Electrical analog model of arterial compliance during reactive hyperemia

2011 ◽  
Author(s):  
Layli S. Goldoozian ◽  
Edmond Zahedi
Keyword(s):  
Arterial Compliance ◽  
Reactive Hyperemia ◽  
Analog Model ◽  
Electrical Analog

scholarly journals Time course of forearm arterial compliance changes during reactive hyperemia

2001 ◽  
Vol 281 (3) ◽  
pp. H1093-H1103 ◽  
Author(s):  
Damiano Baldassarre ◽  
Mauro Amato ◽  
Carlo Palombo ◽  
Carmela Morizzo ◽  
Linda Pustina ◽  
...  
Keyword(s):  
Time Course ◽  
Arterial Compliance ◽  
Reactive Hyperemia ◽  
Low Density Lipoprotein ◽  
Arterial Occlusion ◽  
Density Lipoprotein ◽  
Peak Time ◽  
Continuous Measurements ◽  
Measurement Protocol ◽  
Plasma High Density

Ultrasonic studies have shown that arterial compliance increases after prolonged ischemia. The objective of the present study was to develop an alternative plethysmographic method to investigate compliance, exploring validity and clinical applicability. Forearm pulse volume (FPV) and blood pressure (BP) were used to establish the FPV-BP relationship. Forearm arterial compliance (FAC) was measured, and the area under the FAC-BP curve (FACAUC) was determined. The time course curve of compliance changes during reactive hyperemia was obtained by continuous measurements of FACAUCfor 20 s before and for 300 s after arterial occlusion. This technique allows us to effectively assess compliance changes during reactive hyperemia. Furthermore, the selected measurement protocol indicated the necessity for continuous measurements to detect “true” maximal FACAUCchanges. On multivariate analysis, preischemic FACAUCwas mainly affected by sex, peak FACAUCwas affected by sex and systolic BP, percent changes were affected by plasma high-density and low-density lipoprotein cholesterol, peak time was affected by age and body mass index, and descent time was affected by plasma triglyceride levels. The proposed technique is highly sensitive and well comparable with the generally accepted echotracking system. It may thus be considered as an alternative tool to detect and monitor compliance changes induced by arterial occlusion.

Linear relation between time constant of oxygen uptake kinetics, total creatine, and mitochondrial content in vitro

2008 ◽  
Vol 294 (1) ◽  
pp. C79-C87 ◽  
Author(s):  
Brian Glancy ◽  
Thomas Barstow ◽  
Wayne T. Willis
Keyword(s):  
Time Constant ◽  
Mitochondrial Protein ◽  
Oxygen Uptake Kinetics ◽  
Analog Model ◽  
Electrical Analog ◽  
Skeletal Muscle Mitochondria ◽  
Rate Of Oxygen Consumption ◽  
Total Creatine ◽  
Kinetics Of

Following the onset of moderate aerobic exercise, the rate of oxygen consumption (Jo) rises monoexponentially toward the new steady state with a time constant (τ) in the vicinity of 30 s. The mechanisms underlying this delay have been studied over several decades. Meyer's electrical analog model proposed the concept that the τ is given by τ = Rm· C, where Rm is mitochondrial resistance to energy transfer, and C is metabolic capacitance, determined primarily by the cellular total creatine pool (TCr = phosphocreatine + creatine). The purpose of this study was to evaluate in vitro the Jo kinetics of isolated rat skeletal muscle mitochondria at various levels of TCr and mitochondrial protein. Mitochondria were incubated in a medium containing 5.0 mM ATP, TCr pools of 0–1.5 mM, excess creatine kinase, and an ATP-splitting system of glucose + hexokinase (HK). Pyruvate and malate (1 mM each) were present as oxidative substrates. Jo was measured across time after HK was added to elicit one of two levels of Jo (40 and 60% of state 3). At TCr levels (in mM) of 0.1, 0.2, 0.3, 0.75, and 1.5, the corresponding τ values (s, means ± SE) were 22.2 ± 3.0, 36.3 ± 2.2, 65.7 ± 4.3, 168.1 ± 22.2, and 287.3 ± 25.9. Thus τ increased linearly with TCr ( R2 = 0.916). Furthermore, the experimentally observed τ varied linearly and inversely with the mitochondrial protein added. These in vitro results consistently conform to the predictions of Meyer's electrical analog model.

A Simple Two-Dimensional Electrical Analog Model for Wind-Driven Circulation in the Gulf of St. Lawrence

1966 ◽  
Vol 23 (9) ◽  
pp. 1411-1438 ◽  
Author(s):  
B. L. Blackford
Keyword(s):  
Mathematical Model ◽  
Pressure Gradients ◽  
Two Dimensional ◽  
Analog Model ◽  
Analog Simulation ◽  
Electrical Analog ◽  
Horizontal Pressure ◽  
Excitation Force ◽  
Comparison Of The Results

A mathematical model of water circulation in an enclosed basin was examined, taking into account the effects of vertical friction, Coriolis force, and horizontal pressure gradients. Wind stress at the free surface was the only excitation force taken into account. The resulting vorticity equation was applied to the Gulf of St. Lawrence by using an electrical analog simulation technique. Solutions were obtained for two situations: one in which the circulation was vertically averaged and another which showed the circulation at several depths. Comparison of the results with broad features of the Gulf circulation derived from synoptic surveys suggested that the wind plays an important role in producing the long-term circulation. The model did not duplicate all of the features of the long-term circulation, but suggested several phenomena for further direct study.

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