Summary
Little is known of the pharmacology of rhodamine 123 (RH-123), an agent reported to have carcinoma-selective experimental antitumor activity. Accordingly, using a high-performance liquid chromatographic assay system with fluorescence detection, we examined the plasma decay and the biliary and urinary elimination of parent drug and metabolites in female Sprague-Dawley rats receiving RH-123 at an intravenous dose (5 mg/kg) equivalent to the therapeutic dose used in murine tumor models. Following drug administration to unconscious animals, plasma levels of drug-associated fluorescence fell in a triphasic manner (t1/2α, 15 min; t1/2β, 1 h; t1/2γ, 4.7 h). In plasma, unchanged drug predominated but lower levels of the deacylated metabolite rhodamine 110 (RH-110) and two unknowns were also detectable throughout the study. Drug fluorescence was recovered extensively in both urine and bile. In unconscious animals with ureteral cannulae, urinary excretion (11.4% of the dose in 6 h) occurred predominantly as unchanged RH-123 (97% of the total), with low levels of RH-110 (2.4%) and two unknowns (<0.6% combined) also being present. Similarly dosed conscious animals (without surgical intervention) housed in metabolic cages showed a comparable pattern of urinary excretion, with 11.9% of the drug dose being recovered in 6 h and 21.9%, by 48 h. Biliary drug elimination accounted for 8% of the delivered dose in 6 h in unconscious animals and for 11% by 36 h in conscious animals fitted with biliary cannulae. In contrast to urinary excretion, in which unchanged drug predominated, only 50% of the fluorescence recovered in bile was attributable to RH-123. The remainder was due to a number of products that were detectable throughout the study. Of these, one present at significant levels was identified as a glucuronide conjugate of RH-123, based on the liberation of parent drug when the purified metabolite was incubated with β-glucuronidase or hydrolyzed with 1 N hydrochloric acid. Further studies with a radiolabeled form of RH-123 are necessary to establish the identity of the remaining unknowns disclosed in this work.
Similar content being viewed by others
References
Banes AJ, Link GW, Beckman WC Jr, Camps JL, Powers SK (1986) High performance liquid chromatographic quantitation of rhodamine 123 and 110 from tisues and cultured cells. J Chromatogr 356: 301–309
Bernal SD, Lampidis TJ, Summerhayes IC, Chen LB (1982) Rhodamine-123 selectively reduces clonal growth of carcinoma cells in vitro. Science 218: 1117–1118
Bernal SD, Lampidis TJ, McIsaac RM, Chen LB (1983) Anticancer activity in vivo of rhodamine 123, a mitochondrial-specific dye. Science 222: 169–172
Castro DJ, Saxton RE, Fetterman HR, Castro DJ, Ward PH (1987) Rhodamine-123 as a new photochemosensitizing agent with the argon laser: “nonthermal” and thermal effects on human squamous carcinoma cells in vitro. Laryngoscope 97: 554–561
Gear AR (1974) Rhodamine 6G, a potent inhibitor of mitochondrial oxidative phosphorylation. J Biol Chem 249: 3628–3637
Gupta RS, Dudani AK (1987) Species-specific differences in the toxicity of rhodamine 123 towards cultured mammalian cells. J Cell Physiol 130: 321–327
Herr HW, Huffman JL, Huryk R, Heston WD, Melamed MR, Whitmore WF Jr (1988) Anticarcinoma activity of rhodamine 123 against a murine renal adenocarcinoma. Cancer Res 48: 2061–2063
Higuti T, Niimi S, Saito R, Nakasima S, Ohe T, Tani L, Yoshimura T (1980) Rhodamine G, inhibitor of both H+-ejections from mitochondria energized with ATP and with respiratory substrates. Biochim Biophys Acta 593: 463–467
Johnson LV, Walsh ML, Bockus BJ, Chen LB (1981) Monitoring of relative mitochondrial membrane potential in living cells by fluorescence microscopy. J Cell Biol 88: 526–535
Krag DN, Theon AP, Gan L (1990) Hyperthermic enhancement of rhodamine 123 cytotoxicity in B16 mouse melanoma cells in vitro. Cancer Res 50: 2385–2389
Lampidis TJ, Salet C, Moreno G, Chen LB (1984) Effects of the mitochondrial probe rhodamine 123 and related analogs on the function and viability of pulsating myocardial cells in culture. Agents Actions 14: 751–757
Modica-Napolitano JS, aprille JR (1987) Basis for the selective cytotoxicity of rhodamine 123. Cancer Res 47: 4361–4365
Nadakavukaren KK, Nadakavukaren JJ, Chen LB (1985) Increased rhodamine 123 uptake by carcinoma cells. Cancer Res 45: 6093–6099
Ranganathan S, Hood RD (1989) Effects of in vivo and in vitro exposure to rhodamine dyes on mitochondrial function of mouse embryos. Teratogenesis Carcinog Mutagen 9: 29–37
Ranganathan S, Churchill PF, Hood RD (1989) Inhibition of mitochondrial respiration by cationic rhodamines as a possible teratogenicity mechanism. Toxicol Appl Pharmacol 99: 81–89
Shea CR, Chen N, Hasan T (1989) Dynamic aspects of rhodamine dye photosensitization in vitro with an argon-ion laser. Lasers Surg Med 9: 83–89
Summerhayes IC, Lampidis TJ, Bernal SD, Nadakavukaren JJ, Nadakavukaren KK, Shepherd EL, Chen LB (1982) Unusual retention of rhodamine 123 by mitochondria in muscle and carcinoma cells. Proc Natl Acad Sci USA 79: 5292–5296
Sweatman TW, Larussa RI, Israel M (1986) Systemic absorption of rhodamine 123 following instillation into rat urinary bladders. Abstracts, 14th International Cancer Congress, Budapest, Hungary, August 21–27, 1986, vol. 3. Akademiai Kiado, Budapest, p 944
Sweatman TW, Larussa RI, Seshadri R, Israel M (1987) An analytical system for the detection and quantitation of rhodamine-123 in biological samples. J Liquid Chromatogr 10: 1417–1429
Author information
Authors and Affiliations
Additional information
This work was supported in part by research grants CA 44890 (T.W.S.) and CA 37082 (M.I.) from the National Cancer Institute, National Institutes of Health, United States Public Health Service
Rights and permissions
About this article
Cite this article
Sweatman, T.W., Seshadri, R. & Israel, M. Metabolism and elimination of rhodamine 123 in the rat. Cancer Chemother. Pharmacol. 27, 205–210 (1990). https://doi.org/10.1007/BF00685714
Issue Date:
DOI: https://doi.org/10.1007/BF00685714