1999 · Ishikawa — A preventive effect of a selective endothelin-A receptor antagonist, S-0139, on the erythropoietin-induced reduction of the renal cortical blood flow.
Super-Abstract
This animal study in Wistar rats shows that erythropoietin (EPO) reduces renal cortical blood flow (RCBF) by triggering endothelin-1 release, and that the selective ET-A receptor antagonist S-0139 can prevent this reduction. Molecular hydrogen gas was used purely as a measurement tool (hydrogen gas clearance method), not as a therapeutic intervention. (Urological Research, 1999.)
Commentary
This study investigates a side effect of erythropoietin therapy — a significant reduction in renal cortical blood flow — and tests whether blocking the endothelin-A receptor can prevent it. The hydrogen gas clearance method, a classic technique for measuring tissue blood flow, was used to quantify RCBF. In this context, a small amount of H₂ gas is dissolved in saline and injected locally; the rate at which it is cleared from the tissue is proportional to blood flow. H₂ here is a diagnostic tracer, not a therapeutic agent. The pharmacological finding about S-0139 and ET-A antagonism is the scientific contribution of this paper.
Key quotes
- „The reduction of RCBF is due to ET(1)-derived vasoconstriction. S-0139 has potential for preventing EPO-induced and ET(1)-mediated RCBF reduction.“ — main conclusion: endothelin mediates EPO-induced renal vasoconstriction; ET-A blockade prevents it
- „The RCBF was measured every 30 min by the hydrogen gas clearance method.“ — H₂ used as measurement tool only — not as therapeutic agent
- „EPO induces ET(1) secretion. The reduction of RCBF is due to ET(1)-derived vasoconstriction.“ — mechanism: EPO → endothelin-1 → vasoconstriction → reduced renal blood flow
Our assessment
This is an animal pharmacology study (rat model) — it is not a therapeutic H₂ study. Molecular hydrogen was used exclusively as a measurement tool (clearance method) to quantify renal blood flow. The therapeutic subject is endothelin-A receptor antagonism, not H₂. Results cannot be extrapolated to humans without further clinical validation. The renal blood flow finding is of interest for nephrology and EPO therapy management, but provides no evidence for H₂ health effects.
Study design
- Type: animal study · Model: male Wistar rats (10 weeks, ~250 g), n = 5 per group (5 groups) · Intervention: EPO (200 or 400 U/kg/h IV) ± ET-A antagonist S-0139 (4 or 40 mg/kg/h IV)
- H₂ role: hydrogen gas clearance method used as blood-flow measurement tool only · Result: EPO significantly reduced RCBF and raised ET-1; S-0139 co-administration prevented RCBF reduction without affecting creatinine or renin activity
Abstract
We have confirmed that renal cortical blood flow (RCBF) is significantly decreased by recombinant human erythropoietin (EPO). Endothelin-1 (ET(1)) is thought to be a mediator because its level increased significantly when EPO was administered. The present study was performed to clarify the effect of a selective ET-A receptor antagonist, S-0139, on EPO-induced RCBF reduction. Ten-week-old male Wistar rats, weighing about 250 g, were divided into five groups. Group 1 (n = 5), a control group, received normal saline solution (NSS). Group 2 (n = 5) received 200 U/kg body weight (BW) per hour of EPO. Group 3 (n = 5) received 400 U/kg BW per hour of EPO. Group 4 (n = 5) received both 200 U/kg BW per hour of EPO and 4 mg/kg BW per hour of S-0139. Group 5 (n = 5) received both 200 U/kg BW per hour of EPO and 40 mg/kg BW per hour of S-0139. Drugs were administered intravenously via the right femoral vein using a microinfusion pump for 4 h under urethane anesthesia. The RCBF was measured every 30 min by the hydrogen gas clearance method. When the 4 h had elapsed, the concentrations of plasma creatinine (Cr), ET1 and renin activity (RA) were measured. Compared with group 1, groups 2 and 3 showed significant (P < 0.001) decreases of RCBF, while the ET1 levels of these two groups increased significantly (P < 0.03). The ET1 of groups 4 and 5 also increased significantly (P < 0.03), however, the RCBF of these two groups did not decrease. No significant differences were observed in either Cr or RA between the five groups. EPO induces ET(1) secretion. The reduction of RCBF is due to ET(1)-derived vasoconstriction. S-0139 has potential for preventing EPO-induced and ET(1)-mediated RCBF reduction.
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