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Thermosensitization induced by pretreatment at supra- and subnormal temperatures, rate of protein synthesis and expression of the major heat shock proteins under such conditions was investigated in relation to intrinsic heat sensitivity of rat hepatoma cells, i.e. Reuber H35 and HTC. The high degree of heat susceptibility of H35 cells was reflected by a high degree of thermosensitization after pretreatment by heat (step-down heating) at temperatures of 42-44 degrees C for 30 min or cold for 16 h at temperatures ranging from 0 to 25 degrees C. Sensitization under step-down heating conditions was found to be paralleled by a delayed recovery of protein synthesis. Despite an increased relative rate, enhancement of the absolute rate of synthesis of the major heat shock proteins, HSP28, HSP60, HSP68, HSP70, HSP84 and HSP100, was less pronounced during step-down exposure. Comparable results were obtained during recovery of sensitized H35 cells at 37 degrees C after exposure to heat following pretreatment at 0 degrees C. Furthermore, clear differences in the regulation of the specific HSP synthesis, depending on the particular treatment protocol, were observed.

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The fibroblast populated collagen lattice was used to study the influence of extracts from roots or herbal parts of Echinacea purpurea on the collagen contracting abTty of C3H10n/2 mouse fibroblasts. Collagen gel contraction was inhibited by herb and root extracts which were added at the time of preparation of the gel. Inhibition was dependent on the amount of extract, the initial cell density and the collagen concentration used for preparation of the gel. When cell density was increased or collagen concentration decreased, the resulting increase in contraction counteracts the inhibitory effect of root extracts strongly, and that of herb extracts to a much lesser extent. The addition of extracts 1 h atter preparation of the gel could hardly prevent contraction. Echinacea extracts inhibited the cell morphological changes which are characteristic for fibroblasts contracting a collagen gel. The inhibition of morphological changes parallels the inhibition of collagen gel contraction in many respects. The significance of these observations is discussed in relation to the process of wound healing.