Derangement of pH homeostasis in the renal papilla: ochratoxin A increases pH in vasa recta blood.
It is reported that ochratoxin A (OTA) impairs urinary acidification by increasing the urinary pH and also increases the intracellular pH in Madin-Darby canine kidney cells. This study was designed to examine whether OTA deranges pH homeostasis in the interstitium (or vasa recta) of the renal papilla. Rats were injected once with OTA (3 micromol/kg body weight) intravenously (acute application) or with OTA (1.25 micromol/kg body weight/day) intraperitoneally for 6 days (subchronic application). We measured the pH values in both the descending and ascending vasa recta blood (VR) in the renal papilla. Both the acute and subchronic applications of OTA led to significant increases in pH values in both descending and ascending VR by 0.4-0.6 pH units. However, no significant increases in pH values in renal arterial and aortic blood in OTA-treated rats were observed. We also examined the pH changes in collecting-duct urine after OTA injection (3 micromol/kg body weight). We found a significant increase in pH values 30 min after OTA injection; this significant elevation of pH values was present during the whole experiment (120 min). The results of this study suggest that OTA deranges pH homeostasis in the interstitium of the renal papilla, in addition to the impairment of urinary acidification.
Kuramochi
G
G
Department of Physiology, University of Wurzburg, Germany.
Gekle
M
M
Silbernagl
S
S
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D006706:Homeostasis / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D007679:Kidney Medulla / Q000187:drug effects / Q000378:metabolism*; D007685:Kidney Tubules, Collecting / Q000378:metabolism; D008297:Male; D009793:Ochratoxins / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D002121:Calcium Channel Blockers; D009793:Ochratoxins; C025589:ochratoxin A