Early effects of uninephrectomy on K homeostasis in unanesthetized rats.
Mechanisms underlying the change in K excretion (UKV) during the first 6 days after uninephrectomy (UNX) were examined in unanesthetized rats. Arterial plasma K concentrations (PK) were 0.55 meq/l above control values at 12 and 24 h after UNX but were not significantly different 36-72 h after UNX. To determine if there was an increased sensitivity of the distal K secretory mechanism to increases in PK, an intragastric KCl infusion was given. The delta UKV/delta PK per kidney values were in the following order: 6-day UNX > 2-day UNX > control. In the normal rats, an acute increase of 0.5 meq/l in PK increased UKV by an amount approximating 25% of the increase in UKV observed 12-24 h after UNX. Amiloride, administered 48 h after UNX, increased Na excretion per kidney and decreased UKV per kidney approximately twice as much in UNX as in control groups. Thus an adaptive increase of amiloride-inhibitable K secretion occurred within 2 days of UNX and continued to increase thereafter. This K adaptation may have been induced by transient increases in PK.
Aizman
R I
RI
Department of Human Physiology, University of California, Davis 95616, USA.
Rabinowitz
L
L
Mayer-Harnisch
C
C
D000222:Adaptation, Physiological; D000284:Administration, Oral; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002940:Circadian Rhythm; D005260:Female; D006706:Homeostasis; D009392:Nephrectomy; D009994:Osmolar Concentration; D011188:Potassium / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000652:urine; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000097:blood
D011189:Potassium Chloride; D000584:Amiloride; D012964:Sodium; D011188:Potassium