The effect of 17 beta-estradiol 3-benzoate (10 micrograms.01 ml of sunflower oil-1 x 100 g body wt-1) on the temporal pattern of exercise-induced tissue glycogen depletion and tissue lipid availability during submaximal treadmill running was determined in male rats. Animal were administered estradiol or oil for 5 days and were then time matched for motorized treadmill running for 30, 60, 90, or 120 min. Significant depletion of liver, soleus muscle, and red and white vastus lateralis muscle tissue glycogen occurred in oil-administered animals run between 30 and 120 min. The greatest extent of tissue glycogen depletion occurred during the first 30 min of exercise with the rate of glycogen depletion slowing between 30 and 120 min of exercise. Administration of estradiol attenuated the temporal pattern of glycogen depletion in both liver and muscle tissues. Significant depletion of red and white vastus glycogen of estradiol-administered animals did not occur until 90 and 120 min of exercise, respectively. Administration of estradiol significantly increased resting plasma free fatty acids and red and white vastus triacylglycerol content. These data indicate that estradiol administration for 5 days resulted in significant glycogen sparing of liver and muscle tissues during submaximal treadmill running for up to 120 min by altering the temporal pattern of glycogen depletion of male rats secondary to an estradiol-mediated increase in availability of lipid substrate during exercise.
When fluorescently labeled contractile proteins are injected into embryonic muscle cells, they become incorporated into the cells' myofibrils. In order to determine if this exchange of proteins is unique to the embryonic stage of development, we isolated adult cardiac myocytes and microinjected them with fluorescently labeled actin, myosin light chains, alpha-actinin, and vinculin. Each of these proteins was incorporated into the adult cardiomyocytes and was colocalized with the cells' native proteins, despite the fact that the labeled proteins were prepared from noncardiac tissues. Within 10 min of injection, alpha-actinin was incorporated into Z-bands surrounding the site of injection. Similarly, 30 sec after injection, actin was incorporated into the entire I-bands at the site of injection. Following a 3-h incubation, increased actin fluorescence was noted at the intercalated disc. Vinculin exchange was seen in the intercalated discs, as well as in the Z-bands throughout the cells. Myosin light chains required 4-6 h after injection to become incorporated into the A-bands of the adult muscle. Nonspecific proteins, such as fluorescent BSA, showed no association with the myofibrils or the former intercalated discs. When adult cells were maintained in culture for 10 days, they retain the ability to incorporate these contractile proteins into their myofibrils. T-tubules and the sarcoplasmic reticulum could be detected in periodic arrays in the freshly isolated cells using the membrane dye WW781 and DiOC6[3], respectively. In conclusion, the myofibrils in adult, as in embryonic, muscle cells are dynamic structures, permitting isoform transitions without dismantling of the myofibrils.
This paper describes a quantitative analytical procedure to determine the fatty acid composition in drying oils like linseed, walnut and poppy seed. The procedure required the enzymatic hydrolysis of the oil triacylglycerol families by the action of Candida rugosa lipase. The fatty acids (FFAs) produced (linolenic, myristic, linoleic, palmitic, oleic and stearic) were extracted with n-heptane and derivatized with α-bromoacetophenone. Their separation and quantitative determination were performed by high-performance liquid chromatography employing a C18 column and an isocratic elution method coupled to ultraviolet detection. The analytical enzymatic procedure is sensitive for < 0.5 µg/mL of FFAs in a reduced sample of 0.1 mg of drying oil.
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