cAMP dependent Protein Kinase A in Myocytes - USMLE Forums
USMLE Forums Logo
USMLE Forums         Your Reliable USMLE Online Community     Members     Posts
Home
USMLE Articles
USMLE News
USMLE Polls
USMLE Books
USMLE Apps
Go Back   USMLE Forums > USMLE Step 1 Forum

USMLE Step 1 Forum USMLE Step 1 Discussion Forum: Let's talk about anything related to USMLE Step 1 exam


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 02-21-2013
USMLE Forums Scout
 
Steps History: Not yet
Posts: 19
Threads: 6
Thanked 26 Times in 6 Posts
Reputation: 36
Default cAMP dependent Protein Kinase A in Myocytes

Hi everyone,
I needed some help with a roadblock.
It regards the role of cAMP dependent Protein Kinase A. In smooth muscles, it supposedly phosphorylates and inhibits Myosin Light Chain Kinase, thereby restricting muscle contraction.
However, the B1 receptor in cardiac muscles is a Gs coupled receptor, meaning it will increase the concentration of cAMP. What's the mechanism for increased chronotropy and inotropy due to activation of the B1 receptor when cAMP concentration is increased?
Reply With Quote Quick reply to this message



  #2  
Old 02-21-2013
MedicalExaminer's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 824
Threads: 66
Thanked 462 Times in 298 Posts
Reputation: 472
Default cAMP

increased cAMP increases phase 4 slope (fNa channels) + increase Ca influx in sa node that increase rate of depolarization and shortens PR interval in AV node (phase 0)
in ventricles increase Ca influx causes more Ca release from sarcoplasm (Ca induced Ca release) + phosphorylates phospholamban that pumps more Ca into sarcoplasm than outside the myocyte leading to increased force of contraction

by the way increased HR through staircase effect increases inotropism too
__________________
Everything is possible for him who believes (MARK 9:23)
245/247/passed on 1st attempt/223/2mos Obsie /3 US LORS/visa not needed/2008 grad

Last edited by MedicalExaminer; 02-21-2013 at 06:27 AM.
Reply With Quote Quick reply to this message
The above post was thanked by:
ashratnam (05-17-2013)



Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the USMLE Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Medical School
Choose "---" if you don't want to tell. AMG for US & Canadian medical schools. IMG for all other medical schools.
USMLE Steps History
What steps finished! Example: 1+CK+CS+3 = Passed Step 1, Step 2 CK, Step 2 CS, and Step 3.

Choose "---" if you don't want to tell.

Favorite USMLE Books
What USMLE books you really think are useful. Leave blank if you don't want to tell.
Location
Where you live. Leave blank if you don't want to tell.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
DNA-dependent DNA polymerase lemontea88 USMLE Step 1 Forum 13 01-12-2013 07:17 PM
Fibroadenoma ~ estrogen dependent ? alice USMLE Step 1 Forum 0 11-08-2012 11:21 AM
cAMP inducers Mnemonic rapiddo USMLE Step 1 Mnemonics 2 04-07-2012 12:57 AM
dependent part usmleman2020 USMLE Step 1 Forum 4 08-17-2011 07:56 PM
RNA/DNA Dependent RNA/DNA Polymerases! kemoo USMLE Step 1 Forum 1 01-18-2011 12:28 PM

RSS Feed
Find Us on Facebook
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

USMLE® & other trade marks belong to their respective owners, read full disclaimer
USMLE Forums created under Creative Commons 3.0 License. (2009-2014)