Evidence that the contraction-induced rapid hyperemia in rabbit masseter muscle is based on a mechanosensitive mechanism, not shared by cutaneous vascular beds

2012 ◽  
Vol 113 (4) ◽  
pp. 524-531 ◽  
Author(s):  
Marco Turturici ◽  
Mazher Mohammed ◽  
Silvestro Roatta
Keyword(s):  
Masseter Muscle ◽  
Transient Flow ◽  
Artery Occlusion ◽  
Peak Amplitude ◽  
Time To Peak ◽  
Ear Artery ◽  
Vascular Beds ◽  
Spontaneous Contractions ◽  
Awake Condition ◽  
Bayliss Effect

Several mechanisms have been hypothesized to contribute to the rapid hyperemia at the onset of exercise. The aim of the present study was to investigate the role played by the mechanosensitivity of the vascular network. In 12 anesthetized rabbits blood flow was recorded from the exclusively muscular masseteric artery in response to brief spontaneous contractions (BSC) of the masseter muscle, artery occlusion (AO), muscle compression (MC), and muscle stretch (MS). Activation of masseter muscle was monitored by electromyography (EMG). Responses to AO were also recorded from the mostly cutaneous facial and the central ear arteries. Five animals were also tested in the awake condition. The hyperemic response to BSC (peak amplitude of 394 ± 82%; time to peak of 1.8 ± 0.8 s) developed with a latency of 300–400 ms from the beginning of the EMG burst and 200–300 ms from the contraction-induced transient flow reduction. This response was neither different from the response to AO (peak amplitude = 426 ± 158%), MC, and MS ( P = 0.23), nor from the BSC response in the awake condition. Compared with the masseteric artery, the response to AO was markedly smaller both in the facial (83 ± 18%,) and in the central ear artery (68 ± 20%) ( P < 0.01). In conclusion, the rapid contraction-induced hyperemia can be replicated by a variety of stimuli affecting transmural pressure in muscle blood vessels and is thus compatible with the Bayliss effect. This prominent mechanosensitivity appears to be a characteristic of muscle and not cutaneous vascular beds.

An ultrastructural analysis of the sympathetic innervation of the rabbit ear artery and middle cerebral artery and their branches

1992 ◽  
Vol 50 (1) ◽  
pp. 934-935
Author(s):  
John T. Dodge ◽  
John A. Bevan
Keyword(s):  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Sympathetic Innervation ◽  
Electrical Field Stimulation ◽  
Rabbit Ear Artery ◽  
Electrical Field ◽  
Functional Differences ◽  
Ear Artery ◽  
Rabbit Ear ◽  
Vascular Beds

Unlike many peripheral vascular beds, the sympathetic nervous system exerts little control on cerebral blood flow. The contractile response of isolated rabbit middle cerebral artery (MCA) segments to electrical field stimulation of its intramural nerves is less than in a similar-sized artery from the ear. This study was undertaken to characterize and compare the perivascular neuromuscular relationships and innervation density of similar-sized arteries varying in diameter from these two different regional arterial beds to see if there were structural correlates for these functional differences.

Abstract 4244: Longitudinal Cardiac Rotation Affects Systolic Myocardial Velocities and Velocity-Defined Measures Of Ventricular Dyssynchrony

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Zoran Popovic ◽  
Karen Phillips ◽  
Pascal Lim ◽  
John E Meulet ◽  
Conor D Barrett ◽  
...  
Keyword(s):  
Peak Systolic Velocity ◽  
Peak Amplitude ◽  
Cardiac Resynchronization ◽  
Reverse Remodeling ◽  
Lateral Velocity ◽  
Systolic Volume ◽  
Time To Peak ◽  
Chamber View ◽  
Intraventricular Dyssynchrony ◽  
End Systolic Volume

Background : Left ventricle (LV) of cardiac resynchronization therapy (CRT) candidates often displays rotational motion in the horizontal plane, a phenomenon we named longitudinal rotation (LR). We assessed if magnitude and direction of LR affects myocardial velocity-based measures of LV dyssynchrony. Methods : In 100 CRT patients (age 64±13 yrs, 76 men) LR was assessed in the apical 4-chamber view by speckle-tracking while myocardial systolic velocities of basal septum and lateral LV wall were measured from 2-dimensional color tissue Doppler data. Patients were classified into quartiles based on their LR values. Intraventricular dyssynchrony was calculated as the absolute, while septo-lateral delay was calculated as the true difference between the time to peak systolic velocity of the septum and lateral wall. Results : LR in all quartiles except Quartile 4 had a clockwise (negative) direction when viewed in apical 4-chamber view. As quartiles increased, patients were more frequently ischemic, systolic septal velocity and septo-lateral delay decreased, while intraventricular dyssynchrony showed a U shaped relationship (Table ). While difference in peak amplitude of basal septal and lateral systolic velocities and LR correlated with end-systolic volume (ESV) decrease at follow-up in non-ischemic patients (r = 0.44 and r = 0.49, p < 0.01 for both), neither intraventrivcular dyssynchrony nor septal-lateral delay correlated with ESV decrease in either etiology. Conclusions : LR affects amplitudes and timing of myocardial velocities. While difference in peak amplitude of basal septal and lateral systolic velocities and LR predict LV reverse remodeling, time-based velocity measures do not. ICM:/DCM: ischemic/dilated cardiomyopathy; T(sep/lat): time to peak (septal/lateral) systolic velocity; S(sep/lat): peak systolic (septal/lateral) velocity; S-L delay: septo-lateral delay; Dys: intraventricular dyssynchrony; ΔESV: end-systolic volume decrease

scholarly journals Imaging video plethysmography shows reduced signal amplitude in glaucoma patients in the area of the microvascular tissue of the optic nerve head

2020 ◽  
Author(s):  
Ralf-Peter Tornow ◽  
Radim Kolar ◽  
Jan Odstrcilik ◽  
Ivana Labounkova ◽  
Folkert Horn
Keyword(s):  
Optic Nerve ◽  
Ocular Hypertension ◽  
Pulse Duration ◽  
Blood Volume ◽  
Optic Nerve Head ◽  
Light Absorption ◽  
Normal Subjects ◽  
Peak Amplitude ◽  
Time To Peak ◽  
Changing Light

Abstract Purpose To measure parameters of the cardiac cycle-induced pulsatile light absorption signal (plethysmography signal) of the optic nerve head (ONH) and to compare parameters between normal subjects and patients with different stages of glaucoma. Patients and methods A recently developed video ophthalmoscope was used to acquire short video sequences (10 s) of the ONH. After image registration and trend correction, the pulsatile changing light absorption at the ONH tissue (excluding large vessels) was calculated. The changing light absorption depends on the pulsatile changing blood volume. Various parameters, including peak amplitude, steepness, time-to-peak, full width at half maximum (FWHM), and pulse duration, were calculated for averaged individual pulses (heartbeats) of the plethysmography signal. This method was applied to 19 healthy control subjects and 91 subjects with ocular hypertension, as well as different stages of primary open-angle glaucoma (17 subjects with ocular hypertension, 24 with preperimetric glaucoma, and 50 with perimetric glaucoma). Results Compared to the normal subjects, significant reductions (p < 0.001) in peak amplitude and steepness were observed in the group of perimetric glaucoma patients, but no significant difference was found for time-to-peak, FWHM, and pulse duration. Peak amplitude and steepness showed high correlations with RNFL thickness (p < 0.001). Conclusions The presented low-cost video-ophthalmoscope permits measurement of the plethysmographic signal of the ONH tissue and calculation of different blood flow-related parameters. The reduced values of the amplitude and steepness parameters in perimetric glaucoma patients suggest decreased ONH perfusion and blood volume. This outcome is in agreement with results from other studies using OCT angiography and laser speckle flowgraphy, which confirm reduced capillary density in these patients. Registration site: www.clinicaltrials.gov, Trial registration number: NCT00494923

Abstract WP65: Relationship Between Neurological Severity and CBF Grade of Mr Perfusion in Acute Stroke Patients With the Carotid Artery Occlusion

Stroke ◽  
2016 ◽  
Vol 47 (suppl_1) ◽  
Author(s):  
Yuji Takahashi ◽  
Kazuhiro Yoshioka ◽  
Shigen Kasakura ◽  
Yuhei Tanno ◽  
Tomonori Iwata ◽  
...  
Keyword(s):  
Carotid Artery ◽  
Contralateral Side ◽  
Artery Occlusion ◽  
Carotid Artery Occlusion ◽  
Mr Perfusion ◽  
Stroke Patients ◽  
Statistical Significant Difference ◽  
Time To Peak ◽  
Significant Difference ◽  
Grade Groups

Introduction: It remains unclear how strongly perfusion findings are related to neurological severity (NS) and MR-DW images (DWI). Hypothesis: CBF grade based on MR perfusion (MRp) is related to NS or DWI and can identify candidates for endovascular therapy (ET). Methods: Included in our retrospective analysis were acute ischemic stroke patients 1) who were admitted to our stroke center within 24 hours of the onset between Jan 2004 and May 2015, 2) who presented NIHSS as NS of 0 or more, 3) who underwent MRA, displaying complete occlusion of the affected carotid artery. We evaluated patients’ baseline features, NIHSS, DWI-ASPECTS (ACT) at arrival and CBF grade, which was calculated by using bilateral time-intensity curves (TICs) of MR perfusion. According to the time to peak (TP) and the peak signal (PS) comparing the affected side (a) with the contralateral side (c), we regarded the affected-sided PSa divided by TPa as possible CBFa and the contralateral-sided PSc divided by TPc as possible CBFc. CBF grade 1 was defined as CBFa divided by CBFc (CBF%) less than 0.2, grade 2 as CBF% of 0.2 or more and CBF% less than 0.7 and grade 3 as CBF% of 0.7 or more. Results: During the study period, 176 patients matched our criteria for analysis. Median NIHSS was 18, and median ACT was 6. There were 30 patients with CBF grade1, 81 with grade2 and 65 with grade3. Median NIHSS in grade1, 2, and 3 patients was 23, 19, and 7 (p<0.0001), respectively, and there was a statistical significant difference between any grade groups (p<0.016). Median ACT in grade1, 2, and 3 was 1, 5, and 8 (p<0.0001), respectively, and there was a statistical significant difference between any grade groups (p<0.016). Among 32 patients with NIHSS of 7 or less and ACT of 8 or more, there were 28 (87.5%) in grade3. Among 10 patients with NIHSS of 23 or more and ACT of 1 or less, there were 9 (90%) in grade1. Among 40 patients with NIHSS of 8 or more and ACT of 8 or more, there was 22 (55%) in grade2 and 18 (45%) in grade3. Conclusion: CBF grade defined by MRp had strong relation to NIHSS and ACT. Patients with lower NIHSS score but higher ACT score were probable candidates for ET and many among them belonged to CBF grade2.

Perfused microvascular morphometry during middle cerebral artery occlusion

1988 ◽  
Vol 255 (3) ◽  
pp. H623-H628 ◽  
Author(s):  
E. Buchweitz-Milton ◽  
H. R. Weiss
Keyword(s):  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Regional Differences ◽  
Fluorescein Isothiocyanate ◽  
Artery Occlusion ◽  
Capillary Bed ◽  
Morphometric Index ◽  
Contralateral Cortex ◽  
Vascular Beds ◽  
Cerebral Artery Occlusion

This study compared the arteriolar and capillary bed perfusion in the ischemic vs. contralateral cortex 1 h after middle cerebral artery (MCA) ligation in anesthetized rat. Fluorescein isothiocyanate (FITC)-dextran identified the perfused vascular beds. Regional cerebral blood flow (CBF) was monitored with [14C]iodoantipyrine. Morphometric parameters were determined through comparisons of the perfused FITC-labeled vessels with alkaline phosphatase-stained preparations of the total microvascular network. Regional CBF was significantly different when the contralateral cortex (54 +/- 7 ml.min-1.100 g-1) (means +/- SE) and the MCA-occluded cortex (31 +/- 8 ml.min-1.100 g-1) were compared. There were no significant regional differences in any morphometric index of structure in the total microvascular bed. The percentage of the total capillary and arteriolar volume that was perfused in the MCA-ligated cortex was significantly lower than the value obtained from the contralateral cortex. The change in the perfusion pattern of the cerebral microvasculature in the ischemic cortex was not due to vessel blockade. The altered temporal perfusion pattern of capillary and arteriolar vessels in the occluded cortex may be due to an altered microvascular perfusion cycle, longer perfusion pathways, vasoconstriction, or partial vessel obstruction.

α-Toxin perfusion: a new method for selective impairment of endothelial function in isolated vessels or intact vascular beds

1995 ◽  
Vol 73 (11) ◽  
pp. 1669-1673 ◽  
Author(s):  
I. Laher ◽  
N. Thorin-Trescases ◽  
A. Ding ◽  
R. Laporte ◽  
G. Osol
Keyword(s):  
Smooth Muscle ◽  
Endothelial Function ◽  
Side Branch ◽  
Vascular Endothelial ◽  
Vascular Endothelial Function ◽  
Membrane Pore ◽  
Small Arteries ◽  
Ear Artery ◽  
Vascular Beds ◽  
Selective Impairment

We describe a method for selectively permeabilizing endothelial ceils, using the membrane pore forming exoprotein Staphylococcus aureus α-toxin. Experiments were performed in rabbit central ear artery or its main side branch under isometric conditions, on the isolated perfused kidney, or in cannulated pressurized renal arteries. In presence of α-toxin, endothelial-dependent vasodilator responses elicited by acetylcholine or A23187 were abolished, whereas the sensitivity of smooth muscle cells to constrictors (norepinephrine, phenylephrine, or KCl) or dilators (sodium nitroprusside) was not affected. The results indicate that restricting the α-toxin to the luminal surface induces selective impairment of vascular endothelial function. This method of eliminating endothelium-dependent vasodilator responses may prove to be useful in the study of endothelial – smooth muscle interactions of isolated small arteries and intact vascular beds.Key words: α-toxin, endothelium, vasodilation, vascular smooth muscle.

Effect of temperature on spike-triggered average torque and electrophysiological properties of low-threshold motor units

2005 ◽  
Vol 99 (1) ◽  
pp. 197-203 ◽  
Author(s):  
Dario Farina ◽  
Lars Arendt-Nielsen ◽  
Thomas Graven-Nielsen
Keyword(s):  
Action Potential ◽  
Skin Temperature ◽  
Motor Unit ◽  
Conduction Velocity ◽  
Discharge Rate ◽  
Peak Amplitude ◽  
Single Motor Unit ◽  
Time To Peak ◽  
Low Threshold ◽  
Electromyographic Signals

The aim of the study was to jointly analyze temperature-induced changes in low-threshold single motor unit twitch torque and action potential properties. Joint torque, multichannel surface, and intramuscular electromyographic signals were recorded from the tibialis anterior muscle of 12 subjects who were instructed to identify the activity of a target motor unit using intramuscular electromyographic signals as feedback. The target motor unit was activated at the minimum stable discharge rate in seven 3-min-long contractions. The first three contractions (C1–C3) were performed at 33°C skin temperature. After 5 min, the subject performed three contractions at 33°C (T1), 39°C (T2), and 45°C (T3), followed by a contraction at 33°C (C4) skin temperature. Twitch torque and multichannel surface action potential of the target motor unit were obtained by spike-triggered averaging. Discharge rate (mean ± SE, 7.1 ± 0.5 pulses/s), interpulse interval variability (35.8 ± 9.2%), and recruitment threshold (4.5 ± 0.4% of the maximal voluntary torque) were not different among the seven contractions. None of the investigated variables were different among C1–C3, T1, and C4. Conduction velocity and peak twitch torque increased with temperature ( P < 0.05; T1: 3.53 ± 0.21 m/s and 0.82 ± 0.23 mN·m, T2: 3.93 ± 0.24 m/s and 1.17 ± 0.36 mN·m, T3: 4.35 ± 0.25 m/s and 1.46 ± 0.40 mN·m, respectively). Twitch time to peak and surface action potential peak-to-peak amplitude were smaller in T3 (61.8 ± 2.0 ms and 27.4 ± 5.1 μV, respectively) than in T1 (71.9 ± 4.1 ms and 35.0 ± 6.5 μV, respectively) ( P < 0.05). The relative increase in conduction velocity between T1 and T3 was positively correlated ( P < 0.05) with the increase in twitch peak amplitude ( r2 = 0.48), with the decrease in twitch time to peak ( r2 = 0.43), and with the decrease in action potential amplitude ( r2 = 0.50). In conclusion, temperature-induced modifications in fiber membrane conduction properties may have a direct effect on contractile motor unit properties.

scholarly journals Botulinum Toxin Therapy for Managing Sleep Bruxism: A Randomized and Placebo—Controlled Trial

Toxins ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 168
Author(s):  
Young Joo Shim ◽  
Hee Jin Lee ◽  
Keun Jeong Park ◽  
Hyung Tack Kim ◽  
Il Hee Hong ◽  
...  
Keyword(s):  
Placebo Group ◽  
Botulinum Toxin ◽  
Treatment Group ◽  
Masseter Muscle ◽  
Controlled Trial ◽  
Group Interaction ◽  
Sleep Bruxism ◽  
Peak Amplitude ◽  
Significant Time ◽  
Botulinum Toxin Therapy

The purpose of this study is to evaluate the effects of botulinum toxin type A (BoNT-A) for managing sleep bruxism (SB) in a randomized, placebo-controlled trial. Thirty SB subjects were randomly assigned into two groups evenly. The placebo group received saline injections into each masseter muscle, and the treatment group received BoNT-A injections into each masseter muscle. Audio–video–polysomnographic recordings in the sleep laboratory were made before, at four weeks after, and at 12 weeks after injection. Sleep and SB parameters were scored according to the diagnostic and coding manual of American Academy of Sleep Medicine. The change of sleep and SB parameters were investigated using repeated measures analysis of variance (RM-ANOVA). Twenty-three subjects completed the study (placebo group 10, treatment group 13). None of the SB episode variables showed a significant time and group interaction (p > 0.05) except for electromyography (EMG) variables. The peak amplitude of EMG bursts during SB showed a significant time and group interaction (p = 0.001). The injection decreased the peak amplitude of EMG bursts during SB only in the treatment group for 12 weeks (p < 0.0001). A single BoNT-A injection cannot reduce the genesis of SB. However, it can be an effective management option for SB by reducing the intensity of the masseter muscle.

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