Abstract

Vitamin D deficiency, which is highly prevalent in the general population, exerts similar deleterious effects on skeletal muscles to those induced by cigarette smoking. We examined whether cigarette smoke (CS) exposure and/or vitamin D deficiency impairs the skeletal muscle hypertrophic response to overload. Male C57Bl/6JolaH mice on a normal or vitamin D-deficient diet were exposed to CS or room air for 18 wk. Six weeks after initiation of smoke or air exposure, sham surgery or denervation of the agonists of the left plantaris muscle was performed. The right leg served as internal control. Twelve weeks later, the hypertrophic response was assessed. CS exposure instigated loss of body and muscle mass, and increased lung inflammatory cell infiltration (P < 0.05), independently of diet. Maximal exercise capacity, whole body strength, in situ plantaris muscle force, and key markers of hypertrophic signaling (Akt, 4EBP1, and FoxO1) were not significantly affected by smoking or diet. The increase in plantaris muscle fiber cross-sectional area in response to overload was attenuated in vitamin D-deficient CS-exposed mice (smoking × diet interaction for hypertrophy, P = 0.03). In situ fatigue resistance was elevated in hypertrophied plantaris, irrespective of vitamin D deficiency and/or CS exposure. In conclusion, our data show that CS exposure or vitamin D deficiency alone did not attenuate the hypertrophic response of overloaded plantaris muscles, but this hypertrophic response was weakened when both conditions were combined. These data suggest that current smokers who also present with vitamin D deficiency may be less likely to respond to a training program.NEW & NOTEWORTHY Plantaris hypertrophy caused by compensatory overload after denervation of the soleus and gastrocnemius muscles showed increased mass and fiber dimensions, but to a lesser extent when vitamin D deficiency was combined with cigarette smoking. Fatigue resistance was elevated in hypertrophied plantaris, irrespective of diet or smoking, whereas physical fitness, hypertrophic markers, and in situ plantaris force were similar. These data showed that the hypertrophic response to overload is attenuated when both conditions are combined.

Highlights

  • For several decades, cigarette smoking has remained a major avoidable public health hazard as $20% of adults worldwide are active cigarette smokers [1]

  • This study examined for the first time whether cigarette smoking and/or vitamin D deficiency affect the hypertrophic response of skeletal muscle to overload in mice

  • Our data reveal that cigarette smoke (CS) exposure or vitamin D deficiency alone did not attenuate muscle fiber hypertrophy in the overloaded plantaris, but this response was reduced in vitamin D-deficient CS-exposed mice

Read more

Summary

Introduction

Cigarette smoking has remained a major avoidable public health hazard as $20% of adults worldwide are active cigarette smokers [1]. In humans and animal models, chronic cigarette smoking has been associated with skeletal muscle weakness and atrophy, impaired mitochondrial function, reduced vasodilation, decreased perfusion, and diminished fatigue resistance [6, 9,10,11]. It occurs mainly in response to resistance exercise training in humans [14, 15] and in animal models by exercise training, overloading a muscle via denervation [16,17,18,19,20,21,22,23], or elimination of Submitted 25 August 2020 / Revised May 2021 / Accepted May 2021 http://www.jap.org

Objectives
Methods
Results
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call