Lecture 6: Cardiomyocyte Growth Physiology

Question 1

When does calcium peak?

Answer 1

Starts before contraction and peaks before cell shortens

Question 2

What receptor activates the Na/H exchanger and what does this cause?

Answer 2

Alpha 1, makes cell more alkaline - increased contraction

Question 3

What do AT1/AT2 promote?

Answer 3

Rapid contractile response, fibroblast collagen production, repair, growth, fibrosis

Question 4

What does Mas downregualte?

Answer 4

Fibrosis, BP, hypertrophy

Question 5

What effect does beta 1 have on calcium?

Answer 5

Increase calcium entry

Question 6

What effect does alpha 1 have on calcium?

Answer 6

Increase calcium sensitivity

Question 7

What effect do Ang II and ET-1 have on calcium?

Answer 7

Increase sensitivity and entry

Question 8

What are levels of Ang II related to?

Answer 8

Heart mass - thicker walls and larger individual muscle cells

Question 9

What activates AT1 and AT2?

Answer 9

Ang II

Question 10

What activates Mas?

Answer 10

Ang I-VII

Question 11

What do oncogenes do?

Answer 11

Initiate growth response

Question 12

When is AT2 most abundant and what is it important for?

Answer 12

Pre and neonatally - important for remodelling of the heart

Question 13

What do AT1 receptors signal?

Answer 13

Miocene growth postnatally

Question 14

What do AT1 & AT2 mediate?

Answer 14

Apoptosis

Question 15

What is a whole heart replacement/abicor?

Answer 15

Whole heart inserted and major vessels reattached - operates at 5-9k revs /min as opposed to 60 revs /min by a normal heart.

Question 16

What was the problem with whole heart replacement?

Answer 16

Patients couldn’t feel a heart beat, hard to get interface between existing and artificial vessels - lots of clot formation

Question 17

What are the features of the 1st gen VADs?

Answer 17

Pulsatile pumps, many moving parts, large

Question 18

What are the features of the 2nd gen VADs?

Answer 18

Continuous flow, small, need anticoagulation, only for patients with severe at rest symptoms who do not respond to therapy within 60 days

Question 19

What are the advantages of 2nd gen VADs?

Answer 19

Only one moving part, no wearing surfaces, reliable, 7-10L blood/min, small

Question 20

What are the disadvantages of 2nd gen VADs?

Answer 20

Infection risks with percutaneous leads to external battery, device malfunction, patient cannot be removed from battery at any time, weak or no pulse

Question 21

What are the risks of mechanical heart devices?

Answer 21

Thrombus, heparin coating, endothelial tissue growth of blood contacting surfaces, not economically viable

Question 22

When are mechanical device used?

Answer 22

As a bridge to transplant or as a last resort if transplant is not possible

Question 23

What happens when there is a sustained increased cardiac workload?

Answer 23

Alkalinity maintained, calcium levels increased, oncogenes activated, structural and functional adaptation of the heart