nbme 3 q

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nbme 3 q

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ladybug
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Topics: 20
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04/28/06 - 11:10 PM

calcium channel blockers are effective antiarrythmic agents because they inhibit calcium influx in

a. AV node

b. bundle of his

c. cardiac muscle of atria

d. cardiac muscle of ventricels

e. smooth muscle of coronary arteries

robin082006
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04/28/06 - 11:14 PM

D?

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asterixis
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04/29/06 - 05:11 AM

ladybug
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04/29/06 - 08:36 PM

All of the clinically-approved Ca++-channel blockers:

Decrease coronary vascular resistance and increase coronary blood flow Decrease peripheral resistance via vasodilatation of arterioles Are without significant effect on venous tone at normal doses

Is it E? I'm still reading up on it. I duno the answer yet? Anyone out there knows?

asterixis
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04/30/06 - 08:59 AM

Ok, here is what I've found. The calcium channel blockers as antiarrhythmics block the two locations where impulses depend on Ca for their action potentials, the SA node and AV node, therefore the drug decreases phase 4 slope, decreases the rate of the rise of phase 0 (the AP), and increases the refractoriness. But as an antianginal it causes coronary vasodiltation and decreases cardiac contractility, because they inhibit nucleotide phosphodiesterases which increase cGMP and cAMP. So that makes me think it's A.

drpkaur
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04/30/06 - 09:51 AM

it's A for sure

yasmeen
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04/30/06 - 10:09 AM

A IS RIGHT

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