A new method to denude the endothelium without damage to media: structural, functional, and biomechanical validation

Abstract

A new method to denude the endothelium without damage to media: structural, functional, and biomechanical validation. Am J Physiol Heart Circ Physiol 286: H1889-H1894, 2004; 10.1152/ ajpheart.00863.2003.-The intimial thickening that occurs in human and animal atherogenesis can be induced by mechanical injury to the endothelium. The objective of the present study was to develop a new method to induce arterial endothelial injury without damage to the media for future investigations of mechanisms of intimal thickening and atherogenesis. A specifically designed catheter was inserted into the common femoral artery of Wistar rats (n ϭ 9) through an arteriotomic mouth. After application of Tyrode solution containing 0.14 M KCl on the surface of the vessel, the vessel contracted onto the catheter. The catheter was then moved back and forth to scrape away the endothelium. The left common femoral artery of the same rat was subjected to the standard balloon injury model. The two models were evaluated structurally, functionally, and biomechanically. Structurally, we verified that both techniques remove the endothelium, but the balloon method damages the media. Functionally, we examined the contractile response of the artery to [K ϩ ] and norepinephrine 2 days after the denudation. We found that the right femoral artery underwent contraction in response to [K ϩ ], whereas the left artery did not. Furthermore, neither artery responded to norepinephrine. Biomechanically, we measured the pressure-diameter relationship and the zero-stress state of the vessel and computed the stress-strain relation. The circumferential stretch ratios at 120 mmHg were 1.38 Ϯ 0.08 for the control, 1.41 Ϯ 0.08 (P Ͼ 0.05) for the new method, and 1.56 Ϯ 0.09 for the balloon injury (P Ͻ 0.05). The opening angles at the zero-stress state were 113 Ϯ 21°for the control, 102 Ϯ 18°for the new method (P Ͼ 0.05), and 8 Ϯ 13°for the balloon injury (P Ͻ 0.001). In conclusion, the new method removes the endothelium while maintaining the structure, contractile function, and biomechanical properties of the vessel. injury; zero-stress state; balloon injury; endothelin THE ENDOTHELIAL CELLS that line the lumen of the blood vessel are extremely important for the normal function of the vessel. The endothelium is the largest autocrine, paracrine, and endocrine organ that regulates vessel tone, monocyte adhesion, platelet activation, thrombogenesis, inflammation, lipid metabolism, vessel growth, and remodeling (21, 23). Because endothelial injury is an important risk factor for atherosclerosis, numerous models of endothelial injury have appeared in the literature (10,12,13). Previous investigations have induced endothelial injury mechanically (via balloon distension, microsurgical instrument, or air desiccation) or chemically (via hydrochloric acid or Triton X-100) (2, 12). The most widely used model, however, is injury induced by a balloon overinflated into the lumen of the vessel and dragged along the lumen to scrape off the endothelium. Unfortunately, this technique...

Diabetic eNOS knockout mice develop distinct macro- and microvascular complications

“…For example, the use of air bubbles failed to remove endothelial cells completely at the region of interest, whereas, using chemicals, it was difficult to have control over the area of endothelial-cell denudation. 25 Use of the mechanical guide wires and balloon distensions on the other hand could damage the media including the smooth muscle cells and elastin fibers beyond endothelium.…”

NADPH oxidase has a directional response to shear stress

“…Five segments were incubated with L-arginine (1 mM), whereas five segments were incubated with N G -monomethyl-L-arginine (L-NMMA; eNOS inhibitor, 0.4 M). Three segments were mechanically denuded with a suture attached to a metal ring (35). The segments incubated with L-arginine or L-NMMA were stimulated with acetylcholine (10 Ϫ7 M).…”

Endothelial Denudation of Isolated Human Internal Mammary Artery Segments

“…Lu et al used a specifically designed catheter in constriction abrasion method to successfully denude the artery of Wistar rat [16]. Other successful denudation methods employed in animal vascular reactivity studies include: gentle rubbing of the luminal surface of the vessel with wooden stick [8], syringe needle [9], stainless steel wire [10,11], forcept [12], blunt seeker [13], balloon catheter [14,15] and intense vascular constriction upon a intravascular rod [16]. This clearly illustrates the differences between animal and human isolated vessel studies.…”

“…The rod was then carefully moved back and forth three times within the vessel lumen thereby removing the endothelium. This is a hybrid approach to similar methods that utilise an inflated balloon catheter rather than the stainless steel rod as described previously by Lu [16].…”

“…catheter [14,15], (2) intense vascular constriction upon a intravascular rod [16] and (3) the passing of air bubbles through the lumen of the vessel [17]. Similar studies utilising the human internal mammary artery (IMA) have been problematic and met with variable success in achieving consistent endothelial denudation, since the vessel is not amenable to the above established denudation techniques.…”