Endotoxin increases intercellular resistance in microvascular endothelial cells by a tyrosine kinase pathway

Cap junction communication between microvascular endothelial cells has been proposed to contribute to the coordination of microvascular function. Sept ic shock may attenuate microvascular cell-to-cell communication. We hypothe sized that lipopolysaccharide (LPS) attenuates communication between microv ascular endothelial cells derived from rat hindlimb skeletal muscle. Endoth elial cells grown in monolayers expressed mRNA for connexin 37, 40, and 43. The expression of connexin 43 protein was confirmed, but connexin 40 prote in was not detected by immunocytochemistry or immunoblot analysis. Intercel lular resistance between cells of the monolayer, calculated using a Bessel function model, was increased from 3.3 to 5.3 M Omega by LPS. The effect wa s seen after 1 h of exposure and required a minimum concentration of 10 ng/ ml. Intercellular resistance returned to normal 1 h following removal of LP S. Neither the response to IFS, nor its reversal, was blocked by the protei n synthesis inhibitor cycloheximide (10 mu g/ml). Pretreatment of monolayer s with the tyrosine kinase inhibitors PP-2(10 nM), lavendustin-C (1 mu M), and geldanamycin (200 nM) prevented this LPS response; geldanamycin was als o able to reverse the response. Inhibitors of MAP kinases, PD 98059 (5 mu M ) and SE 202190 (5 mu M), and PKC (500 nM bisindolylmaleimide I) were unabl e to block the LPS response. We propose that LPS attenuates cell-to-cell co mmunication through a signaling pathway that is tyrosine kinase dependent. (C) 2000 Wiley-Liss, Inc.