An In Vitro Assay for Growth-Inhibiting Activity of Vinblastine2

Summary

An in vitro assay has been developed for the growth-inhibiting activity of vinblastine (VLB), based on a reduction in the multiplication of Earle's L cells produced by 1 to 16 × 10⁻⁹ g VLB per ml. Results were expressed in growth-inhibiting units (GIU), defined as that activity which decreased cell growth by 50 percent over a 16-hour period (the doubling time for controls). The assay was used to measure the activity in the serum of mice given intraperitoneal injections of VLB. Serum activity (in GIU/ml) was given as G(D,t) = 20 De^−0.2 for doses, D, from about 10 to 100 mg per kg and for times, t, from 1 to 10 hours following the injection.

2

Supported by a grant from the National Cancer Institute of Canada.

Author notes

3

Supported by a Province of Ontario Graduate Fellowship.