These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Local action of the renin angiotensin system in the porcine ophthalmic circulation: effects of ACE-inhibitors and angiotensin receptor antagonists.
    Author: Meyer P, Flammer J, Lüscher TF.
    Journal: Invest Ophthalmol Vis Sci; 1995 Mar; 36(3):555-62. PubMed ID: 7890486.
    Abstract:
    PURPOSE: The renin angiotensin system and endothelium-derived substances are important regulators of the microcirculation. The authors studied the roles of angiotensins (Ang), angiotensin converting enzyme (ACE)-inhibitors, and Ang II-receptor antagonists in the porcine ophthalmic circulation. METHODS: Isolated porcine ciliary arteries were studied in myographs and the intact porcine eye in a perfusion system at 80 cm H2O perfusion pressure with Krebs-ringer bicarbonate solution (37 degrees C, 95% O2, 5% CO2). RESULTS: ACE-inhibitors enalaprilat and benazepril (both 10(-5) M) did not change ciliary vascular tone nor flow of perfused porcine eyes. However, enalaprilat or benazepril enhanced the relaxation of ciliary arteries to bradykinin (P < 0.02). In the perfused porcine eye, enalaprilat (10(-5) M) augmented vasodilation to bradykinin (P < 0.02). The bradykinin antagonist Hoe 140 (3 x 10(-7) M) prevented the relaxation of ciliary arteries to bradykinin (P < 0.001), but not to acetylcholine. In perfused eyes, Hoe 140 reduced the vasodilation to bradykinin (P < 0.01). Ang II (10(-8) to 10(-6) M) evoked a contraction of ciliary arteries and was more potent than Ang I. Enalaprilat abolished the effect of Ang I. The AT1-receptor antagonist, valsartan (10(-9) to 10(-5) M; 30 minutes) inhibited the response of ciliary arteries to Ang II, whereas the AT2-receptor ligand CGP 42112 B (10(-7) to 10(-8) M) was ineffective. In the perfused porcine eye, valsartan restored the decrease in flow to Ang II. CONCLUSIONS: Angiotensins play an important regulatory role in the porcine ophthalmic microcirculation through AT1-receptors. ACE-inhibitors prevents the effects of Ang 1 and augment endothelium-dependent relaxation to bradykinin, which releases nitric oxide through B2 receptors.
    [Abstract] [Full Text] [Related] [New Search]