Contractile and relaxing effects of arachidonic acid derivatives on isolated bovine retinal resistance arteries

The reactivity of isolated ring segments (i.d. ca. 200 μm) of calf retinal resistance arteries to arachidonic acid derivatives were studied in vitro. Prostaglandin F 2α (PGF 2α) prostaglandin E 2 (PGE 2), and a thromboxane A 2 analogue, 9,11-dideoxy-9α,11α-epoxymethane-prostaglandin F 2α, (Tx 2α), i...

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Bibliographic Details
Published in:	Experimental eye research 1990-03, Vol.50 (3), p.305-311
Main Authors:	Nielsen, Per J., Nyborg, Niels C.Berg
Format:	Article
Language:	eng
Subjects:	Animals Arachidonic Acids - metabolism Biological and medical sciences bovine Cattle Dinoprostone - pharmacology Epoprostenol - pharmacology Eye and associated structures. Visual pathways and centers. Vision Fundamental and applied biological sciences. Psychology Isometric Contraction - drug effects Muscle Contraction - drug effects Muscle Relaxation - drug effects Muscle, Smooth, Vascular - drug effects prostaglandins Retinal Artery - drug effects Retinal Artery - physiology retinal resistance arterics Thromboxane A2 - pharmacology Vascular Resistance - drug effects Vertebrates: nervous system and sense organs
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Summary:	The reactivity of isolated ring segments (i.d. ca. 200 μm) of calf retinal resistance arteries to arachidonic acid derivatives were studied in vitro. Prostaglandin F 2α (PGF 2α) prostaglandin E 2 (PGE 2), and a thromboxane A 2 analogue, 9,11-dideoxy-9α,11α-epoxymethane-prostaglandin F 2α, (Tx 2α), induced a concentration dependent contraction with the order of potency: Tx 2α>PGE 2>PGF 2α with pD 2-values (−log[EC 50(M)]) of 6·88, 6·19 and 5·20, respectively. The maximal active tension development of the vessels induced by Tx 2α, PGE 2 and PGF 2α, were 1·57 N m −1, 1·05 N m −1 and 1·19 N m −1, corresponding to 94%, 57% and 67% of E max, respectively. The active pressure development, and estimate of the maximum pressure which the vessels may be able to contract against in vivo, was 18 kPa, 12 kPa and 14 kPa (138, 89 and 110 mmHg) for Tx 2α, PGE 2 and PGF 2α, respectively. Prostaglandin I 2 (prostacyclin, PGI 2) induced a concentration-dependent relaxation of retinal resistance arteries precontracted with 10 −5 m PGF 2α. The maximal relaxation induced by PGI 2 amounted to 65% of the control vessel response induced by PGF 2α (1·27 N m −1) with a −log[EC 50(M)] value of 6·51. The results indicate that arachidonic acid derivatives are potent and effective agents capable of regulating bovine retinal resistance artery smooth muscle tension in vitro.
ISSN:	0014-4835 1096-0007