Mechanostimulation, electrostimulation and force measurement in an in vitro model of the isolated rat diaphragm.
In an in vitro model of the entire rat diaphragm, diaphragmatic contraction forces at defined preload levels were investigated. A total of 24 excised rat diaphragms were electrically stimulated inside a two-chamber strain-applicator. The resulting contraction forces were determined on eight adjusted preload levels via measuring the elicited pressure in the chamber below the diaphragm. Subsequently, diaphragms were exposed for 6 h to one of four treatments: (1) control, (2) cyclic mechanical stretch, (3) intermittent electrical stimulation or (4) combination of cyclic mechanical stretch and electrical stimulation. Diaphragmatic contraction force increased from 116 ± 21 mN at the lowest preload level to 775 ± 85 mN at the maximal preload level. After 6 h maximal muscle contraction forces were smallest after non-electrostimulated treatment (control: 81 ± 15 mN, mechanical deflection: 94 ± 12 mN) and largest after electrostimulation treatment (mere electrostimulation: 165 ± 20 mN, combined mechano- and electro-stimulation: 164 ± 14 mN). We conclude that our model allows force measurements on isolated rat diaphragms. Furthermore, we conclude that by intermediate electrical stimulation diaphragmatic force generation was better preserved than by mechanical stimulation.
Division for Experimental Anaesthesiology, University Medical Center Freiburg, Freiburg, Germany. caroline.armbruster@uniklinik-freiburg.de
Caroline
C
Armbruster
Constanze
C
Dassow
Katharina
K
Gamerdinger
Matthias
M
Schneider
Migle
M
Sumkauskaite
Josef
J
Guttmann
Stefan
S
Schumann
D000818:Animals; D001696:Biomechanical Phenomena / Q000502:physiology; D016207:Cytokines / Q000378:metabolism; D003964:Diaphragm / Q000000981:diagnostic imaging / Q000502:physiology*; D004558:Electric Stimulation; D005740:Gases; D066298:In Vitro Techniques; D008297:Male; D008954:Models, Biological; D011312:Pressure; D051381:Rats; D017208:Rats, Wistar; D013314:Stress, Mechanical; D013347:Subcellular Fractions / Q000378:metabolism; D014057:Tomography, X-Ray Computed; D016474:Weight-Bearing / Q000502:physiology
D016207:Cytokines; D005740:Gases