AJP - Regulatory, Integrative and Comparative Physiology, Vol 268, Issue 3 731-R735, Copyright © 1995 by American Physiological Society
Interaction of the renal nerves and prostaglandins on the phosphaturic response to PTH in phosphate-deprived rats
T. J. Berndt, A. A. Khraibi and F. G. Knox
Department of Physiology, Mayo Clinic and Foundation, Rochester, Minnesota 55905.
Previous studies demonstrated that catecholamines modulate the phosphaturic
response to parathyroid hormone (PTH) in normal rats. The present study was
performed to determine the effect of unilateral renal denervation (DNX) and
the interaction with prostaglandin synthesis on the blunted phosphaturic
response to PTH in phosphate-deprived rats. One week before the acute
experiment, rats were anesthetized, and the left kidney was denervated or
sham surgery was performed. Rats were fed either a low-phosphate diet (LPD,
0.07%) or a normal-phosphate diet (NPD, 0.7%) for 2 days before the
experiment. All rats were thyroparathyroidectomized (TPTX). Control
clearances were taken from the left kidney 2 h after TPTX. PTH (33 U/kg + 1
U.kg-1.min-1) was infused for 45 min, and then the urine collections were
repeated. In phosphate-deprived rats with an innervated kidney, PTH
infusion resulted in a blunted phosphaturic response [changed fractional
excretion of phosphate (delta FEPi) of 9.2 +/- 3.7%, n = 9] compared with
rats fed NPD (delta FEPi 45.7 +/- 9.3%, n = 6) or those in the
phosphate-deprived group with renal DNX (delta FEPi 23.6 +/- 5.0%, n = 12).
Indomethacin pretreatment (3 mg/kg) markedly attenuated the phosphaturic
response to PTH in phosphate-deprived rats with a denervated kidney (delta
FEPi, 3.2 +/- 1.3%, n = 7) but not in animals fed an LPD with innervated
kidneys or in rats fed an NPD. Infusion of Iloprost (2 ng.kg-1.min-1), a
stable prostaglandin I2 analogue, in indomethacin-treated
phosphate-deprived rats enhanced the phosphaturic response to PTH in rats
with a denervated kidney (delta FEPi 17.3 +/- 3.5%).(ABSTRACT TRUNCATED AT
250 WORDS)
