ISOMETRIC CONTRACTION BY FIBROBLASTS AND ENDOTHELIAL-CELLS IN TISSUE-CULTURE - A QUANTITATIVE STUDY

We have used an isometric force transducer to study contraction of two types of nonmuscle cells in tissue culture. This method permits the q uantitative measurement of contractile force generated by cells of def ined type under the influence of external agents while allowing detail ed morphological observation. Chick embryo fibroblasts (CEF), which fo rm a contractile network inside a collagen matrix, and human umbilical vein endothelial cells (HUVE), which are located in a monolayer on th e surface of the collagen matrix, were studied. CEF and HUVE in 10% FC S produce a substantial tension of 4.5 +/- 0.2 x 10(4) dynes/cm2 and 6 .1 x 10(4) dynes/cm2, respectively. Both cell types contract when stim ulated with thrombin, generating a force per cell cross-sectional area of approximately 10(5) dynes/cm2, a value approximately an order of m agnitude less than smooth muscle. The integrity of the actin cytoskele ton is essential for force generation, as disruption of actin microfil aments with cytochalasin D results in a rapid disappearance of force. Intact microtubules appear to reduce isometric force exerted by CEF, a s microtubule-disrupting drugs result in increased tension. Contractio n by HUVE precedes a dramatic rearrangement of actin microfilaments fr om a circumferential ring to stress fibers.