Document Detail

Local action of the renin angiotensin system in the porcine ophthalmic circulation: effects of ACE-inhibitors and angiotensin receptor antagonists.
MedLine Citation:
PMID:  7890486     Owner:  NLM     Status:  MEDLINE    
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.
P Meyer; J Flammer; T F L?scher
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Investigative ophthalmology & visual science     Volume:  36     ISSN:  0146-0404     ISO Abbreviation:  Invest. Ophthalmol. Vis. Sci.     Publication Date:  1995 Mar 
Date Detail:
Created Date:  1995-04-17     Completed Date:  1995-04-17     Revised Date:  2010-03-24    
Medline Journal Info:
Nlm Unique ID:  7703701     Medline TA:  Invest Ophthalmol Vis Sci     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  555-62     Citation Subset:  IM    
Department of Ophthalmology, University Hospital, Basel, Switzerland.
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MeSH Terms
Angiotensin I / pharmacology*
Angiotensin II / pharmacology*
Angiotensin-Converting Enzyme Inhibitors / pharmacology*
Ciliary Body / blood supply
Endothelium, Vascular / physiology
Eye / blood supply*
Microcirculation / physiology
Muscle Relaxation / drug effects,  physiology
Muscle, Smooth, Vascular / drug effects,  physiology
Receptors, Angiotensin / antagonists & inhibitors*
Regional Blood Flow
Renin-Angiotensin System / physiology*
Vasodilation / drug effects
Reg. No./Substance:
0/Angiotensin-Converting Enzyme Inhibitors; 0/Receptors, Angiotensin; 11128-99-7/Angiotensin II; 9041-90-1/Angiotensin I

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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