Acute Effect of Dipyridamole on Urinary Prostaglandin Excretion

Prof. Irina Tareyeva, Laboratory of Nephrology, First Moscow Medical Setchenov Institute, 11-a Rossolino str., 119021 Moscow (USSR) Dear Sir, We were very interested in the paper by de Jong et al. [1] in which they suggested that the acute antiproteinuric effect of dipyridamole is due to an efferent vasodilation with a fall in intraglomerular capillary pressure. Among hypothetic mechanisms of intrarenal action of dipyridamole, the increase of prostacyclin biosynthesis has been discussed. We studied the acute effect of dipyridamole 20 mg i.v. on 1.5-hour urinary prostaglandins (PGE2, PGF2α) excretion and diuresis in 18 patients with biopsy-proven glom-erulonephritis. The patients had proteinuria of 1,1 ± 0,75 g/day (mean ± SD)‚a mean blood pressure of 117.6 ± 12,6 mm Hg, and a plasma creatinine concentration of 127 ± 29 μg/l. They were on a diet containing 85–120 mmol Na/ day and did not receive any drugs at least 5 days before investigation. At the beginning of the first and second periods or urine collection the patients drank 200 ml of water. Urinary PGE2 and PGF2α were measured using ‘clinical assays’ PGF2α RIA kits after amberlite XAD-2 column concentration, ethylacetate extraction and silicic acid column chromatography with registration of the percentage of the substance at the output. Standard and unknown samples containing PGE2 were processed with natriumborhydrid for conversion of PGE2 into PGF2α. After dipyridamole infusion PG excretion increased in 15 out of 18 patients (table 1). The rate of the increase of PG excretion after dipyridamole was positively correlated with the increase of diuresis (r = 0.68 and 0.48; p < 0.05) and did not correlate with blood pressure, plasma creatinine concentration and glomerular filtration rate which were measured before the investigation. Table 1. Effect of dipyridamole infusion 20 mg on PG excretion and diuresis in 18 patients with chronic glomerulonephritis (mean ± SD)