The Impact of Total Unilateral Ureteral Obstruction on Intrarenal Angiotensin II Production in the Polycalyceal Pig Kidney

Abstract

Nine pigs with unilateral complete ureteral obstruction were investigated for 15 hours. Obstruction of the ureter resulted in a maximum intrapelvic pressure of 60 cmH₂O within the first hour after obstruction, and a gradual decline to 40 cmH₂O during the next 15 hours. In 6 pigs both renal veins were catheterized together with the abdominal aorta allowing measurement of the hormonal difference over the kidney. Plasma angiotensin II, plasma vasopressin and plasma atrial natriuretic peptide concentrations were determined. Arterial concentration of plasma angiotensin II gradually increased from 38.7 pg/ml to 252.3 pg/ml. The highest concentrations of angiotensin II were found from the ipsilateral renal vein. From 1 hour after obstruction and onward there was a negative extraction ratio of angiotensin II from the ipsilateral kidney indicating enhanced intrarenal generation of angiotensin II. No difference in vasopressin was found among the sample sites, but a significant reduction in vasopressin from 15.2 pg/ml to 4.9 pg/ml was found from the ipsilateral renal vein during the 15 hours of unilateral ureteral obstruction. Arterial atrial natriuretic peptide concentrations were higher than renal venous levels at all times. Glomerular filtration was immediately reduced to 58%. It is suggested that an increased ipsilateral generation of intrarenal angiotensin II is at least partly responsible for some of the changes in kidney function during acute obstruction.

Key words:

• angiotensin II
• atrial natriuretic peptide
• blood pressure
• pelvic pressure
• pigs
• potassium
• renal function
• obstructive nephropathy
• vasopressin