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 organ after, for instance, ischemia. However, the possible role of the extracellular matrix on these effects has thereby been neglected. The recently developed model system of neonatal heart cells cultured on a collagen gel, characterized by a high coherence of contractions, has been used to study the effects of this more in vivo-like collagen environment on the heat shock response of the myocytes as compared to 'normally used' monolayer cultures. After four days differences were found in the heat-induced synthesis of HSPs of cells grown by the two culturing 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 basic level of synthesis as well as the heat-induced synthesis of HSP84 and HSP100 was decreased, for HSP60 both were increased, and for HSP70 no differences were found compared to the monolayer cultures. Our results suggests that the collagen matrix has a regulatory role in the synthesis of HSPs.