drpkaur
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q) a moderate pressor dose of NE is given after prett with a large dose of atropine,which of the following is most probable response to the ne?
a A dec in HR caused by direct cardiac effect
b a dec in HR caused by indirect reflex effect
c an increase in HR caused by direct cardiac action
d an inc in HR caused by indirect reflex action
e no chnge in HR
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| khorshid
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e?
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| drkaur
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hey
NE act on alpha1 2 and beta 1 but atropine on m#so i think no effect ??????????????
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| Dragonfly
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c. alpha effect of NE causes vasoconstriction and inc. BP which would decr. HR via reflex by activating the vagus (M-receptors)
but surprisingly, M-receptors are shut off by atropin already !!
but that doesn`t stop NE from its direct effect on the heart via Beta-1 receptors.
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| sridevibandaru24
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c. alpha effect of NE causes vasoconstriction and inc. BP which would decr. HR via reflex by activating the vagus (M-receptors)
but surprisingly, M-receptors are shut off by atropin already !!
but that doesn`t stop NE from its direct effect on the heart via Beta-1 receptors.
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| sridevibandaru24
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what Dragonfly said is right
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| drpkaur
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C.atropine will block the reflex bradYcardia cause by NE.
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| giovanni83
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yes you are right.
I've got a curiosity: epinephrine instead increase heart rate anyway,right?that's one of the most important differences between E and NE
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| young_doc
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yup. Because with Epi, there isn't a big change in MAP (due to both alpha1 and B2...which kinda cancel each other out). So there's no reflex tachy/brady. So all that's left is Epi's B1 stimuation, hence tachycardia.
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