s-145 and Proteinuria

1. Several lines of evidence indicate that thromboxane (Tx) A2 may contribute to the development and maintenance of hypertension. The present study was undertaken to evaluate the role of TxA2 in the development of hypertension in spontaneously hypertensive rats (SHR) by using an orally active, highly specific TxA2/prostaglandin H2 receptor antagonist S-1452. 2. Vehicle (1% arabic gum solution) alone was given orally to Wistar-Kyoto (WKY) rats (n = 15) and SHR (n = 14), while S-1452 (10 mg/kg per day, twice daily) was administered orally to SHR (n = 16) for 18 weeks (from 5 to 23 weeks of age). 3. No significant difference was observed in tail-cuff blood pressure (BP) between vehicle- and S-1452-treated SHR before and at 5 and 11 weeks after treatment. Thereafter, BP was further elevated in vehicle-treated SHR, but was significantly blunted in SHR treated with S-1452 at 15 (224+/-8 vs 211+/-13 mmHg; P < 0.01) and 18 weeks (227+/-9 vs 206+/-10 mmHg; P < 0.001); this was associated with reduced proteinuria. 4. Urinary TxB2 in vehicle-treated SHR, especially during the early period, was significantly greater than that in WKY rats, while no significant difference was observed in urinary 6-ketoprostaglandin F1alpha (6-keto-PGF1alpha) between the two groups. Treatment with S-1452 reduced urinary excretion of TxB2 at 18 weeks. 5. The present study shows that S-1452, at the dose used, does not reduce BP during the early period of the development of hypertension. These results suggest that the role of enhanced TxA2 production in the development of hypertension is small, if any, in SHR. Delayed response of BP may be independent of the direct pharmacological effects of S-1452.

Topics: 6-Ketoprostaglandin F1 alpha; Aldosterone; Animals; Antihypertensive Agents; Blood Pressure; Bridged Bicyclo Compounds; Dinoprostone; Fatty Acids, Monounsaturated; Hypertension; Male; Potassium; Prostaglandin Antagonists; Prostaglandins; Prostaglandins H; Proteinuria; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Receptors, Prostaglandin; Receptors, Thromboxane; Renin; Sodium; Thromboxane B2; Time Factors

To clarify the role of thromboxane A2 (TxA2), endothelin-1 (ET-1) and endothelin-3 (ET-3) in the progression of glomerular injury in accelerated nephrotoxic serum nephritis (NTN) in the rat, we studied the expression of ET-1 and ET-3 at the kidney by immunohistochemical method and examined the effect of a novel TxA2 receptor antagonist, S-1452. The S-1452-treated group showed significantly lowered 24-hr proteinuria and milder glomerular cell proliferation and lobulation than the non-treated group (NT group) on experimental day 10. There was no significant difference in the glomerular polymorphonuclear cell (PMN) exudation between the 2 groups. Immunofluorescent findings revealed that ET-1 and ET-3 were seen along the glomerular capillary wall and partly in the mesangial area in all rats of the NTN group. The degree and positive rate of ET-1 and ET-3 staining were significantly higher in the NTN group than in the S-1452 group. These findings suggest that TxA2 may be an important mediator in the development of NTN, and that TxA2 receptor antagonist may be useful for the reduction of glomerular injury in this type of nephritis. In addition, local production of ET may contribute to the development of this nephritis.

Topics: Animals; Bridged Bicyclo Compounds; Chromium; Endothelin-1; Endothelin-3; Fatty Acids, Monounsaturated; Immunohistochemistry; Kidney Glomerulus; Male; Microscopy, Fluorescence; Nephritis; Prostaglandin Antagonists; Proteinuria; Rabbits; Rats; Rats, Wistar; Receptors, Thromboxane; Sodium; Thromboxane A2

To shed light on the role of thromboxane A2 (TXA2) in renal injury, we evaluated the effects of S-1452, a TXA2 receptor antagonist, on rats with streptozotocin (STZ)-induced diabetic nephropathy and murine lupus nephritis. In STZ diabetes rats (n = 6), urinary protein excretion significantly increased from 8 weeks and was about 5 times as much as that in normal rats at 10 weeks after induction of diabetes. In S-1452-treated rats (n = 6), increase in urinary protein was rarely observed and was significantly inhibited at 8 and 10 weeks after induction of diabetes. In (NZB x NZW)F1 mice, no proteinuria was detected in vehicle controls (n = 20) and S-1452-treated mice (n = 20) from 0 to 8 weeks after initiation of S-1452 treatment. Proteinuria was observed in 3, 7 and 8 mice in the control group, and 0, 2 and 5 mice in the S-1452 group at 12, 16 and 20 weeks after initiation of S-1452 treatment, respectively. Proteinuria developed more slowly in S-1452-treated mice than in vehicle controls. In conclusion, TXA2 receptor antagonist, S-1452, suppresses the progression of renal injury.

Topics: Acetylglucosaminidase; Animals; Blood Glucose; Bridged Bicyclo Compounds; Cholesterol; Creatinine; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Fatty Acids, Monounsaturated; Female; Lupus Nephritis; Male; Mice; Mice, Inbred NZB; Proteinuria; Rats; Rats, Wistar; Receptors, Thromboxane