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Isolation of Retinal Arterioles for Ex Vivo Cell Physiology Studies
Published on: July 14, 2018
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Posterior Ciliary Artery Contraction by Bradykinin Receptor Subtypes and Implications for Retinal Blood Flow
Najam A Sharif1,2,3, Sunny E Ohia1, Madhura Kulkarni-Chitnis1
1Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Texas Southern University, Houston, TX 75207, USA.
Frontiers in Bioscience (Elite Edition)
|October 11, 2025
Summary
Bradykinin (BK) causes contractions in bovine posterior ciliary arteries via B1 and B2 receptors, potentially impacting retinal blood flow and contributing to glaucomatous optic neuropathy (GON). This research clarifies BK receptor function in ocular vessels.
Area of Science:
- Ocular physiology
- Pharmacology
- Ophthalmology
Background:
- Low retinal blood flow is a key risk factor for glaucomatous optic neuropathy (GON).
- Bradykinin (BK) influences smooth muscle contraction, and its receptors are present in ocular tissues.
- The precise function of BK receptors in retinal blood vessels remains unclear.
Purpose of the Study:
- To pharmacologically characterize the contractile effects of BK and related agonists on isolated bovine posterior ciliary arteries (PCAs).
- To identify the specific BK receptor subtypes involved in PCA contraction.
Main Methods:
- Isolated bovine PCAs were used in an organ bath setup.
- Cumulative addition of BK and related peptide agonists was performed.
- Receptor-selective agonists and antagonists were employed to define BK receptor heterogeneity.
Main Results:
- All tested kinin peptides concentration-dependently contracted PCA rings.
- Both high-affinity (nM range) and low-affinity (μM range) receptor sites were identified.
- Contractions were modulated by B1- and B2-receptor selective antagonists, indicating the involvement of both subtypes.
Conclusions:
- Pharmacological data suggest the presence of both B1 and B2 BK receptors, and possibly other subtypes, mediating PCA contractions.
- These findings imply that BK receptor activation may narrow PCA diameters, reduce retinal blood flow, and contribute to GON.
- Understanding these mechanisms could inform future therapeutic strategies for preventing vision loss in GON.
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