Regulation of contraction kinetics in skinned skeletal muscle fibers by calcium and troponin C

Decreased intracellular [Ca2+ ] coincides with reduced expression of Dhprα1s, RyR1, and diaphragmatic dysfunction in a rat model of sepsis

INTRODUCTION

Sepsis can cause decreased diaphragmatic contractility. Intracellular calcium as a second messenger is central to diaphragmatic contractility. However, changes in intracellular calcium concentration ([Ca²⁺ ]) and the distribution and co-localization of relevant calcium channels [dihydropyridine receptors, (DHPRα1s) and ryanodine receptors (RyR1)] remain unclear during sepsis. In this study we investigated the effect of changed intracellular [Ca²⁺ ] and expression and distribution of DHPRα1s and RyR1 on diaphragm function during sepsis.

METHODS

We measured diaphragm contractility and isolated diaphragm muscle cells in a rat model of sepsis. The distribution and co-localization of DHPRα1s and RyR1 were determined using immunohistochemistry and immunofluorescence, whereas intracellular [Ca²⁺ ] was measured by confocal microscopy and fluorescence spectrophotometry.

RESULTS

Septic rat diaphragm contractility, expression of DHPRα1s and RyR1, and intracellular [Ca²⁺ ] were significantly decreased in the rat sepsis model compared with controls.

DISCUSSION

Decreased intracellular [Ca²⁺ ] coincides with diaphragmatic contractility and decreased expression of DHPRα1s and RyR1 in sepsis. Muscle Nerve 56: 1128-1136, 2017.