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A 26-year-old man participates in an exercise study. He is appropriately classified as sedentary, since his VO2max (maximum oxygen consumption) measured during conventional cycle ergometer exercise is 35 mL/kg/min. The exercise study he participates in utilizes a knee-extensor ergometer that limits exercise to the quadriceps muscles. The subject is given a 5-minute unloaded warm-up, followed by a graded maximal exercise test, and then by 30 minutes of knee-extensor exercise at 50% of the maximum work load. A biopsy is taken from the exercising muscle using a 5 mm diameter biopsy needle sixty minutes after termination of the exercise routine. Which of the following would most likely be increased in the muscle sample?
A. Basic fibroblast growth factor mRNA
B. Intracellular pO2
C. Mitochondrial volume density
D. Myoglobin oxygen saturation
E. Vascular endothelial growth factor mRNA
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eee..
myoglobin O2 sat shud dec as it is released to give excercising muscle O2.mitochondrail density will take time to inc
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eee..
myoglobin O2 sat shud dec as it is released to give excercising muscle O2.mitochondrail density will take time to inc
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irum how long it will take for mRNA to show increment?they took the sample after 5 minutes of the exercise!!!
im between b and c
and B more
so waiting for biochem2 to reply!!
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The correct answer is E. Vascular endothelial growth factor (VEGF) is a heparin binding glycoprotein that increases endothelial cell proliferation in vitro and capillary growth (i.e., angiogenesis) in vivo. Unlike most other growth factors, VEGF has unique target cell specificity for vascular endothelial cells, i.e., it does not directly stimulate growth of other types of cells. VEGF mRNA expression is increased in human skeletal muscle within an hour following intensive exercise. This increase in VEGF mRNA expression is followed by increased VEGF protein levels, which can initiate angiogenesis in the muscles. Growth of new blood vessels decreases diffusion distances between capillaries and muscle fibers, thereby improving oxygen transport to the tissues.
Basic fibroblast growth factor (bFGF) (choice A) is a heparin-binding growth factor capable of stimulating angiogenesis. However, bFGF mRNA expression is not increased following an exercise routine such as that described in the vignette.
Exercise decreases myoglobin oxygen saturation (choice D) as well as intracellular pO2(choice B).
Endurance exercise training can stimulate growth of mitochondria in human skeletal muscle and thereby increase mitochondrial volume density (choice C) (i.e., volume of mitochondria per unit volume of muscle); however, growth of new mitochondria will not occur within an hour after exercise.
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toooooooooooooooooo much for me, all of u guys rock. u can actually discuss this q!!!!!!!!!
