The Role of Nitric Oxide in Modulating Retinal, Choroidal, and Anterior Uveal Blood Flows in the Domestic Piglet
Abstract
The role of nitric oxide In modulating the autoregulatory capacity of the retinal circulation and In maintaining the basal vascular tone of the weal circulation was investigated. Volumetric blood flow(ml/min/100 gm dry weight) to ocular tissues was determined in 23 anesthetized piglets (3-4 kg)using slx radiolabelled microspheres. Temporal control studies (n=6) were performed to determine optimal post-surgical time for subsequent blood flow measurements. Additional experiments were conducted utilizing the Inactive enantiomer D-NAME as vehicle control (n=6) and L-NAME as an inhibitor of nitric oxide synthase (n=6). Ocular perfusion pressure was defined as mean arterial pressure minus Intraocular pressure. Intraocular pressure was manipulated hydrostatically by needle cannulation of the anterior chamber of the eye. Ocular perfusion pressure was decreased during intravenous Infusion (30mg/kg/hr) of either D-NAME or L-NAME. Blood flows were determined at baseline and ocular perfusion pressures of: 50, SO, 40, 30, and 20 mmHg. Compared to D-NAME treated animals mean baseline choroidal and anterior weal blood flows with L-NAME showed a 47%and 43% reduction (p<.001) respectively, while mean baseline retinal blood flow did not differ. Retinal blood flow with L-NAME was reduced at all other ocular perfusion pressures when compared to DNAME (repeated measures ANOVA:protected T-tests p<.05). Both groups revealed partial retinal blood flow autoregulation as determined by dosed loop gain formula. Retinal autoregulation was significantly compromised with L-NAME.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 17, 1993
- Accession Number
- AD1011280
Entities
People
- Jorge L. Jacot
Organizations
- Uniformed Services University of the Health Sciences