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Contractile responses of cultured bovine retinal pericytes to angiotensin II
T Matsugi1, Q Chen, D R Anderson
1Department 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.