Abstract P316: Gonad Dependent Changes in Kallikrein Kinin System Behavior and Renal Electrolyte Excretion after Rectifying Outer Medulla K + Channel Blockade in Spontaneously Hypertensive Rats

The kallikrein kinin system (KKS) is involved in blood pressure (BP) regulation by a mechanism not completely defined. Our previous reports have shown that high K + intake or prepuberal gonadectomy (Gx) diminish BP with a simultaneous increase in urine kallikrein activity (UKa) and plasma aldosterone (PA) levels, revealing a link between those systems. Thus, since K + may be involved in the regulation of KKS, we explored the rectifying outer medulla K + (ROMK) channel blockade using glibenclamide (Gli) in different gonad contexts.Spontaneously hypertensive rats of both sexes, half of them Gx at weaning, were studied at 12 weeks of age (n = 32). Glucose solution (4%) with or without Gli (10 mg/kg bwt) was orally administered in the last 3 days of the experiment. We analyzed BP, glomerular filtration rate, PA, daily urine Na + and K + excretion and UKa. Renal cortex kallikrein activity (RKa) and UKa were determined by colorimetric assay. Renal mRNA levels of Kcjn1 (ROMK), Atp1α1 (Na + K + Atpase) and Klk1 (kallikrein 1) genes were determined by quantitative real time PCR. Urine Na + /K + increased after Gli treatment (0.55 ± 0.03 vs 1.34 ± 0.30, p <0.05) due to a K + excretion decrease in intact male and ovariectomized rats and to a Na + excretion increase in intact female. These changes were concomitant with increased GFR within the normal range (0.51 ± 0.06 vs 0.76 ± 0.06 ml/min/100g bwt p < 0.01) and no differences in BP and PA among groups. After Gli treatment, renal cortex Klk1 and RKa levels increased in intact males (297 and 137 %, p < 0.05, respectively), while in orchidectomized group Klk1 and UKa levels increased (179 and 230 %, p < 0.05; respectively). Kcjn1 and Atp1α1 mRNA levels decreased in renal medulla of all groups (1.29 ± 0.28 vs 0.32 ± 0.11 and 0.94 ± 0.23 vs 0.20 ± 0.02, p < 0.01, respectively). Taken together, gonad dependent changes were seen in urine Na + and K + excretion and KKS behavior after ROMK blockade without changes in the BP and aldosterone. Moreover, the repression in Kcjn1 and Atp1α1 genes could be related to the observed ion transport changes.