Longitudinally orientated smooth muscle cells in rabbit arteries

Abstract

Intima formation in vessels, spontaneous or experimentally induced, is generally characterized by the presence of longitudinally oriented smooth muscle cells (LSMC). During an experiment of neo-intima induction in carotid arteries in rabbits, by application of a non-constrictive silastic cuff, a study was performed to investigate the presence of LSMC in the systemic and pulmonary circulations, in both elastic and muscular arteries. Three patterns could be distinguished: intimal cushions in muscular arteries, single or small groups of LSMC in the intima in elastic and larger muscular arteries, and intra-medially located layers or columns of LSMC in the aorta, the pulmonary artery, at the bifurcation of the aorta and around orifices of branches. In order to understand this peculiar orientation a biomechanical approach was used: this showed that near the lumen the circumferential stress is 4.5 times higher than the longitudinal. Because the cell surface of the smooth muscle cells exposed to this stress per unit vessel length is much less in the longitudinal than in the circular direction we conclude that the LSMC align in the direction which allows them to cope most effectively with the mechanical stresses.

Von Willebrand Factor Inhibits Mature Smooth Muscle Gene Expression through Impairment of Notch Signaling

“…Most recently, we have shown novel functions of vWF including activation of immediate early genes and suppression of smooth muscle marker genes [24]. A number of studies have raised the possibility that vWF may stimulate non-canonical activities that drive intimal thickening [41] [42] [43]. This report presents the new concept that vWF represses expression of genes encoding mature smooth muscle proteins by inhibiting Notch function.…”

“…Previous work has implicated vWF in smooth muscle proliferation [41], [42], [43]. However, vWF impairment of Notch is probably not solely responsible for cell proliferative responses since chemical inhibition of Notch signaling with DAPT did not activate mitosis.…”

Airway smooth muscle orientation in intraparenchymal airways

“…Although this finding is intriguing, there is no obvious explanation for it. Smooth muscle has been described as being helically arranged in other tubular structures, including the gut (9,15), the ureter (14), and the vasculature (12). In these organs, the musclaris is far more complete than in the airways, and muscle fibers are arranged in well-defined layers that may run perpendicular to each other.…”

The relationship between pre-existing subendothelial smooth muscle cell accumulations and foam cell lesions in cholesterol-fed rabbits

“…Fat accumulation in the arterial wall correlates with the distance from the lumen, shows in the initial stages no topographical predilection and is not associated with the LSMC. In our previous study [13] we presented evidence that LSMC structures are an expression of increased circumferential stress implicating a haemodynamic mechanism. FC plaques are frequently associated with anatomical structures like curves or branchings but they occur also frequently in straight non branching arteries of which the common carotid is a good example.…”

“…5). Since LSMC are never present in rabbit pulmonary veins [13], the plaques develop independently, as in many arterial segments not containing LSMC. Staining for vWF demonstrated a conspicuous increase of immunoreactive material in the EC covering the plaques compared to the adjacent EC (Figs.…”