Key result
Angiotensin II and vasoactive intestinal peptide specifically bind to cultured bovine retinal pericytes, with Ang II inducing pericyte contraction and minimal cAMP synthesis.
Bovine retinal pericytes possess receptors for vasoactive peptides and contract in response to Angiotensin II, suggesting a potential role in regulating capillary resistance.
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Does not yet inform retinal microvascular therapy; hypothesis-generating for pericyte Ang II responses in animals.
To test the potential for vasoactive neuropeptide receptors to affect capillary resistance, we have begun to study the plausibility that pericytes might be equipped to respond to a representative peptide vasoconstrictor and a representative peptide vasodilator. Pericytes cultured from the bovine retinal vasculature specifically bind the angiotensin II (Ang II) antagonist saralasin (1 nM125I-saralasin bound at 2.2 +/- 0.41 fmol/mg protein) and 125I-vasoactive intestinal peptide (VIP; Kd of 0.5 nM with a population of 30 fmol/mg protein). Incubation with 100 microM Ang II induced minimal cAMP synthesis, while VIP (1 microM, 10 microM) did not induce any change in cAMP concentration. Ang II (10 microM and 100 microM) caused contraction of pericytes cultured on an elastic silicone surface. Circulating or locally produced vasoactive neuropeptides might affect pericyte contractile tone via several intracellular pathways, moderated by indirect effects of these peptides through endothelial stimulation, with the net effect on local blood flow resulting from the effects on arteries and veins as well as capillaries.
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Ferrari-Dileo et al. (2010) studied Glaucoma. Angiotensin II and Vasoactive Intestinal Peptide was evaluated on Peptide hormone binding, cAMP synthesis, and pericyte contraction. Angiotensin II and vasoactive intestinal peptide specifically bind to cultured bovine retinal pericytes, with Ang II inducing pericyte contraction and minimal cAMP synthesis.
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