The glycocalyx of the endothelium of the systemic arteries and vena cava of the rabbit was visualised by in situ perfusion fixation with glutaraldehyde containing Alcian blue. The thickness of the layer ranged from 45 ± 1 nm in the coronary artery to 81 ± 2 nm in the carotid. The glycocalyx was 20 ± 1.5 nm thicker on the downstream side of intercostal ostia than on the upstream side. Changes in the staining pattern with increasing concentrations of MgCl₂ indicated that carboxyl groups made the major contribution to the surface charge, though sulphate groups were also present, particularly in the aortic arch and carotid artery. Segments of the thoracic aorta and carotid artery were also stained in vitro with fluorescence labelled wheat germ agglutinin, and fluorescence intensity in histological sections was quantified using a video microscope equipped with a microcomputer-based image analysis system. The fluorescence intensity in the carotid was 1.65 ± 0.15 times that in the aorta. Pretreatment with neuraminidase reduced fluorescence intensity by 60 ± 4% in the carotid and 53 ± 2% on the upstream side of intercostal ostia, but only by 37 ± 3% on the downstream side. Chondroitinase and heparanase both reduced binding and when used together their effect was additive, reducing fluorescence by 27 ± 3, 51 ± 4, and 32 ± 3% at the three sites, respectively. Though the interpretation of the lectin binding experiments is complicated by a number of factors, these results support previous reports that sialyl groups are abundant in the endothelial glycocalyx. Glycosaminoglycans are also present, however, in significant amounts.

We have investigated the effects of changes in solution composition on the mechanical properties of rings of arterial elastin. The time course of force equilibration at constant strain following a change in the composition of the bathing solution was measured. Both the force developed during slow extension and force relaxation following rapid straining were also measured in each of the test solutions. The results are difficult to summarize because all of the primitive quantities measured--sample dimension, slope of the force-extension curve, force overshoot and time of relaxation--as well as the derived quantities such as elastic modulus changed in different and apparently uncorrelated ways. Changes in pH and ionic composition of the bathing solution had small effects consistent with the low fixed charge density of elastin. Solutions of glucose, sucrose, and ethylene glycol had larger effects consistent with changes in hydrophobic interactions. The viscosity of the solution that penetrated the intrafibrillar space of the elastin appeared to be a major determinant of the dynamic response.

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In collateral deficient myocardium, the extent of myocardial necrosis is dependent on the level of solute exchange occurring during ischaemia. The level of solute exchange during reflow is dependent on the duration of ischaemia.