Fj. Dowell et al., EFFECTS OF MANIPULATION OF DIETARY-CHOLESTEROL ON THE FUNCTION OF THETHORACIC AORTA FROM NEW-ZEALAND WHITE-RABBITS, Journal of cardiovascular pharmacology, 27(2), 1996, pp. 235-239
Animal studies, while generally showing loss of endothelium-dependent
responses after an elevation in plasma cholesterol, have provided conf
licting reports with regard to recovery of function after normalisatio
n of cholesterol level. Therefore, we assessed changes in vascular fun
ction after a period of hypercholesterolaemia and the subsequent effec
t of normalisation of cholesterol levels. Contractile responses to phe
nylephrine (PE) and endothelium-dependent relaxation in response to ca
rbachol were examined in thoracic aorta from New Zealand White rabbits
(NZW) fed a 0.3% cholesterol diet for 20 weeks, from NZW fed a 0.3% c
holesterol diet for 20 weeks, followed by standard diet for 20 more we
eks, and from their respective age-matched controls. Cholesterol level
s were increased in rabbits receiving the 0.3% cholesterol diet (12.7
+/- 3.2 mM; 0.5 +/- 0.1 mM control) and returned to normal when standa
rd diet was reintroduced (0.8 +/- 2.0 mM). Contractile responses were
not affected by the period of hypercholesterolaemia. Carbachol-induced
relaxation of a submaximal PE contraction was impaired after the peri
od of hypercholesterolaemia (E(max) 69 +/- 9%; 95 +/- 3% age-matched c
ontrol); the effect was reversed after reintroduction of standard diet
(E(max) 79 +/- 6%; 82 +/- 2% age-matched control). Our results demons
trate that endothelium-dependent relaxation is impaired after a long-t
erm 0.3% cholesterol diet. Furthermore, after reintroduction of a norm
al diet, there is no further impairment of endothelium-dependent relax
ation and endothelium function improves.