This study examines the real time intracellular calcium concentration,
[Ca2+](i), response of canine medial collateral ligament (MCL) and an
terior cruciate ligament (ACL) fibroblasts subjected to a fluid-induce
d shear stress of 25 dynes/cm2(.) In experiments using a modified Hank
s' Balanced Salt Solution (HBSS) perfusate, both cell types demonstrat
ed a significant increase in peak [Ca2+](i) compared to respective no-
flow controls, the response of MCL fibroblasts being nearly 2-fold gre
ater than that of ACL fibroblasts. In studies where the cells were bat
hed in a medium of HBSS supplemented with 2% newborn bovine serum (NBS
) and then introduced to flow with the same medium, ACL fibroblasts re
sponded nearly 3-fold greater than MCL fibroblasts. Neomycin (10 mM),
thapsigarigin (1 mu M) and Ca2+-free media supplemented with EGTA (1 m
M) were able to inhibit significantly the [Ca2+](i) response to flow w
ith HBSS in both fibroblasts. Thapsigargin also blocked the NBS flow r
esponse in both cell types, while neomycin and Ca2+-free media signifi
cantly inhibited the ACL response. Our findings demonstrate that ACL a
nd MCL cells are not the same. These differences may be related to the
disparate healing capacity of the ACL and MCL observed clinically. (C
) 1997 Elsevier Science Inc.