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Chronic thromboxane inhibition preserves function of rejecting rat renal allografts
T M Coffman1, P Ruiz, F Sanfilippo
1Department of Medicine, Duke University, VA Medical Center, Durham, North Carolina.
Abstract:
Increased production of thromboxane (TX) by rejecting renal allografts results in significant and partially reversible renal vasoconstriction. In this study, we evaluated the potential benefit of chronically administering the TX synthetase inhibitor OKY-046 from the time of transplantation in a rat model of acute renal allograft rejection. In animals which received 75 mg/kg/day of OKY-046 by intermittent i.p. injection, allograft function was not improved, but renal thromboxane production was not significantly inhibited. However, animals which received an equivalent dose of OKY-046 by continuous intra-arterial infusion for four days maintained clearances of inulin (4.46 +/- 0.79 ml/min/kg) and PAH (23.86 +/- 1.81 ml/min/kg) at normal levels not different from non-rejecting isografts (4.83 +/- 0.93 and 18.33 +/- 2.55 ml/min/kg, respectively). In contrast, animals which received continuous infusion of saline vehicle alone developed a significant reduction in renal function (CIn: 1.58 +/- 0.27 ml/min/kg; CPAH: 9.12 +/- 1.51 ml/min/kg) by the fourth day after transplantation. Intra-arterial infusion of OKY-046 significantly reduced four-day allograft TXB2 production, as well as urinary TXB2 excretion, but had no effect on allograft production of PGE2 or 6-keto-PGF1 alpha. Despite the beneficial effects on allograft function, OKY-046 neither altered the morphologic appearance of the cellular infiltrate nor the systemic proliferative and cytotoxic anti-donor cellular immune responses. Six days following transplantation, renal TXB2 production was only partially inhibited in animals given continuous infusions of OKY-046, and remained markedly elevated. This partial inhibition of TX production resulted in a slight but insignificant functional improvement.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Continuous intra-arterial infusion of a thromboxane synthetase inhibitor improved renal allograft function in rats by reducing thromboxane production. Intermittent injections were ineffective, highlighting the importance of delivery method for this renal transplant therapy.
Area of Science:
- Nephrology
- Immunology
- Pharmacology
Background:
- Rejection of renal allografts increases thromboxane (TX) production, leading to renal vasoconstriction.
- TX synthetase inhibitors may mitigate this effect, but optimal administration is unclear.
Purpose of the Study:
- To evaluate the efficacy of chronic administration of the TX synthetase inhibitor OKY-046 in a rat model of acute renal allograft rejection.
- To compare the effects of intermittent injections versus continuous intra-arterial infusion of OKY-046 on allograft function and TX production.
Main Methods:
- Rats received OKY-046 via intermittent intraperitoneal injection or continuous intra-arterial infusion.
- Allograft function was assessed by measuring clearances of inulin and PAH.
- Renal and urinary TXB2, PGE2, and 6-keto-PGF1 alpha levels were measured.
Main Results:
- Continuous intra-arterial infusion of OKY-046 maintained normal renal function and significantly reduced allograft TXB2 production.
- Intermittent injections did not improve allograft function or significantly inhibit TX production.
- OKY-046 did not alter cellular infiltrate morphology or systemic immune responses.
Conclusions:
- Continuous intra-arterial infusion of OKY-046 effectively preserves renal allograft function during acute rejection by inhibiting TX production.
- The route of administration is critical for the therapeutic efficacy of TX synthetase inhibitors in renal transplantation.
- Further investigation is needed to optimize TX inhibition for sustained functional improvement.