mesh
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how does acidosis leads to decreased contractility of heart and decreased stroke volume.
can nebody explain .thanx
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| KrazyK
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I'm not 100% sure this is right but this makes sense to me:
Increased EC H+ causes a shift of H+ into the cell and K+ out of the cell, causing hyperkalemia (see Kaplan Phys Notes; Renal Phys Ch. 3 - K+ Dynamics in Acidosis).
Hyperkalemia results in depolarization of resting membrane potential (see Kaplan Excitable Tissue Chapter). Why? Since cell is permeable to K+ at rest, changing K+ will change RMP. In what direction? The increased extraceullar K+ means there is less of a gradient driving K+ out of the cell, so less K+ will diffuse out of the K+ channels and more K+ will be in the cell than before there was hyperkalemia. More of an intracellular positive ion means the cell will have a higher resting potential (in other words, depolarized at rest).
If there is another mechanism, let me know. Thanks.
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| mesh
Forum Guru
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Posts: 401
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thanx for the explanation
but can u explain this in relation to intracellular ca2+ ion conc.cauz contractility depends on it.
can increased H+ ion conc lead to decreased intracellular calcium leading to decrease in contractility.i hope i'm making sense.
thanks.
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| ssrpk
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http://www.prep4usmle.com/forum/thread/20360
http://www.prep4usmle.com/forum/thread/10301
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