Abstract
Verapamil had previously been shown to increase cellular melphalan uptake and cytotoxicity in fibrosarcomas, and increased the area under the blood concentration versus time curve (AUC) for melphalan in CBA mice. Verapamil (10 mg kg-1 i.p.) had no effect on the fractional distribution of cardiac output (FDCO), measured with 86Rb-rubidium chloride, to subcutaneous fibrosarcomas. 14C-Melphalan uptake by FS13 fibrosarcomas was increased 60 min after verapamil (10 mg kg-1 i.p.), but not after lower doses which did not affect the AUC. Flunarizine (5 mg kg-1 i.p.) also had no effect on FDCO to FS13 fibrosarcomas, and tended to increase 14C-melphalan content of blood and the fibrosarcomas and to promote growth delay by melphalan. Alcohol increased FDCO to FS13 fibrosarcomas, maximally at a 1:20 dilution in saline, but had no effect on 14C-melphalan uptake or growth delay. Thus, melphalan cytotoxicity correlated with tumour melphalan uptake, and both followed changes in the AUC for melphalan but not changes in FDCO. In these murine fibrosarcomas melphalan uptake and cytotoxicity were not limited by blood flow. In subcutaneous human melanoma HX46 xenografts, verapamil had no effect on the FDCO, nor on 14C-melphalan uptake, and did not affect blood 14C-melphalan levels, suggesting absence of effects on the AUC and on cellular uptake. Alcohol did not increase the FDCO to HX46 xenografts, providing evidence for a different vascular supply.
Highlights
Male and female CBA/ca mice were maintained in the Institute of Cancer Research (ICR) and used when at least 12 weeks old, weight 20g and 25-30 g
The fractional distribution of cardiac output (FDCO) to the fibrosarcomas decreased with increase in weight, as demonstrated for FS13 in Figure 1, which shows the data as mean values for control tumours from 24 experiments
Blood pressure would have been the best guide to dose of verapamil, but could not be measured in unanaesthetised mice
Summary
Male and female CBA/ca mice were maintained in the Institute of Cancer Research (ICR) and used when at least 12 weeks old, weight 20g (females) and 25-30 g (males). Eccles (ICR) were passaged every 2-3 weeks in female CBA mice. Most experiments used bilateral FS13 fibrosarcomas, passages 5-12, at 2 weeks, but some used FS12 (passages 12-15). 608 B.A. ROBINSON et al., The human melanoma HX46 xenograft was implanted as 1-2mm pieces subcutaneously in male CBA mice, immunosuppressed by thymectomy and 9 Gy total body irradiation from a 60Co-cobalt source, preceded 48 h by cytosine arabinoside 200mgkg-1 by i.p. injection (Millar et al, 1978a; Steel et al, 1978). Passages 5-7 were used, 3 weeks after implantation, a human karyotype demonstrated through passage 7 (Selby et al, 1980)
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