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S Cringle

Publications and source records attributed to S Cringle.

7 recordsLinked to original sources
PubMed1998

Preservation of vasoactive properties of human retinal arteries after cryopreservation.

PURPOSE: Although we have several established in vitro systems for studying the vasoactive properties of the ocular vasculature, the restricted availability of human donor tissue has forced us to rely predominantly on animal studies. METHODS: The present paper describes, for the first time, a controlled-rate cryopreservation technique capable of maintaining vasoactive function in human retinal arteries after extended storage. RESULTS/CONCLUSION: The response to constrictive (endothelin-I) and vasodilatory agents (nimodipine and betaxolol) was comparable with that in fresh pig vessels. It is now possible to obtain multiple segments of retinal artery from a single donor eye and to preserve them for detailed pharmacological assessment.

Aged↗
PubMed1998

Overview of studies on metabolic and vascular regulatory changes in early diabetic retinopathy.

The present review provides an overview of recent research describing functional changes to the retinal vasculature in very early diabetes. The research focuses on the streptozotocin rat model after 4-6 weeks of induced diabetes and describes functional changes to retinal blood flow, vascular control and retinal oxygenation, as well as a strong vasodilatory response to insulin in the retinal vasculature. The review raises the question of whether choroid dysfunction is also a feature of diabetic retinopathy.

Animals↗
PubMed1996

Oxygen consumption in the avascular guinea pig retina.

Oxygen consumption across the retina of a mammal with a naturally avascular retina has not previously been investigated. The oxygen consumption across the avascular retina of the guinea pig was measured in vivo by spatial analysis of the intraretinal oxygen profile. The avascular nature of the guinea pig retina allows the inner retina to be included in the analysis without disrupting the normal physiological state of the retina. Oxygen-sensitive microelectrodes (1-micron tip) were used to make high-resolution measurements of oxygen tension through the retina of anesthetized, mechanically ventilated guinea pigs (n = 10). Oxygen profiles were then analyzed in terms of oxygen tension as a function of distance from the choriocapillaris/Bruch's membrane, and the data were fitted to an established mathematical model of retinal oxygen consumption. The average oxygen consumption of the full thickness of the guinea pig retina was 1.1 +/- 0.09 ml O2.min-1 x 100 g-1 (n = 10). The average oxygen consumption of the outer half of the retina was 2.07 +/- 0.17 ml O2.min-1 x 100 g-1, while that of the inner half was only 0.12 +/- 0.04 ml O2.min-1 x 100 g-1. A localized region of high oxygen consumption was identified in the outer retina in every case, and this region accounted for an average of 93.9 +/- 2.0% of the total retinal oxygen consumption. Only 5.2 +/- 1.4% of the total oxygen consumption was attributable to the inner half of the retina. When choroidal oxygen tension was increased via a combination of systemic hyperoxia and hypercapnia, high oxygen levels could be sustained in all retinal layers. Under these conditions of an excess oxygen supply, the inner retina still consumed only 0.45 +/- 0.11 ml O2.min-1 x 100 g-1, which was 13.8 +/- 2.5% of the total retinal oxygen consumed. The relatively low oxygen consumption in the inner retina of the guinea pig may reflect an interesting adaptation to the constraints imposed by the absence of a retinal circulation in this species.

Animals↗
PubMed1992

Oxygen tension and blood flow in the retina of normal and diabetic rats.

The use of microelectrode techniques for studying oxygen distribution and blood flow in the eye of a physiologically well maintained rat provides a very convenient model in which to study oxygen supply to the retina. The availability of rat models of vascular disease such as diabetes and hypertension, and the existence of several models of retinal degeneration, make studies of oxygen supply in the rat eye of particular relevance. The experiments reported in this paper demonstrate changes in oxygen distribution and blood flow very early in STZ induced diabetes. Thus, we have established a preparation in which the role of changes in oxygen supply can be correlated with the pathological events that are apparent later in the disease.

Animals↗