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ANP effects on filtration fraction/proximal reabsorption

Discussion in 'Step I' started by nguyen1025, Mar 17, 2013.

  1. nguyen1025

    nguyen1025 7+ Year Member

    Nov 7, 2008
    From my understanding, angiotensin II raises the filtration fraction (constriction of efferent arteriole) which raises the osmotic pressure and lowers the hydrostatic pressure, thus causing an increase in proximal tubular reabsorption. So does ANP also do this since it raises the filtration fraction also? (Dilation afferent, constriction efferent). This all just seems a little counter intuitive to me.
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  3. owenwilsonwoah


    Mar 4, 2018
    Ressurrecting this old thread.

    I had this question myself.

    Here's my guess.

    Afferent dilation > Efferent constriction.

    Afferent dilation = higher GFR, higher RBF

    Efferent constriction = Higher gfr, lower RBF.

    Since Afferent is greater, there is a net increase in RBF and the two positive effects on GFR increase it dramatically.

    So the Filtration fraction is increased.

    More fluid is filtrated and at the same time, ANP leads to decreased renal Na+ reabsorption, leading to an increase in fluid excretion.

    Anyone else have any thoughts?
    Last edited: Mar 14, 2018 at 5:42 AM

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