23 Lipids - Fatty acid vs CHO metabolism

23 Lipids - Fatty acid vs CHO metabolism - Attention:...

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What are YOU doing next summer? If interested contact: Dr. Good @ [email protected] How about applying to the USDA Scholars Program? Attention: Sophomores and Juniors DEADLINE: Friday, December 4, 2009 2007 HNFE Scholars 2008 USDA Scholars 2009 USDA Scholars
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The Facts Work with a faculty member on a research project Entire summer (May – August) Financial support ($4500) Must apply by December 4 th 5 pm
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Fuel Utilization/Regulation: Fat vs. CHO HNFE 3025 Fall 2009
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Fuel Oxidation Oxidation of glucose C 6 H 12 O 6 + 6 O 2 6 CO 2 + 6 H 2 O Oxidation of a fatty acid-palmitic acid C 16 H 32 O 2 + 23 O 2 16 CO 2 + 16 H 2 O Review Slide 4
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RQ vs. RER RQ: respiratory quotient is the ratio of CO 2 produced to O 2 consumed: Usually based on small tissue samples Based on measures made across a limb using venous and arterial measures of O 2 2 and measures of blood flow RER: respiratory exchange ratio: the ratio of VCO 2 to VO 2 based on measures of respiratory gases and ventilation. Measured at mouth Whatever is used, RQ or RER, we learn the proportions of CHO and Fat that are oxidized since 1.0 is pure CHO and 0.7 is pure fat. Reality is in between. Review Slide 5
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Reciprocal Relationship Fatty acid oxidation and glucose oxidation function in a reciprocal manner if CHO oxidation goes up, FA oxidation goes down and vice versa If fatty acid oxidation can easily handle ATP needs, CHO oxidation is reduced: Reductions in pyruvate metabolism at the pyruvate dehydrogenase (PDH) step Increase in cytosolic citrate inhibits phosphofructokinase activity What else inhibits PFK? 6
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_ + + Four isoforms for PDHK, main one PDHK 4 in skeletal muscle, but also PDHK 2 1 PDHK activities increased by indices of elevated energy & redox status in mitochondria Main effect of an ADP 7
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8 Allosteric Modulators of PFK1 Reminder: For even a slight decrease in ATP there is a correspondingly larger increase in ADP, and a really large increase in AMP. Therefore, changes in [AMP] are a really important intracellular signal of a change in energy metabolism. If it goes up, the cell needs to crank up ATP-generating processes. If there is little change in [AMP], there is little change.
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AMP is a Potent Signaling Agent Normally, the concentration of AMP in a cell is very low (<< 1μM concentration). Exercise or stress results in sharply increased levels of ATP hydrolysis and an increased concentration of ADP. Adenylate kinase combines two ADP to make an ATP and an AMP. Therefore the increase in cellular [AMP] parallels the
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This note was uploaded on 03/23/2010 for the course HNFE 3025 taught by Professor Mwhulver during the Spring '10 term at Virginia Tech.

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23 Lipids - Fatty acid vs CHO metabolism - Attention:...

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