The novel immunosuppressant SDZ-RAD protects rat brain slices from cyclosporine-induced reduction of high-energy phosphates.
Br J Pharmacol 2000;
129:485-92. [PMID:
10711346 PMCID:
PMC1571863 DOI:
10.1038/sj.bjp.0703079]
[Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/1999] [Revised: 10/22/1999] [Accepted: 11/04/1999] [Indexed: 11/09/2022] Open
Abstract
1. SDZ-RAD, 40-O-(2-hydroxyethyl)-rapamycin, is a novel macrolide immunosuppressant. Because of its synergistic interaction, SDZ-RAD is under clinical investigation as immunosuppressant in combination with cyclosporine after organ transplantation. Neurotoxicity is a critical side-effect of cyclosporine. 2. We studied the effect of SDZ-RAD and its combination with cyclosporine on high-energy phosphates, phosphocreatine (PCr) and nucleoside triphosphates (NTP), in brain slices using 31P-magnetic resonance spectroscopy (MRS). 3. Cyclosporine significantly reduced high-energy phosphates after 2 h in a dose-dependent manner (100 micrograms l-1: 93 +/- 3% of control (NTP), 91 +/- 3% (PCr); 500 micrograms l-1: 84 +/- 2% (NTP), 73 +/- 2 (PCr); 5000 micrograms l-1: 68 +/- 3% (NTP), 55 +/- 5% (PCr); n = 6; P < 0.02). 4. In contrast, after perfusion for 2 h, SDZ-RAD (500 micrograms l-1 and 5000 micrograms l-1) significantly increased high-energy phosphate concentrations in the brain slices (P < 0.02). Even at the lowest concentration, SDZ-RAD protected brain energy metabolism against cyclosporine toxicity: 100 micrograms l-1 SDZ-RAD + 5000 micrograms l-1 cyclosporine: 86 +/- 3% (NTP), 83 +/- 7% (PCr), n = 3, P < 0.03 compared to cyclosporine alone. 5. As evaluated using an algorithm based on Loewe isobolograms, the effects of SDZ-RAD/cyclosporine combinations on brain energy reduction were antagonistic. Both drugs were found in mitochondria using h.p.l.c-MS analysis. 6. We conclude that cyclosporine inhibits mitochondrial high-energy phosphate metabolism, which can be antagonized by SDZ-RAD.
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