Analysis of pressurized resistance vessel diameter changes with a low cost digital image processing device

Fischer, Jörg-Gerald; Mewes, H.; Hopp, Hans-Heinrich; Schubert, Rudolf

doi:10.1016/0169-2607(96)01726-9

Cited by 19 publications

(19 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The methods used in this study will be described only briefly, because they have been presented in detail previously ( Fischer et al ., 1996 ; Schubert et al ., 1999 ).…”

Section: Methodsmentioning

confidence: 99%

Modulation of the myogenic response by neurogenic influences in rat small arteries

Anschütz

Schubert

2005

British J Pharmacology

Self Cite

View full text Add to dashboard Cite

1 The hypothesis that the amplitude of the myogenic response is modulated by factors released from nerve endings was tested in rat tail small arteries. 2 A pressure myograph in conjunction with direct stimulation of nerve endings by electrical field stimulation (EFS) was used to determine rat small artery contractile reactions. 3 Vessel pretreatment with 10 À5 M phentolamine abolished EFS-induced reactions completely indicating that they are mediated mainly by an adrenoceptor agonist, probably noradrenaline. 4 In the absence and presence of 10 À5 M phentolamine, vessel diameter changes in the pressure range from 10 to 120 mmHg were not different. 5 Vessel stimulation by (i) EFS, (ii) noradrenaline, (iii) selective stimulation of a 1 -and a 2 -receptors, (iv) serotonin, or (v) vasopressin significantly reduced the diameter change induced by stepping pressure from 10 to 40 mmHg compared to unstimulated, control vessels. 6 Vessel diameter changes induced by stepping pressure from 40 to 80 and from 80 to 120 mmHg, however, were not different in vessels stimulated with EFS and noradrenaline compared to controls. 7 In conclusion, these data show that factors released from unstimulated adrenergic nerve endings (i.e., not stimulated by EFS) are not involved in the myogenic response. In contrast, factors released upon stimulation of nerve endings can modulate the amplitude of the myogenic response, but only at low pressures. Thus, the pressure range for myogenic blood flow autoregulation is extended to lower pressures. Myogenic autoregulation of blood flow at physiological pressures is unaltered.

show abstract

“…The methods used in this study will be described only briefly, because they have been presented in detail previously ( Fischer et al ., 1996 ; Schubert et al ., 1999 ).…”

Section: Methodsmentioning

confidence: 99%

Modulation of the myogenic response by neurogenic influences in rat small arteries

Anschütz

Schubert

2005

British J Pharmacology

Self Cite

View full text Add to dashboard Cite

show abstract

“…Measurements of vessel calibre are therefore of interest both to physiologists looking to better understand the regulation of blood flow [3], [4] and to clinicians interested in the prediction, diagnosis or progression of disease [5]–[7]. Of particular importance are retinal images, as these may be used to directly visualise blood vessels non-invasively in vivo [2], [6].…”

Section: Introductionmentioning

confidence: 99%

Fast Retinal Vessel Detection and Measurement Using Wavelets and Edge Location Refinement

Bankhead¹,

Scholfield²,

McGeown³

et al. 2012

PLoS ONE

302

271

View full text Add to dashboard Cite

The relationship between changes in retinal vessel morphology and the onset and progression of diseases such as diabetes, hypertension and retinopathy of prematurity (ROP) has been the subject of several large scale clinical studies. However, the difficulty of quantifying changes in retinal vessels in a sufficiently fast, accurate and repeatable manner has restricted the application of the insights gleaned from these studies to clinical practice. This paper presents a novel algorithm for the efficient detection and measurement of retinal vessels, which is general enough that it can be applied to both low and high resolution fundus photographs and fluorescein angiograms upon the adjustment of only a few intuitive parameters. Firstly, we describe the simple vessel segmentation strategy, formulated in the language of wavelets, that is used for fast vessel detection. When validated using a publicly available database of retinal images, this segmentation achieves a true positive rate of 70.27%, false positive rate of 2.83%, and accuracy score of 0.9371. Vessel edges are then more precisely localised using image profiles computed perpendicularly across a spline fit of each detected vessel centreline, so that both local and global changes in vessel diameter can be readily quantified. Using a second image database, we show that the diameters output by our algorithm display good agreement with the manual measurements made by three independent observers. We conclude that the improved speed and generality offered by our algorithm are achieved without sacrificing accuracy. The algorithm is implemented in MATLAB along with a graphical user interface, and we have made the source code freely available.

show abstract

“…Selective alterations of pH i at constant pH o achieved with the use of NH 4 Cl are also able to induce considerable diameter changes, where removal of NH 4 Cl leads to a lowering of pH i and, in contrast to the pH o -induced pH i decrease, a vessel contraction. The methods used for the pilot studies will be described only briefly, because they have been presented in detail previously [14, 15]. …”

Section: Methodsmentioning

confidence: 99%

Protons Inhibit the BK<sub>Ca</sub> Channel of Rat Small Artery Smooth Muscle Cells

2001

Self Cite

View full text Add to dashboard Cite

The regulation of the activity of calcium-activated potassium (BK_Ca) channels by intracellular proton ions (pH_i) was investigated using the patch-clamp technique in smooth muscle cells freshly isolated from rat tail small arteries. Single-channel conductance and voltage dependence of activation were not different at pH_i 7.0, 7.4 and 7.8. However, the membrane potential at which channel open probability reached 0.5 was 74 ± 5 mV (n = 6) (mean ± SE) at pH_i 7.4 and 54 ± 2 mV (n = 4) at pH_i 7.8 under conditions of pCa 5.9, and 30 ± 5 mV (n = 5) at pH_i 7.4 and 62 ± 4 mV (n = 5) at pH_i 7.0 under conditions of pCa 5.4. Furthermore, at a membrane potential of 0 mV, the pD₂ for intracellular calcium ions was 5.19 ± 0.04 (n = 26) (mean ± SD) at pH_i 7.8, 5.02 ± 0.05 (n = 28) at pH_i 7.4, and 4.82 ± 0.05 (n = 30) at pH_i 7.0. In addition, an alteration of pH_i resulted in a profound change in the amplitude of BK_Ca currents in intact cells; it reversibly attenuated the current-voltage relationship decreasing the current by 55 ± 3% (n = 7) (p < 0.001) at 70 mV after lowering the extracellular NH₄Cl concentration to decrease the calculated pH_i from 7.2 to 6.8. Thus, alterations of pH_i in the range from 7.0 to 7.8 did not affect single-channel conductance and voltage dependence of activation but markedly altered single BK_Ca channel activity as well as intact cell BK_Ca current amplitude, where an increase of the intracellular proton concentration inhibited this channel.

show abstract

Analysis of pressurized resistance vessel diameter changes with a low cost digital image processing device

Cited by 19 publications

References 2 publications

Modulation of the myogenic response by neurogenic influences in rat small arteries

Modulation of the myogenic response by neurogenic influences in rat small arteries

Fast Retinal Vessel Detection and Measurement Using Wavelets and Edge Location Refinement

Protons Inhibit the BK<sub>Ca</sub> Channel of Rat Small Artery Smooth Muscle Cells

Contact Info

Product

Resources

About