burning questions from the FA graphs of page 236-237 (10th edition)

[Shejeboshease]

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this is what i understand, please correct me if i'm wrong:

beta 1: will increase the systolic pressure by increasing contractility
beta 2: will decrease the diastolic pressure
alpha 1: will increase the diastolic pressure

now for the epinephrine curve of page 236, shouldn't there be an effect of alpha 1 which will counteract the decrease of diastolic pressure by beta 2?

for isoproterenol curve, why is the effect of beta 2 significantly larger than that of beta 1 given isoproterenol activates both of them equally?

for the epi curves on page 237, are they only showing the effects of alpha 1?

these curves always confuse me....if you guys have any simpler way to summarize all this, please let me know. thanks

also, how come you can't use epi for closed angle glaucoma? may be using epi will dilate the puplillary sphincter making the glaucoma worse....but i think this should actually help with relieving the pressure behind the iris?
thanks anyways

 

[knuckles]

this is what i understand, please correct me if i'm wrong:

beta 1: will increase the systolic pressure by increasing contractility
beta 2: will decrease the diastolic pressure
alpha 1: will increase the diastolic pressure

now for the epinephrine curve of page 236, shouldn't there be an effect of alpha 1 which will counteract the decrease of diastolic pressure by beta 2?

for isoproterenol curve, why is the effect of beta 2 significantly larger than that of beta 1 given isoproterenol activates both of them equally?

for the epi curves on page 237, are they only showing the effects of alpha 1?

these curves always confuse me....if you guys have any simpler way to summarize all this, please let me know. thanks

also, how come you can't use epi for closed angle glaucoma? may be using epi will dilate the puplillary sphincter making the glaucoma worse....but i think this should actually help with relieving the pressure behind the iris?
thanks anyways

epi will stimulate b2 -> increases ciliary epithelium aqueous humor production increasing IOP

 

[512TA]

epi will stimulate b2 -> increases ciliary epithelium aqueous humor production increasing IOP

isnt epinephrine (alpha agonist effect) used for glaucoma-- it decreases aqueous humor production. it should thus decrease IOP. it also causes mydriasis and stinging.

 

[512TA]

this is what i understand, please correct me if i'm wrong:

beta 1: will increase the systolic pressure by increasing contractility
beta 2: will decrease the diastolic pressure
alpha 1: will increase the diastolic pressure

now for the epinephrine curve of page 236, shouldn't there be an effect of alpha 1 which will counteract the decrease of diastolic pressure by beta 2?

for isoproterenol curve, why is the effect of beta 2 significantly larger than that of beta 1 given isoproterenol activates both of them equally?

for the epi curves on page 237, are they only showing the effects of alpha 1?

these curves always confuse me....if you guys have any simpler way to summarize all this, please let me know. thanks

also, how come you can't use epi for closed angle glaucoma? may be using epi will dilate the puplillary sphincter making the glaucoma worse....but i think this should actually help with relieving the pressure behind the iris?
thanks anyways

you will not want to use epinephrine for closed angle glaucoma because it will have no effect on opening the angle that is already closed. remember that epinephrine can cause ciliary muscle constriction and thus reduce aqueous humor formation.
in closed angle glaucoma its not overproduction thats a problem. instead it is the draining that is a problem.
let me know if you still have not got it.

 

[IMGUSMLEStep1]

I remember reading somewhere that topical epi on the eye only stimulates alpha receptors because it's broken down before it can reach the beta receptors in the ciliary body.

 

[aashkab]

i thought epinephrine WAS used for glaucoma (open angle) because it causes mydriasis and helps drain through canal of schlemm better. however, it doesn't work for closed angle glaucoma (makes it worse) because this same dilation causes the lens and iris to create even more of a block. and epinephrine does not MAKE more aqueous humor because like IMGUSMLEstep1 said, its broken down before it can reach the ciliary epithelium