A simple method for volumetric measurements in isolated cardiac muscle

1979 ◽  
Vol 236 (3) ◽  
pp. H519-H524
Author(s):  
S. R. Houser ◽  
A. R. Freeman
Keyword(s):  
Cardiac Muscle ◽  
Cell Volume ◽  
Extracellular Space ◽  
Voltage Drop ◽  
Electrical Current ◽  
Experimental Chamber ◽  
Papillary Muscles ◽  
Simple Method ◽  
Disease States ◽  
Direct Electrical Current

A new method for the study of extracellular space and cell volume of cardiac muscle is described. Canine cardiac Purkinje strands and cat papillary muscles were placed within a fluid-filled aperture connecting two sides of an experimental chamber. Direct electrical current was passed through the hole, and changes in the voltage drop across it were correlated with Purkinje strand extracellular space and cell volume. The results of experiments on 21 Purkinje strands and 4 papillary muscles yielded an extracellular space of 51 +/- 2.1% (SEM) and 23.3 +/- 2.1%, respectively. When strands were superfused with hyper- (600 mosM) and hyposmotic (150 mosM) solutions, the preparations were found to attain new steady-state volumes that were 75 +/- 3.1% and 121 +/- 9% of control, respectively. This method can be used for volumetric studies in numerous cardiac muscle preparations and should be applicable to the study of volume abnormalities associated with certain disease states.

Early transient depletion of extracellular Ca during individual cardiac muscle contractions

1983 ◽  
Vol 244 (3) ◽  
pp. H462-H468 ◽  
Author(s):  
D. M. Bers
Keyword(s):  
Action Potential ◽  
Cardiac Muscle ◽  
Extracellular Space ◽  
Muscle Contractions ◽  
Cardiac Cells ◽  
Papillary Muscles ◽  
Tension Development ◽  
Time Constants ◽  
Recorded Signal ◽  
Direct Activation

Extracellular free [Ca] in rabbit papillary muscles was monitored using double-barreled Ca microelectrodes. These electrodes had tip diameters of 4-12 microns, electrical time constants of 2-5 ms, and electrochemical time constants of less than 30 ms. During individual beats a transient depletion of extracellular Ca (CaO) was recorded. This decrease of [Ca]O begins very early during the action potential, before significant tension development, and reaches a maximum much before the peak of developed tension (T). The depletion of CaO is blocked by CoCl2 or verapamil and enhanced by 10(-8) M isoproterenol or reduction of extracellular Na concentration to 35 mM. The magnitude of this early depletion of CaO increases in parallel with tension as a function of [Ca]O (8.46 +/- 0.98 microM at 0.2 mM CaO, 16.9 +/- 1.6 microM at 0.5 mM CaO, and 44.7 +/- 3.7 microM at 2.0 mM CaO). However the magnitude (in mV) of the recorded signal decreases with increasing [Ca]O and T, suggestive of saturation. The magnitude of this early transient CaO depletion also increases in parallel with the increase of T produced by initiating stimulation from rest (except for the first beat, which may be more dependent on stored Ca). It is probable that the depletions recorded represent Ca influx into cardiac cells from the extracellular space. The magnitude of Ca influx represented by the CaO depletions is difficult to quantitate but may be roughly in the range of Ca entry that would be required for direct activation of the myofilaments.

Safe control of palmoplantar hyperhidrosis with direct electrical current

2002 ◽  
Vol 41 (9) ◽  
pp. 602-605 ◽  
Author(s):  
Yunus Karakoç ◽  
Ertuğrul H. Aydemir ◽  
M. Tunaya Kalkan ◽  
Gaye Ünal
Keyword(s):  
Electrical Current ◽  
Direct Electrical Current ◽  
Safe Control

Calcium is released from the junctional sarcoplasmic reticulum during cardiac muscle contraction

1991 ◽  
Vol 260 (3) ◽  
pp. H989-H997 ◽  
Author(s):  
C. S. Moravec ◽  
M. Bond
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Muscle Contraction ◽  
Cardiac Muscle ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Storage Site ◽  
Papillary Muscles ◽  
Cardiac Muscle Contraction ◽  
Intracellular Storage ◽  
Junctional Sarcoplasmic Reticulum

We have used electron-probe microanalysis (EPMA) to address the question of Ca2+ release by junctional sarcoplasmic reticulum (JSR) as well as Ca2+ regulation by mitochondria (MT) during cardiac muscle contraction. Hamster papillary muscles were rapidly frozen during relaxation or at the peak rate of tension rise (+dT/dt). Total Ca2+ content was measured by EPMA in the JSR, within a MT, over the A band, and in the whole cell, in nine cells per animal (five animals per group). JSR Ca2+ content was found to be significantly lower in muscles frozen at the peak of contraction [7.3 +/- 1.3 (mean +/- SE) mmol Ca2+/kg dry wt] than in those frozen during relaxation (12.5 +/- 1.9 mmol Ca2+/kg dry wt; P less than 0.01), suggesting that Ca2+ is released from this storage site during cardiac muscle contraction. In contrast, MT Ca2+ content did not change significantly during contraction (0.4 +/- 0.1 mmol/kg dry wt) compared with relaxation (0.1 +/- 0.2 mmol/kg dry wt). A third group of muscles was frozen during relaxation after pretreatment with 10(-7) M ryanodine. Ca2+ content of the JSR was significantly decreased (P less than 0.01) in this group of muscles, (6.4 +/- 1.8 mmol/kg dry wt) compared with those frozen during relaxation in the absence of the drug. This suggests that the intracellular storage site with a decreased Ca2+ content in muscles frozen at the peak of contraction is the ryanodine-releasable store. These results provide the first direct measurement of the Ca2+ content of both JSR and MT during a normal cardiac muscle contraction and demonstrate that Ca2+ is released from the JSR during muscle contraction.

Stimulation of bone formation by direct electrical current in an orthopedically expanded suture in the rat

2010 ◽  
Vol 40 (2) ◽  
pp. 106 ◽  
Author(s):  
Tancan Uysal ◽  
Mihri Amasyali ◽  
Huseyin Olmez ◽  
Yildirim Karslioglu ◽  
Omer Gunhan
Keyword(s):  
Bone Formation ◽  
Electrical Current ◽  
Direct Electrical Current ◽  
Stimulation Of

Isotonic relaxation in cardiac muscle

1975 ◽  
Vol 229 (3) ◽  
pp. 646-651 ◽  
Author(s):  
JE Strobeck ◽  
AS Bahler ◽  
EH Sonnenblick
Keyword(s):  
Cardiac Muscle ◽  
Isometric Force ◽  
Muscle Length ◽  
Constant Load ◽  
Papillary Muscles ◽  
Initial Length ◽  
Total Load ◽  
Relaxation Velocity ◽  
Force Velocity ◽  
Maximum Isometric Force

The force-velocity-length determinants of isotonic relaxation were studied in 12 cat papillary muscles. Isotonic relaxation velocity (VL) was found to be a function of total load (preload + afterload), with peak VL increasing to a maximum at loads approximately .3 to .4 Po(L') (Po(L') defined as maximum isometric force developed during a twitch at the experimental length) and falling with increasing loads. Initial muscle length (ML) had no effect on the peak VL with constant load. Increasing the initial length at which isotonic relaxation occurred (LL) decreased peak VL but did not alter the unique length-velocity trajectory at constant load. This unique length-velocity trajectory occurred, despite a wide variation in time during the contraction when peak VL was measured. Increasing Ca++ from 2.5 to 7.5 mM increased peak VL (1.73 +/- .16 to 2.32 +/- .20 ML/s) and shifted the entire length-velocity trajectory toward higher velocities of lengthening. The addition of 10 mM caffeine increased peak VL also (1.67 +/- .18 to 2.54 +/- .20 ML/s) and had a similar effect on the length-velocity trajectory during lengthening as Ca++. Both increased Ca++ and caffeine (10 mM) augmented the maximum VL measured on addition of load.

scholarly journals Fast and Sensitive Detection of Bacillus anthracis Spores by Immunoassay

2012 ◽  
Vol 78 (18) ◽  
pp. 6491-6498 ◽  
Author(s):  
Nathalie Morel ◽  
Hervé Volland ◽  
Julie Dano ◽  
Patricia Lamourette ◽  
Patricia Sylvestre ◽  
...  
Keyword(s):  
Bacillus Anthracis ◽  
Electrical Current ◽  
Biological Weapons ◽  
Meso Scale Discovery ◽  
Simple Method ◽  
Content Type ◽  
Bacillus Anthracis Spores ◽  
Luminescent Signal ◽  
Sample Purification ◽  
Phosphate Buffered Saline

ABSTRACTBacillus anthracisis one of the most dangerous potential biological weapons, and it is essential to develop a rapid and simple method to detectB. anthracisspores in environmental samples. The immunoassay is a rapid and easy-to-use method for the detection ofB. anthracisby means of antibodies directed against surface spore antigens. With this objective in view, we have produced a panel of monoclonal antibodies againstB. anthracisand developed colorimetric and electrochemiluminescence (ECL) immunoassays. Using Meso Scale Discovery ECL technology, which is based on electrochemiluminescence (ECL) detection utilizing a sulfo-Tag label that emits light upon electrochemical stimulation (using a dedicated ECL plate reader, an electrical current is placed across the microplate with electrodes integrated into the bottom of the plate, resulting in a series of electrically induced reactions leading to a luminescent signal), a detection limit ranging between 0.3 × 103and 103CFU/ml (i.e., 30 to 100 spores per test), depending on theB. anthracisstrain assayed, was achieved. In complex matrices (5 mg/ml of soil or simulated powder), the detection level (without any sample purification or concentration) was never altered more than 3-fold compared with the results obtained in phosphate-buffered saline.

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