively. Heart performance was directly related to pH value (7.38 ± 0.06, 7.33 ± 0.03, 7.14 ± 0.04, 7.08 ± 0.04, 7.25 ± 0.03), the change in the rate pressure product being 21,702 ± 1969 vs. 21,291 ± 2,552; 22,098 ± 2,115 vs. 14,114 ± 3,386; 20,897 ± 2,083 vs. 10,671 ± 1,948; 21,822 ± 2,470 vs. 10,047 ± 2,320 and 20,955 ± 2,296 vs. 15,951 ± 2,755 mmHg × bpm, respectively.ConclusionsIt appears important to maintain the pH value within a physiological range to maintain optimal myocardial contractility. Using colloids prepared in calcium-containing, balanced solutions for volume replacement therapy may attenuate the breakdown of vascular barrier competence in the critically ill.
Highlights
Recent data suggested an interaction between plasma constituents and the endothelial glycocalyx to be relevant for vascular barrier function
Transudate formation and parameters related to heart performance (HP) showed no significant intergroup differences under basal conditions or between basal and second measurements in the control groups, respectively
A significant increase in transudate formation versus control conditions was observed in all study groups upon dilution of the modified, albumin-augmented Krebs-Henseleit buffer (KHB) by artificial solutions (Figure 3)
Summary
Recent data suggested an interaction between plasma constituents and the endothelial glycocalyx to be relevant for vascular barrier function This might be negatively influenced by infusion solutions, depending on ionic composition, pH and binding properties. For over 100 years vascular barrier competence was generally acknowledged to be sufficiently explained by the historical principle of Ernest Starling [1] This stipulated an inwardly directed oncotic gradient between an interstitial oncotic plasma pressure. Various experimental models showed that the interstitial oncotic pressure in most organs is far from zero and, surprisingly, does not relevantly influence transvascular filtration behaviour [2] This brought attention to the endothelial glycocalyx, a negatively charged layer of proteoglycans and glycosaminoglycans, identified as an important part of vascular barrier competence [3]. The fragile glycocalyx, can be degraded in various pathophysiological situations such as ischaemia/reperfusion, sepsis, hyperglycaemia, trauma or diabetes [6,7]
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