Palace V P, Hill M F, Khaper N, Singal P K
Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Center, Winnipeg, Canada.
Free Radic Biol Med. 1999 Jun;26(11-12):1501-7. doi: 10.1016/s0891-5849(99)00013-1.
The supply of vitamin A to the myocardium by storage organs during increased oxidative stress subsequent to myocardial infarction (MI) was examined in hemodynamically assessed rats using compartment analysis of a radio-labeled vitamin A. 3H-Vitamin A was injected into two groups of rats: an MI group and a control group. There were no differences in the plasma or myocardial content of total vitamin A (unlabeled + labeled) between the two groups. However, the proportion of 3H-vitamin A was greater in the myocardium as well as plasma of MI rats. Rats with MI also had significantly lower 3H-vitamin A levels in liver and kidney than sham controls. The greatest difference in vitamin A content was in the concentrations of 3H-labeled storage forms of vitamin A in the liver of MI animals. Activity of bile salt-dependent retinyl ester hydrolase, an enzyme responsible for hydrolyzing vitamin A storage forms, was significantly increased in the liver of MI animals. These data indicate that analysis of plasma concentrations of vitamin A to ascertain links to cardiac conditions may be inappropriate. Specifically, during MI, increased amounts of vitamin A are mobilized from the liver to the heart without changing plasma concentrations. This is facilitated by an increase in the activity of an enzyme that hydrolyzes vitamin A storage forms.
利用放射性标记维生素A的区室分析方法，在血流动力学评估的大鼠中，研究了心肌梗死（MI）后氧化应激增加期间储存器官向心肌供应维生素A的情况。将3H-维生素A注射到两组大鼠体内：MI组和对照组。两组之间总维生素A（未标记+标记）的血浆或心肌含量没有差异。然而，MI大鼠的心肌和血浆中3H-维生素A的比例更高。与假手术对照组相比，MI大鼠肝脏和肾脏中的3H-维生素A水平也显著降低。维生素A含量的最大差异在于MI动物肝脏中3H标记的维生素A储存形式的浓度。负责水解维生素A储存形式的胆盐依赖性视黄酯水解酶的活性在MI动物的肝脏中显著增加。这些数据表明，通过分析血浆维生素A浓度来确定与心脏疾病的联系可能并不合适。具体而言，在MI期间，维生素A的量从肝脏动员到心脏，而血浆浓度没有变化。这是由水解维生素A储存形式的酶活性增加所促进的。
