The Comparative Effects of Vinblastine and Dactinomycin on Regenerating Larval Rana Pipiens Tails

摘要

Because Vinblastine (VLB) has been effective in arresting certain mammalian cancers, particularly those associated with circulatory and muscular systems. A study was made to ascertain the effects of VLB on tail regeneration in five and ten day old Rana pipiens larvae. Fifty animals of each age level were immersed separately in 500ml of drug solution; concentrations used were 20, 10, 5, 2.5, 1.25 and 0.67 micrograms/ml plus a control group in spring water. Complete series (two age levels at the seven concentrations) were kept for four days at three different temperatures: 15, 20 and 25C. Parallel series with Actinomycin D, a potent antitumor chemotherapeutic, were used for comparison since its effects on regeneration have already been reported. Dactinomycin is 50 to 110% more effective in general inhibition; maximum effective dose for both drugs being c.10 micrograms/ml. Selective inhibition of neural and muscular regeneration was obtained with 10 and 20 micrograms/ml VLB only at 20C. Anomalous formation of new blood vessels was observed in larvae treated with 10 and 20 micrograms/ml VLB at both 15 and 20C. Instead of anastomosing into a fine vascular network, blood islands in the tail increased in size, the cells remaining tightly compacted in a solid mass with little cytoplasm evident. Under all experimental conditions but uncorrelated with specific ones, VLB produced loss of striation patterns and fiber separation in the central tail muscle. Despite the carcinostatic effects of regeneration and VLB an anomalous tuff of fibrous tissue was noted in one of the 4,200 experimental animals. (Author)