AJP - Renal Physiology, Vol 237, Issue 3 226-F231, Copyright © 1979 by American Physiological Society
Effect of potassium deficiency on papillary plasma flow in the rat
M. A. Whinnery and R. T. Kunau Jr
Chronic potassium (K+) deficiency has been shown previously to cause a
reduction in solute content in the renal papilla, an effect that is
potentially important as a contributing factor to the concentrating defect
seen in this circumstance. The cause of the decrease in papillary solute
content has not been adequately explained. Because alterations in the blood
flow rate through the renal papilla may affect the solute content of the
papilla, the present experiments examined the effect of chronic K+
deficiency on papillary plasma flow (PPF) in the rat. PPF was measured by
the radioactive albumin accumulation technique. Sprague-Dawley rats were
fed identical quantities of water and either a normal or a K+-deficient
diet for 21 days. Total GRR in the control rats, 1.7 +/- 0.17 (SE) ml/min,
was similar to that in K+-deficient rats, 1.4 +/- 0.14 ml/min (P greater
than 0.01). Total [3H]PAH clearance was also comparable in the two groups,
i.e., 4.4 +/- 0.47 in control and 4.7 +/- 0.45 ml/min in K+-deficient rats
(P greater than 0.06). PPF was significantly lower in K+-deficient rats,
19.7 +/- 1.1 ml-min-1-100 g-1, than in control rats, 59.8 +/- 1.6
ml-min-1-100 g-1 (P less than 0.001). The decrease in PPF in the
K+-deficient rat may reflect a reduction in perfusion to the juxtamedullary
nephrons, thereby resulting in a diminution in both solute delivery and
blood flow to the papilla.
