Studies on the changes in calcium fluxes in ts-RSV LA 90 cells transformation

To study the role of Ca2+ fluxes and Ca2+]i in cell transformation by the v-src gene, ts-RSV LA 90 cells was used in this experiment. Ca2+ fluxes across the plasma membrane was measured with radioisotopes. The relative Ca2+]i in LA 90 cells loaded Indo-1AM was measured by computer-based Optical Multichannel Analyzer connected with fluorescence microscopy. It was observed that changes in rate of Ca2+ fluxes across the plasma membrane are one of the earliest detectable changes of LA 90 cells transformation. Rates of Ca2+ fluxes in transformed LA 90 cells (40 degrees C) is higher than that in normal LA 90 cells (33 degrees C) and rates of Ca2+ fluxes increased in 25 minutes when LA 90 cells shifted from nonpermissive (40 degrees C) to permissive (33 degrees C) temperature. TMB-8 inhibited increases in rate of Ca2+ efflux induced by pp 60 v-src, and increase in rate of Ca2+ efflux in normal LA 90 cells was stimulated by calf serum. The rate of Ca2+ efflux was related to the changes in temperature. The increase in rate of Ca2+ influx induced by pp 60 v-src could be blocked by verapamil. The rate of Ca2+ influx was not affected by the changes in temperature. The increase in relative Ca2+]i induced by pp 60 v-src is one of the early events in the transformation process. The level of Ca2+]i in transformed LA 90 cells was about 2-3 times as much as that in normal LA 90 cells.(ABSTRACT TRUNCATED AT 250 WORDS)