Heart Failure and Hypertrophy (Chronic Cardiac Adaptation)

Question 1

What MHC isoforms are found in the heart?

Answer 1

α and β MHC isoforms

Question 2

T or F: different MHC heterodimers have distinct ATPase activity

Answer 2

True, and functional properties

Question 3

How is the expression of α and β MHC regulated?

Answer 3

transcriptionally regulated

Question 4

What changes are seen in phenotypically distinct models of cardiac hypertrophy?

Answer 4

Myosin isoform and ATPase shifts

Question 5

What specific changes are seen in pathological hypertrophy?

Answer 5

Decrease in ATPase

and increase ββ MHC

Question 6

What specific changes are seen in physiological hypertrophy?

Answer 6

Increase in ATPase

and in αα MHC

Question 7

What causes pathological hypertrophy?

Answer 7

Aortic valve stenosis

chronic hypertension

Question 8

What causes physiological hypertrophy?

Answer 8

Chronic exercise

Pregnancy

Question 9

T of F: In response to stress, both the quantity and the quality of the contractile elements is altered

Answer 9

True

Question 10

The phenotypic adaptions may involve what?

Answer 10

both transcriptional and post-translational modifications (Most imp point in this lecture)

Question 11

T or F: The functional adaptations can lead to ventricular dysfunction over time

Answer 11

True

Question 12

What are the cellular mechanisms behind left ventricular hypertrophy (LVH)?

Answer 12

• Likely increase in Ca current via L-type Ca channel
• Reduced SR pump fxn (↑ PLB/SERCA2 ratio)
• Impaired myofilament relaxation
• Altered (increased) cytosolic calcium and new steady-state

Question 13

What is the proposed transcriptional regulation of gene expression in cardiac cells?

Answer 13

Calcineuron dephosphorylates NFAT allowing passage to nucleus where it acts as a transcription factor