CARNITINE PALMITOYL TRANSFERASE & FATTY ACID METABOLISM

运动生理学的一个中心问题是， 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代谢需求。 我们 使用13 C NMR和非稳态同位素分析， 定量大鼠体内两种竞争底物的相对氧化 骨骼肌 我们发现[13 C]乙酸盐和[13 C]乳酸盐是 被静止和收缩的骨骼肌吸收和氧化， 高强度的肌肉收缩改变了 底物利用率使得乙酸盐的相对氧化 而乳酸则保持不变或增加。 然而，由于13 C NMR的低灵敏度，我们不得不将两个 腓肠肌和四个比目鱼肌，以获得 可解释的13 C NMR谱。 为了克服这一局限性，我们 最近开发并验证了一种更灵敏的方法来分析 使用1H NMR在组织提取物中富集13 C。 使用这种新 方法，我们从单个大鼠腓肠肌（~1.5 g湿重）和比目鱼肌（约0.15g湿重）肌肉。 谷氨酸C4 通过1H NMR获得的富集值与 通过13 C NMR非稳态同位素异构体分析获得的测量值。 我们现在正在应用这些相同的技术来检查肌肉代谢 对小鼠 我们的初步结果表明，1H NMR是敏感的 足以检测提取物中谷氨酸C4的部分富集， 小至小鼠比目鱼肌的组织样品（10 mg湿重）。 （协作5）报告期：（1997年9月1日至1998年8月31日）

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)