The breeding for development of myocardial infarction in WHHL rabbits

Watanabe遗传性高脂血症（WHHL）兔从出生就表现出高脂血症，这是由于低密度脂蛋白受体的遗传缺陷。主动脉和冠状动脉粥样硬化在该动物中发生在过早的年龄。然而，心肌梗死在幼兔中并不常见。我们进行了选择性繁殖，试图增加这种连接的发生率在WHHL兔。本研究对88只选育后的肉兔（MI系）与93只选育前的肉兔（非MI系）进行了比较，以评价其选育效果。结果如下：1）.非MI系平均狭窄率为56%，MI系F_1为66%，MI系F_3为77%，MI系F_4为78%。2）。在非MI系中，狭窄超过75%的频率为26%，而MI系的F_1、F_3和F_4分别增加到41%、67%和75%。3）。非MI线的心肌梗死发生率为13%，MI线的F1、F3和F4的心肌梗死发生率分别增加至15%、26%和25%。4）。10月龄以上的WHHL兔发生心肌梗死后冠状动脉狭窄率均在75%以上，而10月龄以下的WHHL兔发生心肌梗死后冠状动脉狭窄率与心肌梗死无关。5）。雄兔心肌梗死发生率明显高于雌兔。因此，我们认为冠状动脉狭窄和心肌梗死都是由于选择性繁殖而扩大的。

The Watanabe heritable hyperlipidemic (WHHL) rabbit shows hyperlipidemia from birth, owing to a genetical deficiency of the low density lipoprotein receptors. The aortic and coronary atheros-clerosis occur at a premature age in this animal. However, myocardial infarction does not develop often in the yound rabbits. We carried out selective breeding in an attempt to increase in the incidence of this lision in WHHL rabbits. In this study 88 rabbits after selective breeding (MI-line) sere compored with 93 rabbits before selective breeding (non MI-line) in order to estimate the breeding effect. The results were as follows : 1). The average of the percent of narrowing was 56% in non MI-line, 66% in F1 of MI-line, 77% in F3 of MI-line and 78% in F4 of MI-line. 2). The frequency of over 75% narrowing was 26% in non MI-line and increased to 41% in F1, 67% in F3 and 75% in F4 of MI-line. 3). The incidence in myocardial infarction was 13% in non MI-line and increased to 15% in F1, 26% in F3 and 25% in F4 of MI-line. 4). WHHL rabbits aged over 10 months in which myocardial infarction provoked were always observed over 75% narrowing in coronary arteries, whereas in the rabbits aged under 10 months there were no relation between myocardial infarction and the severe coronary narrowing. 5). The incidence of myocardial infarction in the male rabbits was significantly higher than that in the female. Consequently, we considered that both coronary narrowing and myocardial infarction were expanded because of the selective breeding.