The aim of the present study was to examine the effect of
PMNs products, from control (CTL) and from 8-weeks (8 WK)
cholesterol-fed rabbits, on isolated normal and atherosclerotic aortic
strips with and without endothelium. Hypercholesterolemia was
induced by feeding rabbits I% cholesterol for 8 weeks. Isolation of
rabbit PMNs was done from CTL and 8WK cholesterol-fed rabbits.
Plasma cholesterol level was significantly elevated in 8WK rabbits,
and this was accompanied by significant development of
atherosclerotic lesions in aortic arch and abdominal aorta_ In organ bath
chambers, cu. and 8WIC PMNs products caused contraction of
precontracted normal and atherosclerotic aortic strips with intact
endothelium This contraction was significantly increased with 8WK
PMNs products. However, the contractile response of atherosclerotic
strips was significantly less than that of control strips. Moreover, CTL
PMNs products had no effect on precontracted aortic strips without
endothelium, resting tension of aortic strips with and without
endothelium. However, endothelium removal did not prevent but
attenuated the contraction caused by 8 WK PMNs products on
precontracted aortic strips or their resting tension. In addition, it was
t;)ti rid that ACh-induced relaxation of precontracted aortic strips was
i'nilicantly impaired in atherosclerotic strips compared to control
-1,es When 8WK PMNs products were added, ACh-induced relaxation
. significantly attenuated in both types of strips. In conclusion,
PM Ns products-induced contraction was endothelium-dependent.
I loNse‘er, hypercholesterolemia provided an endothelium-independent
component to that contraction. |
