Lecture 6: Cardiomyocyte Growth Physiology Flashcards
When does calcium peak?
Starts before contraction and peaks before cell shortens
What receptor activates the Na/H exchanger and what does this cause?
Alpha 1, makes cell more alkaline - increased contraction
What do AT1/AT2 promote?
Rapid contractile response, fibroblast collagen production, repair, growth, fibrosis
What does Mas downregualte?
Fibrosis, BP, hypertrophy
What effect does beta 1 have on calcium?
Increase calcium entry
What effect does alpha 1 have on calcium?
Increase calcium sensitivity
What effect do Ang II and ET-1 have on calcium?
Increase sensitivity and entry
What are levels of Ang II related to?
Heart mass - thicker walls and larger individual muscle cells
What activates AT1 and AT2?
Ang II
What activates Mas?
Ang I-VII
What do oncogenes do?
Initiate growth response
When is AT2 most abundant and what is it important for?
Pre and neonatally - important for remodelling of the heart
What do AT1 receptors signal?
Miocene growth postnatally
What do AT1 & AT2 mediate?
Apoptosis
What is a whole heart replacement/abicor?
Whole heart inserted and major vessels reattached - operates at 5-9k revs /min as opposed to 60 revs /min by a normal heart.
What was the problem with whole heart replacement?
Patients couldn’t feel a heart beat, hard to get interface between existing and artificial vessels - lots of clot formation
What are the features of the 1st gen VADs?
Pulsatile pumps, many moving parts, large
What are the features of the 2nd gen VADs?
Continuous flow, small, need anticoagulation, only for patients with severe at rest symptoms who do not respond to therapy within 60 days
What are the advantages of 2nd gen VADs?
Only one moving part, no wearing surfaces, reliable, 7-10L blood/min, small
What are the disadvantages of 2nd gen VADs?
Infection risks with percutaneous leads to external battery, device malfunction, patient cannot be removed from battery at any time, weak or no pulse
What are the risks of mechanical heart devices?
Thrombus, heparin coating, endothelial tissue growth of blood contacting surfaces, not economically viable
When are mechanical device used?
As a bridge to transplant or as a last resort if transplant is not possible
What happens when there is a sustained increased cardiac workload?
Alkalinity maintained, calcium levels increased, oncogenes activated, structural and functional adaptation of the heart
