I measured collagen levels in ventricular tissue lysates of spontaneously hypertensive heart failure rats and expected to get higher levels than the controls. but what I found was the opposite. The collagen levels were significantly reduced and I am not sure why this is so. Any ideas or explanation of why the collagen level may have been reduced? thank you
What age were your SHR? You are correct in thinking the levels should be higher, but this is usually when they are ~18 months old. What method did you use?
collagen is wound healing protein.finrosis maybe complete .because of this reason itwas low.
you can defend it.
how did you measure collagen ?
Also, I think it is possible a relative reduction of collagen by cardiac muscle hypertrophy. If you can, perform a mesurement of muscle fiber width. May you attach images?
Hello, we are studying a model of heart failure induced by mechanical injury and also observed a transient decrease in collagen levels in association with structural changes in collagen. Firstly should you check if the content or synthesis of collagen has been normalized to the content or synthesis of total proteins. This is important to ensure that the results are indeed correct. Then you should investigate if the model presents necrotic cardiomyocytes, because necrosis is one of the most important stimuli for the production of collagen.
There are many factors that should be considered for discussion of the results. Are you following all stages of heart failure? Has the model experienced symptoms? Is heart dysfunction present?
Good luck!
Hi
We can not say only one factor because there are many factors for example cardiac muscle hypertrophy or healing protein and and another facter,,,,
hello everyone. Thank you for your responses. here are some answers to provide more information about my experimental setting.:
1) The SHHF rats were only 4 months old. At this age, they do not have systolic dysfunction yet but exhibited prolonged IVRT (ie diastolic dysfunction), which led me into looking at markers of fibrosis.
2) I measured Collagen I protein by western blotting lysates from left ventricular tissue. The LV tissues were taken near the apex of the heart.
I am looking for ideas to discuss the result.
Bolanle
Hello Bolanle,
Both destruction (loss) and deposition of collagen occur in heart failure. Collagen destruction occurs prior to fibrosis deposition and changes the geometry and function of the myocardium throughout an up-regulation of metalloproteases. It is possible that at the time of their evaluations, collagen destruction prevailed over deposition. Did you quantify the expression of metalloproteases?
Generally, collagen loss deprives the myocardium of its supporting structure and may represent the early stage of a systolic dysfunction.
With regard to diastolic dysfunction, as seen by you, it can occur in the absence of fibrosis. Diastolic dysfunction without fibrosis is not very common in humans, however it is often observed in dogs. You need to consider that in a scenario of myocardial hypertrophy, changes in the distribution, configuration, and organization of collagen fibers, as well as in the proportions of type I and type III collagens, are sufficient to cause diastolic dysfunction.
I also believe that you should consider the age factor, as proposed by Marie.
We can not say only one factor because there are many factors for example cardiac muscle hypertrophy or healing protein and and another facter,,,,
Thanks Marcela for your contribution,
Can you recommend any references to support the idea that collagen destruction precedes collagen deposition in Fibrosis?
I did not measure metalloproteases but I have read in another paper that characterized SHHF rat model, that gene expression for matrix metalloproteases was increased. But this was also accompanied by increased expression of TIMP (tissue inhibitors of matrix metalloproteases). Probably collagen protein levels were reduced due to high breakdown by the MMP... just my thoughts
Hi Bolanle,
I'm sending you some references that will probably help you
Interstitial Fibrosis in Heart Failure. Edited by Francisco Villarreal. eBook ISBN 978-0-387-22825-9. DOI 10.1007/b99419
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4430981/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1087861/
http://www.sciencedirect.com/science/article/pii/S0735109710801275
https://www.ncbi.nlm.nih.gov/pubmed/22516365
http://circ.ahajournals.org/content/85/4/1483
https://link.springer.com/chapter/10.1007%2F978-1-4615-1893-8_24
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