Contractile responses of cultured bovine retinal pericytes to angiotensin II
T. Matsugi, Q. Chen and D. R. Anderson
Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami School of Medicine, Fla., USA.
OBJECTIVE: To document that angiotensin (ANG) II contracts cultured bovine
retinal pericytes via saralasin-sensitive receptors if the cells are
prerelaxed. METHODS: Changes in the contractile tone were quantified as the
changes in the summed length of wrinkles induced by pericytes cultured on
the silicone surface. RESULTS: Angiotensin II (10(-5) mol/L) did not
increase the contractile tone of cultured pericytes that were not
prerelaxed. However, when the pericytes had been prerelaxed 41% with
10(-6)-mol/L sodium nitroprusside, ANG II at the range of 10(-7) to 10(-5)
mol/L caused prompt, dose-related, significant (P<.01) contraction. It
induced a maximum contraction (29.9%+/-5.2% [mean+/-SE]) at 10(-6) mol/L.
This effect lasted at least 10 minutes. Angiotensin II receptor antagonist
saralasin (10(-6) mol/L) abolished the contractile effect of ANG II (10(-6)
mol/L), although by itself it did not affect the contractile tone.
CONCLUSIONS: Angiotensin II contracts cultured pericytes through
saralasin-sensitive ANG II receptors. If ANG II affects the contractile
tone of pericytes in vivo, it may affect capillary caliber, resistance, and
blood flow.
