Sympathetic stimulation and filtration fraction

[Kovach]

Can someone please explain effects of sympathetic stimulation on GFR, renal plasma flow and filtration fraction? As I understood from Kaplan lectures- there's increase in FF with decrease in GFR and RPF, but UW says there's no change in GFR in sympathetic stimulation

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[JP2740]

I would think there's an increase in GFR. Angotensin II ->eff arteriole>aff arteriole constriction -> increase GFR, decrease RPF -> increase FF. Could someone explain why GFR is going down?

 

[FIREitUP]

I would think there's an increase in GFR. Angotensin II ->eff arteriole>aff arteriole constriction -> increase GFR, decrease RPF -> increase FF. Could someone explain why GFR is going down?

i would think because of decreased blood flow to the kidney due to sympathetic mediated vasoconstriction of the renal artery via alpha-1 receptor (use dopamine to vasodilate)

 

[Choo]

sympathetic innervation constricts afferent arteriole decreasing GFR and RPF. B1 stimulation of the JG cells will lead ultimately to increased aldosterone.

 

[Kovach]

sympathetic innervation constricts afferent arteriole decreasing GFR and RPF. B1 stimulation of the JG cells will lead ultimately to increased aldosterone.

So, what's with filtration fraction? Anyone?

 

[Choo]

So, what's with filtration fraction? Anyone?

There should be no change at first since afferent arteriole constriction results in no change in FF. But, if I am understanding it correctly, catecholamines binding to the B1 receptors on JG cells will lead to angiotensin II which will constrict efferent arterioles. That should further reduce RPF and increase GFR, so FF will eventually increase. I'm not entirely sure about all this. Someone correct me if I'm wrong.