Premium
Force‐calcium relationships in intact skeletal muscle: effects of temperature
Author(s) -
Clanton Thomas L
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a943-a
Subject(s) - biophysics , calcium , fluorescence , chemistry , cuvette , skeletal muscle , fluorophore , muscle contraction , stimulation , anatomy , biology , optics , endocrinology , physics , organic chemistry
Force‐Ca +2 relationships measured in isolated skeletal muscle cells are highly quantitative but can result in non‐physiologic artifacts associated with isolation. We have developed a tissue fluorescence method to estimate ΔCa+2 while measuring tetanic force. Mouse hemidiaphragms were mounted in a cuvette that maintained fixed lateral and horizontal displacements and minimal vertical displacements. Muscles were loaded with 5 μM Rhod‐2 AM, a cytosolic Ca +2 sensitive fluorophore. Excitation light was directed at 90° to emission using fiberoptic cables. As expected, low frequency stimulations (<60 Hz) resulted in greater peak forces at 23° C, whereas at 37° C, high frequency forces were elevated. In a given muscle, the relationship between ΔForce/ΔRhod‐2 fluorescence at each stimulation frequency resolved to a single value at > 60 Hz, at both temperatures. In contrast, at < 60 Hz, the same peak Δfluorescence was observed with each contraction at both temperatures but at 37°C smaller changes in force were observed for a given Δ in Rhod‐2 fluorescence. The data confirm that greater high frequency forces generated at 37°C are related to increased calcium release (NHLBI 53333).