<p>Acute Renal Medullary Interstitial Infusion of either saline or 2% albumin indistinctly rises RIHP and RMBF in the rat. M. Eugenia Sánchez-Briones, Juan F. López-Rodríguez, Miriam Z. Calvo-Turrubiartes and Manuel Rodríguez-Martínez, Physiology & Biophysics Dept. School of Medicine, UASLP, San Luis Potosi, S.L.P. Mexico</p><p>The effects of an acute renal medullary interstitial infusion (RMII) of 100 µl of either 0.9% saline (Sal) or 2% albumin in saline (Alb) on the time course (30 min) of renal interstitial hydrostatic pressure (RIHP, subcapsular), renal medullary blood flow (RMBF, L-D), urinary nitrogen oxides excretion (UNOxV, Griess) and urinary flow (V) were assessed in the denervated kidney of anesthetized male Wistar rats with renal perfusion pressure (RPP) controlled at 100 mmHg. After a 10 min control period (CP) and a 15s RMII period, three 10 min post-infusion periods (PIP) of urinary collections were generated. The results are mean ± SEM; ^ p<0.05 vs. CP. Group CP RMII PIP 10min 20 min 30 min RIHP Sal 3.0 3.8 3.9 5.3 6.8 (mmmHg) n=17 ±0.4 ±0.5 ±0.5^ ±0.7^ ±0.8^ Alb 3.0 3.2 3.5 4.0 4.8 n=17 ±0.3 ±0.3^ ±0.3^ ± 0.5^ ±0.7^ RMBF Sal 0.0 2.0 10.7 12.5 8.2 (%∆) n=17 ± 3.4 ±3.3^ ±4.0 ± 4.3 Alb 0.0 2.2 9.1 6.6 8.7 n=17 ± 5.0 ±4.5^ ± 4.7 ± 5.2 There were no differences between groups in UNOxV nor in V through time. Conclusions: Acute RMII of either 0.85% saline or 2% albumin indistinctly rises RIHP and RMBF in the anesthetized rat, without affecting UNOxV nor urinary flow at all.</p>