Establishment Of A Local Spastic Model In The Rabbit Abdomenal Aorta And Discussion On The Pathogenetic Mechanisms

Background:There are two kinds of spastic disorders in vivo condition, which are variant angina with coronary artery spasm and Raynaud?s syndrome with acromelic artery spasm.The etiology and pathogenesis have remained unclarified. Although,in variant angina,spasm usually occurs at the site of atherosclerotic plaque,it may also develops in angiographically normal arteries.It has been demonstrated that angiographically noraml arteries usually progress at the early stage of atherosclerosis.In addition to other atherosclerotic risk factors,the most significant risk factor in variant angina is cigarette smoking compared with those in effort angina pectoris.All kinds of atherosclerotic risk factors might lead to vascular endothelial dysfunction, which is charactered by impaired endothelium-dependent vasorelaxation.It relates to characteristics of coronary artery spasm. Objectives:(l) To establish a local spastic model in the rabbit abdomenal aorta in vivo condition,which is similar to characteristics of CAS;(2) To elucidate the essence of CAS that coronary artery is probably hypercontractive to many kinds of stimuli based on vascular EDF by relationship between atherosclerotic risk factors and vascular spasm;(3) To clarify the factors that influence vascular spasm by relationship between vasomotor responses and serum cholesterol levels. Methods:24 New Zealand White rabbits(9 male and 15 female) with body weight 2.40?.50 (2.83 ?.30) kg were subjected to three groups in the study.Balloon endothelial denudation was performed at level of L34 lumbar vertebra in the abdomenal aorta. After denudation,Erg(0.2 mg),Hist(20 ^tg 1kg), L-NMMA(l00 pmol), NTG(10 ^tg/kg) were injected respectively in aorta,of which injection interval between two agonists was 15 20 minutes.Angiography was performed 1 3 minutes after injection. The femoral artery was tied up and the incision was sutured.Then,rabbits were send back animal room and were fed on diet respectively.Rabbits in group 1 were fed on a diet containing 2% cholesterol for eight weeks and those in group 2 were fed on a diet containing 0.4% cholesterol for eight weeks.In group 3,rabbits were fed on a diet containing 0.4% cholesterol and then were fed a regular diet for eight weeks either.The rabbits were tested once more and shared the same protocol.Blood samples were obtained to be analysed blood lipids in each study.Histological study was examined for denuded and control vessels in the second experiment.Vasomotor responses were measured by abdomenal aorta angiography before and after injection of agonists. Results:( 1) Body weights of rabbits changed unnoticeably.Vascular diameters at denuded and control vessels 8 or 16 weeks later reduced slightly,but were not statistically significant compared with those at 0 week;(2) Serum cholesterol level in group 1 was considerably higher than that in group 2 or 3(p<0.00 1) and there was a statistically significance between group 2 and 3(p5 Vascular spasm could also be induced by pain stimulus,the extent of which was larg...