T. Koyama et al., Involvement of Rho-kinase and tyrosine kinase in hypotonic stress-induced ATP release in bovine aortic endothelial cells, J PHYSL LON, 532(3), 2001, pp. 759-769
1. Hypotonic stress induces ATP release followed by Ca2+ oscillations in bo
vine aortic endothelial cells (BAECs). We have investigated the cellular me
chanism of the hypotonic stress-induced ATP release.
2. Hypotonic stress induced tyrosine phosphorylation of at least two protei
ns, of 110 and 150 kDa. Inhibition of tyrosine kinase by the tyrosine kinas
e inhibitors herbimycin A and tyrphostin 46 prevented ATP release and ATP-m
ediated Ca2+ oscillations induced by hypotonic stress.
3. ATP release was also inhibited by the pretreatment of the cells with bot
ulinum toxin C3, and augmented by lysophosphatidic acid. Furthermore, pre-t
reating the cells with Y-27632, a selective inhibitor of Rho-kinase, also s
uppressed the hypotonic stress-induced ATP release and Ca2+ oscillations, i
ndicating that Rho-mediated activation of Rho-kinase may be involved in the
hypotonic: ATP release.
4. Hypotonic stress also induced a transient rearrangement of the actin cyt
oskeleton, which was suppressed by the tyrosine kinase inhibitors Y-27632 a
nd cytochalasin B. However, pretreatment of the cell with cytochalasin B in
hibited neither the hypotonic stress-induced ATP release nor the Ca2+ oscil
lations.
5. These results indicate that tyrosine kinase and the Rho-Rho-kinase pathw
ays are involved in hypotonic stress-induced ATP release and actin rearrang
ement, but actin polymerization is not required for ATP release in BAECs.