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I was doing a question today that states that giving propanolol in angina would worsen the situation since beta 2 receptors which normally mediate vasodilation would be blocked and alpha one which mediate vasoconstriction would be unapposed. This is a bit confusing to me since beta 1 really are working on the heart whilst beta two are for the lungs, how does a beta blocker work on the heart in general does anyone know? for some reason this question isn't making any sense to me. also what is the role of alpha ones in this? I mean why are beta blockers prescribed at all then? thought they slow down the heart rate so where did all this other stuff come from? please help
thanks
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propranol is non selective so blocks both b1 and b2 receptors, thus it can slow down heart ( tru b1 action) plus it can block vasodilatation ( tru b2).
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so why is this not a good treatment for angina? how would it exacerbate it, if in fact it can slow the heart rate it would translate to less exertion no? when is it better to subscribe a beta blocker then? thank you
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i'm not sure of the treatment of angina, but if the propranolol will cause vasoconstriction ( due to blocking b2 receptors which cause vasodilation) it's bad because less blood will flow in coronary if vessel is constricted. Also in vasoconstriction heart has to do more work to overcome afterload.
Maybe instead of propranolol a beta-1 selective beta blocker (which would only slow heart but not cause vasoconstriction) would be used.
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I think the main thing in the question u did was propranolo being NON SELECTIVE blocks both b1 and b2 receptors, compared to other drug blocking only b1 receptors
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yes, I think the "focus" of the answer to the original q or in their explnation they confused me somewhat. the answer was a ca2+ channel blocker would be best. the fellow in the q was on sildenfil so couldnt be put on nitrates, and propanolol was apparently also a bad choice, needless to say my answer to that q probably would have killed the patient in real life since I didn't even see that viagra in there. Seems like all the important clues fall on my blind spot =(
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well this is an eye opener, if u see it again u will remem and choose the correct answer. Remem in addition to testing our knowledge, the questions also teach us things.
