Haddad F, Baldwin K M
Department of Physiology and Biophysics, University of California, Irvine 92717.
Am J Physiol. 1991 Jun;260(6 Pt 1):E920-6. doi: 10.1152/ajpendo.1991.260.6.E920.
Previous studies have shown that dietary carbohydrate (CHO) can impact on cardiac isomyosin expression in hormonally deficient animals. The primary objective of this study was to determine whether a high-CHO diet alters cardiac isomyosin expression in severe thyroid-deficient rats. Also the effects of targeting the heart with episodes of biasing cardiac metabolism toward CHO were studied. Female Sprague-Dawley rats were assigned to one of two major groups: 1) normal control and 2) thyroidectomized (TX) propylthiouracil treated. The TX rats were allocated into four experimental subgroups as follows: 1) mixed diet; 2) high-CHO diet; 3) high-CHO diet and treated with oxfenicine, a fatty acid oxidation inhibitor; and 4) high-CHO diet, treated with oxfenicine, and trained. Results show that, at the end of 12 wk of thyroidectomy, there was a marked shift in cardiac isomyosin distribution to predominance of the V3 isoform. However, 6 wk of experimental manipulation failed to redirect cardiac isomyosin expression in TX rats. It is concluded that increased CHO utilization does not influence cardiac isoenzyme expression in markedly hypothyroid female rats. Dietary effects of CHO on cardiac isomyosin require some critical level of thyroid hormone for mediating the response.
以往的研究表明，膳食碳水化合物（CHO）可影响激素缺乏动物的心脏异肌球蛋白表达。本研究的主要目的是确定高CHO饮食是否会改变严重甲状腺功能减退大鼠的心脏异肌球蛋白表达。同时，还研究了通过使心脏代谢偏向CHO的方式对心脏产生的影响。雌性Sprague-Dawley大鼠被分为两个主要组：1）正常对照组和2）甲状腺切除（TX）并用丙硫氧嘧啶治疗组。TX大鼠又被分为四个实验亚组，如下：1）混合饮食组；2）高CHO饮食组；3）高CHO饮食并用脂肪酸氧化抑制剂奥芬尼辛治疗组；4）高CHO饮食，用奥芬尼辛治疗，并进行训练组。结果显示，甲状腺切除12周结束时，心脏异肌球蛋白分布发生明显转变，以V3亚型为主。然而，6周的实验操作未能使TX大鼠的心脏异肌球蛋白表达发生重新定向。研究得出结论，在明显甲状腺功能减退的雌性大鼠中，增加CHO利用并不会影响心脏同工酶表达。CHO对心脏异肌球蛋白的膳食影响需要一定临界水平的甲状腺激素来介导这种反应。
