Heat shock has been known to change cellular responses to noxious stimuli by inducing heat-shock proteins (Hsps). We hypothesized that a heat-shock response modulates cytokine production in murine aortic vascular smooth muscle cells (VSMCs). VSMCs were exposed to 44 degrees C for 15-60 min, and subjected to interleukin-1beta (IL-1beta) or tumor necrosis factor alpha (TNFalpha), which induced interleukin-6 (IL-6) production. Expression of Hsps was examined with immunoblots, immunocytochemistry, or enzyme-linked immunosorbent assay (ELISA), and that of IL-6 with reverse transcription-polymerase chain reaction (RT-PCR) or ELISA. Heat shock (44 degrees C for 45 min) induced Hsp72 in VSMCs at 4 h and elicited its maximal expression at 8 h after the end of heat shock. Treatment with IL-1beta increased IL-6 transcription in VSMCs up to 24 h in an incubation time-dependent manner. Treatment with IL-1beta or TNFalpha caused a concentration-dependent increase in IL-6 production in culture medium, which was attenuated by heat shock. Although treatment with Hsp72 or Hsp60 alone did not significantly affect basal IL-6 release into culture medium statistically, cotreatment with IL-1beta and Hsp72, but not Hsp60 or boiled Hsp72, decreased IL-1beta-induced IL-6 production in culture medium. Introduction of Hsp72, but not Hsp60, into VSMCs decreased IL-1beta-induced IL-6 production in culture medium. These results indicate that the heat-shock response transcriptionally attenuated production of IL-6 in murine aortic VSMCs.