Desmopressin-induced dog ciliary artery relaxation

Area of Science:

• Pharmacology
• Ophthalmology
• Cardiovascular Research

Background:

• The posterior ciliary arteries supply blood to the eye's ciliary body.
• Vasopressin receptors (V1 and V2) are present in vascular tissues.
• The role of desmopressin in ciliary artery function is not well understood.

Purpose of the Study:

• To investigate the effects of desmopressin on isolated dog posterior ciliary arteries.
• To elucidate the mechanisms underlying desmopressin-induced vasodilation or constriction.
• To determine the involvement of nitric oxide and vasopressin receptor subtypes.

Main Methods:

• Isolated dog posterior ciliary arteries were contracted with prostaglandin F2alpha.
• Desmopressin's effects were assessed with and without endothelium.
• Nitric oxide synthase inhibition (NG-nitro-L-arginine) and L-arginine supplementation were used.
• A selective vasopressin V1 receptor antagonist (SR49059) was employed.

Main Results:

• Desmopressin induced concentration-dependent relaxation in intact arteries, reversed to contraction upon endothelium removal.
• Relaxation was blocked by NG-nitro-L-arginine and restored by L-arginine, indicating nitric oxide mediation.
• SR49059 suppressed desmopressin-induced relaxation and inhibited contractions in endothelium-denuded arteries.
• Desmopressin was significantly less potent than arginine vasopressin.

Conclusions:

• Desmopressin relaxes dog ciliary arteries through endothelium-derived nitric oxide synthesis.
• Both vasopressin V1 and V2 receptors appear to be involved in desmopressin's vascular effects.
• These findings suggest a potential role for desmopressin in modulating ocular blood flow.