Morphofunctional responses to anaemia in rat skeletal muscle

Abstract

Adult male Sprague-Dawley rats were randomly assigned to two groups: control and anaemic. Anaemia was induced by periodical blood withdrawal. Extensor digitorum longus and soleus muscles were excised under pentobarbital sodium total anaesthesia and processed for transmission electron microscopy, histochemical and biochemical analyses. Mitochondrial volume was determined by transmission electron microscopy in three different regions of each muscle fibre: pericapillary, sarcolemmal and sarcoplasmatic. Muscle samples sections were also stained with histochemical methods (SDH and m-ATPase) to reveal the oxidative capacity and shortening velocity of each muscle fibre. Determinations of fibre and capillary densities and fibre type composition were made from micrographs of different fixed fields selected in the equatorial region of each rat muscle. Determination of metabolites (ATP, inorganic phosphate, creatine, creatine phosphate and lactate) was done using established enzymatic methods and spectrophotometric detection. Significant differences in mitochondrial volumes were found between pericapillary, sarcolemmal and sarcoplasmic regions when data from animal groups were tested independently. Moreover, it was verified that anaemic rats had significantly lower values than control animals in all the sampled regions of both muscles. These changes were associated with a significantly higher proportion of fast fibres in anaemic rat soleus muscles (slow oxidative group = 63.8%; fast glycolytic group = 8.2%; fast oxidative glycolytic group = 27.4%) than in the controls (slow oxidative group = 79.0%; fast glycolytic group = 3.9%; fast oxidative glycolytic group = 17.1%). No significant changes were detected in the extensor digitorum longus muscle. A significant increase was found in metabolite concentration in both the extensor digitorum longus and soleus muscles of the anaemic animals as compared to the control group. In conclusion, hypoxaemic hypoxia causes a reduction in mitochondrial volumes of pericapillary, sarcolemmal, and sarcoplasmic regions. However, a common proportional pattern of the zonal distribution of mitochondria was maintained within the fibres. A significant increment was found in the concentration of some metabolites and in the proportion of fast fibres in the more oxidative soleus muscle in contrast to the predominantly anaerobic extensor digitorum longus.

Mitochondrial function in sparrow pectoralis muscle

“…In the IMF sections, closely associated, elongated mitochondria can be seen located between myofibrils (Fig.1B). The calculated IMF mitochondrial volume density in sparrow pectoralis was 25.4±3.3%, approximately five times higher than reported values for the extensively studied rat mixed hindlimb muscle (Esteva et al, 2008;Johnson et al, 1990;Philippi and Sillau, 1994). The determined sparrow pectoralis mitochondrial volume density corroborated a single study that determined English sparrow mitochondrial volume density to be 29.9%.…”

Iron deficiency‐induced loss of skeletal muscle mitochondrial proteins and respiratory capacity; the role of mitophagy and secretion of mitochondria‐containing vesicles

“…From animal models, it is well known that iron deficiency reduces mitochondrial function and content 3‐8 . Moreover, iron deficiency has been shown to have negative effects on exercise capacity and skeletal muscle performance in humans (reviewed in Ref.…”

“…Iron homeostasis is essential for proper mitochondrial function as iron is an essential component for several of the protein complexes that make up the electron transport chain, and hence is essential for cellular respiration and subsequent ATP production. Indeed, it is well established that iron deficiency in vivo results in decreased skeletal muscle mitochondrial quantity and function culminating in impaired oxidative substrate metabolism 3‐8 . Illustrative of its clinical significance, iron deficiency has been associated with muscle weakness and decreased exercise capacity in patients with congestive heart failure and chronic obstructive pulmonary disease 9,10 .…”

Histochemical and ultrastructural changes of sternomastoid muscle in aged wistar rats

“…Analyzing the mitochondrial density in subsarcolemmal, sarcoplasmic (intermyofibrillar), and pericapilar regions of muscle tissue in anemic rats, Esteva et al (2008) observed a reduction in mitochondrial amount in these regions. The authors emphasized that in muscles with different oxidative and glycolytic characteristics, as the extensor digitorum longus and soleus muscles, respectively, it was found these mitochondrial alterations.…”