AJP - Renal Physiology, Vol 250, Issue 1 66-F69, Copyright © 1986 by American Physiological Society
Lack of a direct effect of atrial natriuretic factor in the rabbit proximal tubule
M. Baum and R. D. Toto
Whole animal clearance studies and in vitro microperfusion studies were
performed to examine the effect of atrial natriuretic factor (ANF) on the
rabbit proximal tubule. Infusion of ANF into rabbits resulted in an
increase in glomerular filtration rate and a natriuresis and diuresis. To
determine whether ANF has a direct proximal tubule effect to account for
part of the observed natriuresis, proximal convoluted tubules (PCT) and
proximal straight tubules (PST) were perfused in vitro. Addition of 10(-9)
M ANF, a concentration recently measured in vivo during volume expansion,
to the bathing solution of PCT caused no significant change in volume
absorption. Addition of a pharmacological concentration of ANF (10(-7) M)
to either the bathing solution or the luminal perfusate of PCT resulted in
no change in volume absorption. When added to the bathing solution of PST,
10(-7) M ANF did not have an effect on volume absorption. ANF did not
affect the transepithelial potential difference in any protocol. In
conclusion, these data show that ANF does not affect transport directly in
the proximal tubule.
