The effects of ionizing irradiation on production of thromboxane and prostacyclin by the isolated perfused rat kidney

Exposure to whole body radiation is associated with prompt changes in urinary excretion of prostaglandins. We investigated the separate effects of radiation on rat kidney capillary and tubular system prostaglandin synthesis. Animals were irradiated to the left kidney area with a single dose of 15 Gy. One week later the rats were anesthesized, the renal artery, vein and ureter of the left kidney cannulated, and the kidney removed and perfused with Krebs-Henseleit physiological buffer at a rate of 10-12 ml/min. Effluent fluids were collected separately from the renal vein and from the ureter of irradiated and control (operated sham-irradiated animals) and were assayed by radioimmunoassays for thromboxane A2 (TXB2) and prostacyclin (6 keto PGF1 alpha). Histological examination of the irradiated kidneys showed no significant changes, and electron microscopy revealed minimal interstitial edema. In contrast to these minimal changes, TXB2 assays showed a significant increase both in the venous and ureter effluents. Following stimulation with angiotensin II in the perfusate, a further significant increase in TXB2 production was observed both by the capillary and the tubular systems. With 6 Keto PGF1 a slightly different response was seen. The basal production was increased only in the ureter effluent of the irradiated animals, while there were no changes in the release in the venous effluents. In parallel, radiation significantly increased the angiotensin II stimulated production capacity of prostacyclin by the tubular system. The response of the capillary system following irradiation may create imbalance between these two important substances and lead to the radiation effects in the renal tissue.