The effect of intraarterial infusion of prostacyclin on the tubuloglomerular feedback control in the rat.

Effects of intraarterial prostacyclin (PGI2) infusions on interstitial hydrostatic and oncotic pressures and on the tubuloglomerular feedback (TGF) control of glomerular filtration rate (GFR) were studied in rat kidneys. The hilar lymph flow rate was used as a measure of interstitial hydrostatic pressure and the lymph protein concentration was used for interstitial oncotic pressure estimation. In the micropuncture experiments the stop-flow pressure technique was employed for determining the TGF characteristics, i.e. stop-flow pressure (PSF), maximal reduction of PSF (delta PSF) and turning point (TP), defined as the end-proximal flow rate at which 50% of delta PSF was obtained. Non-hypotensive doses of PGI2 (50 to 100 ng X kg-1 B.W. X min-1) infused in 30 min evoked an increase in urine and lymph flow rates and a decrease in lymph protein concentration, but did not affect GFR. delta PSF was reduced (9.9 +/- 1.0 mmHg versus 4.7 +/- 2.2 mmHg) and TP increased (22 +/- 2 nl/min versus 34 +/- 2 nl/min), but the PSF was unaffected. These changes were seen during the infusion period and during the immediate post-infusion control period of 30 min. Our data indicate that non-hypotensive doses of PGI2 in some way can affect the renal interstitial pressure and the TGF control system.