Cardiac Fuels Flashcards
Almost ….. of cardiac emergy is generated from oxidative phosphorylation.
> 95%
….. of cardiac ATP is used for contraction, the rest is used for ….
60-70%
Fueling ion pumps esp Ca-ATPase
Mention ATP & PCr content of cardiac muscle & the turnover rate of ATP.
5 micromol/g (ATP)
8 micromol/g (PCr)
10s
PCr is formed from ATP by …., while ATP is formed from PCr by…..
Mitochondrial creatine kinase
Cytosolic creatine kinase
Mention the cardiac fuels & the two most used.
Fatty acid (major source, 80%)
Glucose metabolism (remaining quantity)
Lactate
Ketone bodiea
Mention effect of low to moderate exercise in contrast to effect of high intensity exercise on cardiac muscle metabolism
L to M, increased uptake of glucose from blood and lactate generated from skeletal muscle, without change in fatty acid oxidation.
H, glucose utilization relatively drops.
Glucose is transported though ……
GLTU-4, GLUT-1 (less)
Mention factors increasing rate of glucose transport and uptake.
Insulin stimulation, increased work demand or ischemia.
Net ATP production per 1 glucose molecule is ….
36-38
Mention factors which increse FFA level in plasma
Physical exercise, fasting or myocardial ischemia
FFA enter cardiomyocyte by …..& …
Passive diffusion or protein mediated transport
Mention fate of long chain fatty acyl CoA in cardiomyocyte
Either esterified to triacyglycerol OR converted to acycarnitine by CAT1 then transported into mitochondria, where AcylCoA is regenerated by CAT2 to share in beta-oxidation.
Net energy generated by beta-oxidation of palmitate.
129 ATP
The two functional water soluble KB are ……
Acetoacetate
3-hydroxybutyrate
The primary physiological regulator of PDH activity is ……
Fatty acid oxidation
The mechanism by which FA oxidation inhibits PDH
Increase mitochondrial acetyl-CoA/free CoA and NADH/NAD+ which activates PDH kinase
Stressful conditions increase …. which stimulate ….., resulting in inhibition of …. oxidation
Catecholamines
Lipolysis
Glucose
Mention the downstream effects of of high anaerobic glycolysis and low glucose oxidation in cardiac muscle.
Lactate and protons accumulate leading to myocardial tissue acidosis. Accumulation of lactate can kead to accumulation sodium and calcium so more ATP is needed for homeostasis. This redirection of ATP from contraction to ion homeostasis decreases cardiac efficiency.
+futile cycles
Write a short note of futile cycles.
- CAUSED BY increased fatty acids decreasing cardiac efficiency by
- Activation of fatty acids to long chain acul CoA forming TAG uses ATP
- Increasing uncoupling proteins activity
- High fatty acids activate sarcolemal calcium channels, so more ATP is needed for homeostasis.
Mention the role of metabolic agents in heart disease & give an example
Inhibits fatty acid oxidation partly and stimulate glucose and lactate oxidation which can improve cardiac efficiency and cardiac function in ischemic heart failure.
Trimerazidine in angina pectoris
