CARNITINE PALMITOYL TRANSFERASE & FATTY ACID METABOLISM

运动生理学的一个中心问题是如何保持平衡 骨骼肌中碳水化合物和脂肪酸氧化之间的关系 改变以满足肌肉收缩的新陈代谢需求。我们是 用~(13)C核磁共振和非稳态同分异构体分析 定量测定大鼠体内两种竞争底物的相对氧化 骨骼肌。我们发现[13C]乙酸酯和[13C]乳酸是 由静息和收缩的骨骼肌摄取和氧化， 高强度的肌肉收缩改变了 底物的利用使醋酸酯的相对氧化 降低，而乳酸保持不变或增加。 然而，由于~(13)C核磁共振的灵敏度较低，我们不得不汇集两个 腓肠肌和四块比目鱼肌，以获得 可解释的13C核磁共振波谱。为了克服这一限制，我们 最近开发并验证了一种更灵敏的分析方法 用~1H核磁共振技术对组织提取物中的~(13)C进行了浓缩。使用这一新的 方法：取大鼠腓肠肌(~1.5) 比目鱼肌(~0.15克湿重)。谷氨酸C4 用~1H核磁共振测得的富集值与 通过~(13)C核磁共振非稳态同位异构体分析获得测量结果。 我们现在正在应用同样的技术来检查肌肉新陈代谢。 在老鼠身上。初步结果表明，核磁共振氢谱是灵敏的。 足以检测到富含谷氨酸C4的萃取物 小到小鼠比目鱼肌的组织样本(湿重10毫克)。 (协作性5)报告期：(09/01/97-08/31/98)

A central question in exercise physiology is how the balance between carbohydrate and fatty acid oxidation in skeletal muscle is altered to meet the metabolic demands of muscle contraction. We're using 13C NMR and non-steady-state isotopomer analysis to directly quantify the relative oxidation of two competing substrates in rat skeletal muscle. We found that [13C]acetate and [13C]lactate were taken up and oxidized by both resting and contracting skeletal muscle, and that high-intensity muscle contractions altered the pattern of substrate utilization such that the relative oxidation of acetate decreased while that of lactate remained unchanged or increased. However, because of the low sensitivity of 13C NMR, we had to pool two gastrocnemius muscles and four soleus muscles in order to acquire interpretable 13C NMR spectra. To overcome this limitation, we recently developed and validated a more sensitive method to analyze 13C enrichment in tissue extracts using 1H NMR. Using this new method, we have obtained data from individual rat gastrocnemius (~1.5 g wet weight) and soleus (~0.15 g wet weight) muscles. Glutamate C4 enrichment values obtained by 1H NMR were highly correlated with measurements obtained by 13C NMR non-steady-state isotopomer analysis. We are now applying these same techniques to examine muscle metabolism in mice. Our preliminary results indicate that 1H NMR is sensitive enough to detect glutamate C4 fractional enrichment in extracts from tissue samples as small as the mouse soleus muscle (10 mg wet weight). (Collaborative 5) REPORT PERIOD: (09/01/97-08/31/98)