The effect of tubular perfusion with PGE2, PGF2 alpha, and PGI2 on the tubuloglomerular feedback control in the rat.

The prostaglandins (PG) of the renal medulla might affect the nephron and the cortical arteriolar function via the tubular route. To investigate this question PGE2 (1 microgram/mL), PGF2 alpha (10 micrograms/mL), or PGI2 (1 ng/mL) was added to the tubular perfusion solution when the characteristics of the tubuloglomerular feedback (TGF) control were measured. The experiments were performed on Sprague-Dawley rats. The proximal tubular stop-flow pressure (PSF) was measured upstream to a wax block, while at the same time the distal nephron was perfused with prostaglandin-containing or prostaglandin-free solutions at different flow rates varying from 0 to 50 nL/min. The maximal drop in PSF (delta PSF) and the tubular flow rate at which 50% of the delta PSF response was obtained, the turning point (TP), were determined. When PGE2 or PGF2 alpha was added to the tubular perfusion solution in the control animals a significant increase in feedback sensitivity was found. After 10 min of tubular PGI2 perfusion the feedback sensitivity was almost completely abolished, with a delta PSF of 0.8 mmHg (1 mmHg = 133.322 Pa) (control 8.4 mmHg) and a TP of greater than 40 nL/min (control 22 nL/min). After nephrectomy the feedback sensitivity was reduced, with a delta PSF of 2.0 mmHg and a TP of greater than 40 nL/min. When PGE2 was added to the tubular perfusion solution in the uninephrectomized animals, the feedback sensitivity was increased to the control level, with a delta PSF of 8.2 mmHg and a TP of 20.0 nL/min.(ABSTRACT TRUNCATED AT 250 WORDS)