HSP SYNTHESIS OF NEONATAL RAT-HEART MYOCYTES IS REGULATED BY A COLLAGEN ENVIRONMENT

Studies on the stress response of isolated myocytes have gained great importance in the understanding of the response of the heart as an org an after, for instance, ischemia. However, the possible role of the ex tracellular matrix on these effects has thereby been neglected. The re cently developed model system of neonatal heart cells cultured on a co llagen gel, characterized by a high coherence of contractions, has bee n used to study the effects of this more in vivo-like collagen environ ment on the heat shock response of the myocytes as compared to 'normal ly used' monolayer cultures. After four days differences were found in the heat-induced synthesis of HSPs of cells grown by the two culturin g procedures. The degree of induction of different HSPs appeared to be directly related to the basic level of synthesis of these HSPs under the used culturing conditions. In collagen gel-grown cultures the basi c level of synthesis as well as the heat-induced synthesis of HSP84 an d HSP100 was decreased, for HSP60 both were increased, and for HSP70 n o differences were found compared to the monolayer cultures. Our resul ts suggests that the collagen matrix has a regulatory role in the synt hesis of HSPs.