L-NAME- and U 46619-induced contractions in isolated porcine ciliary arteries versus vortex veins

Pellanda, Niccolò; Haefliger, Ivan O.

doi:10.1055/s-2001-15902

Cited by 10 publications

(6 citation statements)

References 10 publications

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“…153 The role of blood pressure in glaucoma He, Vingrys, Armitage and Bui at the ONH has been implicated in the pathogenesis of glaucoma. 153 Studies in both ocular 154 and cerebral tissues 155 demonstrate the existence of a basal release of nitric oxide, which means that there is active vasodilation under physiological conditions. This basal level of vasodilation allows the vascular tone to be either increased (constricted) or decreased quickly during changes in the perfusion pressure.…”

Section: Mechanisms Of Autoregulationmentioning

confidence: 99%

The role of blood pressure in glaucoma

Vingrys

Armitage

2011

Clinical and Experimental Optometry

119

106

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Although intraocular pressure (IOP) remains an important risk factor for glaucoma, it is clear that other factors can also influence disease development and progression. More recently, the role that blood pressure (BP) has in the genesis of glaucoma has attracted attention, as it represents a clinically modifiable risk factor and thus provides the potential for new treatment strategies beyond IOP reduction. The interplay between blood pressure and IOP determines the ocular perfusion pressure (OPP), which regulates blood flow to the optic nerve. If OPP is a more important determinant of ganglion cell injury than IOP, then hypotension should exacerbate the detrimental effects of IOP elevation, whereas hypertension should provide protection against IOP elevation. Epidemiological evidence provides some conflicting outcomes of the role of systemic hypertension in the development and progression of glaucoma. The most recent study showed that patients at both extremes of the blood pressure spectrum show an increased prevalence of glaucoma. Those with low blood pressure would have low OPP and thus reduced blood flow; however, that people with hypertension also show increased risk is more difficult to reconcile. This finding may reflect an inherent blood flow dysregulation secondary to chronic hypertension that would render retinal blood flow less able to resist changes in ocular perfusion pressure. Here we review both clinical and experimental studies that have attempted to clarify the relationships among blood pressure, OPP and blood flow autoregulation in the pathogenesis of glaucoma.

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Section: Mechanisms Of Autoregulationmentioning

confidence: 99%

The role of blood pressure in glaucoma

Vingrys

Armitage

2011

Clinical and Experimental Optometry

119

106

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“…In general the regulation of arteries has attracted more attention [39, 40], although veins are also highly regulated [41]. Among many factors involved, two factors are of special interest in this context: Endothelin-1 (ET-1) for vasoconstriction [42] and the vascular endothelial growth factor (VEGF) for vessel permeability [43].…”

Section: The Concept Of Functional Dysregulation Of the Veinmentioning

confidence: 99%

“…This may lead to some constriction of the arteries but even more of the adjacent veins. Veins respond at lower concentrations to vasoconstrictive molecules than arteries [41]. And in addition ET-1 stimulates arterial wall fibrosis further contributing to a narrowing of the vein.…”

Section: The Concept Of Functional Dysregulation Of the Veinmentioning

confidence: 99%

Retinal vein occlusions: The potential impact of a dysregulation of the retinal veins

2010

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A retinal vein occlusion (RVO) is a sight threatening disease. It can be divided into central vein occlusion and branch retinal vein occlusion. The pathogenesis of the condition remains to be solved. Mechanical compression of the vessel wall or thrombotic occlusion of the vessel lumen, sometimes combined with rheological disorders, are often assumed pathomechanisms. Accordingly, the therapy relies either on mechanical decompression, lyses of thrombi or improvement of rheology. A number of observations however, such as the relationship of RVO to atherosclerotic risk factors, spontaneous reversibility particularly in young patients, rest flow observed in angiography, occlusion despite anticoagulation or thrombocytopenia and finally the positive effect of anti-VEGF therapy are not explained by the present pathogenetic concept. As a new concept we propose a local venous constriction induced by vasoconstrictive molecules diffusing from neighbouring diseased arteries and/or from other neighbouring (hypoxic) tissues. Recognizing these postulated conditions might lead to an earlier identification of impending vein occlusions as well as to a treatment more tailored to the risk factor constellation of the particular patient.

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“…Further studies explored the effect of ACE inhibitors and angiotensin receptor antagonists [123], of CCBs [124] at high and low doses [125], dipyridamole [126], potassium-channel blockers [127] and openers [128], magnesium [129], ox-LDL and the ET antagonists BQ 123 [130] and avosentan [131], bimatoprost [132], carteolol [133, 134], PGF2alpha [135] travoprost [136], latanoprost [137, 138], melatonin [139] and adrenomedullin [140]. We also studied the regulation of the vortex vein [101]. Findings with isolated vessels were then also confirmed in a perfused eye model [141] (Fig.…”

Section: Regulation Of Ocular Vessels In Ex Vivo Studiesmentioning

confidence: 99%

The discovery of the Flammer syndrome: a historical and personal perspective

Flammer

Konieczka

2017

EPMA Journal

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This review describes the clinical and basic research that led to the description of Flammer syndrome. It is narrated from a personal perspective. This research was initiated by the observation of an increased long-term fluctuation of visual fields in a subgroup of glaucoma patients. As these patients had strikingly cold hands, peripheral blood flow was tested with a capillary microscopy, and vasospastic syndrome (VS) was diagnosed. Further studies on these patients revealed frequently weakened autoregulation of ocular blood flow and increased flow resistivity in retroocular vessels. Their retinal vessels were more rigid and irregular and responded less to flickering light. Holistic investigation demonstrated low blood pressure, silent myocardial ischaemia, altered beat-to-beat variation, altered gene expression in the lymphocytes, slightly increased plasma endothelin level and increased systemic oxidative stress. This combination of signs and symptoms was better described by the term primary vascular dysregulation (PVD) than by VS. Subsequent studies showed additional symptoms frequently related to PVD, such as low body mass index, cold extremities combined with slightly increased core temperature, prolonged sleep onset time, reduced feelings of thirst, increased sensitivity to smell and also for certain drugs and increased retinal venous pressure. To better characterise this entire syndrome, the term Flammer syndrome (FS) was introduced. Most subjects with FS were healthy. Nevertheless, FS seemed to increase the risk for certain eye diseases, particularly in younger patients. This included normal-tension glaucoma, anterior ischaemic optic neuropathy, retinal vein occlusions, Susac syndrome and central serous chorioretinopathy. Hereditary diseases, such as Leber’s optic neuropathy or retinitis pigmentosa, were also associated with FS, and FS symptoms and sings occurred more frequent in patients with multiple sclerosis or with acute hearing loss. Further research should lead to a more concise definition of FS, a precise diagnosis and tools for recognizing people at risk for associated diseases. This may ultimately lead to more efficient and more personalised treatment.

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L-NAME- and U 46619-induced contractions in isolated porcine ciliary arteries versus vortex veins

Abstract: When compared with KCl-induced contractions, contractions evoked by U 46619 or L-NAME are proportionally higher in porcine vortex veins than in ciliary arteries.

Cited by 10 publications

References 10 publications

The role of blood pressure in glaucoma

The role of blood pressure in glaucoma

Retinal vein occlusions: The potential impact of a dysregulation of the retinal veins

The discovery of the Flammer syndrome: a historical and personal perspective

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