Enzymatic responses and adaptations to swimming training and hypobaric hypoxia in postnatal rats.

Abstract

Twenty four male Sprague-Dawley rats, 35 days old, were randomly assigned to one of four groups : 2 resting control groups and 2 swimming groups. The sea level-control and the sea level-swimming groups were housed 5 weeks at 1,011 hPa (760 mmHg) while the hypoxic control and swimming groups were housed for 1 week at 678 hPa, followed by 4 weeks at 611 hPa. The swimming rats were subjected to a swimming program of 30 min, 6 days/week for 5 weeks. Both hypoxia groups developed significantly higher Hb and Hct levels than the sea level groups. The glycogen content in the extensor digitorum longus (EDL) and the deep portion of the vastus lateralis (DVL) muscles of the sea levelswimming group were significantly greater as compared to the hypoxia swimming group. The succinate dehydrogenase (SDH) activity in the sea level-control group was significantly lower in the EDL muscle than in the 3 other groups, and in the DVL muscle lower than that of the sea levelswimming group. Histochemically, hypoxia and swimming training induced significant increases in the fast-twitch-oxidative-glycolytic (FOG) fibers (6-11 %) in soleus muscle, and decreases in the slow-twitch-oxidative (SO) fibers. The EDL muscles had significantly higher percentages of FOG fibers in the hypoxia and swimming groups than in the sea level control group. On the basis of the present study it seems probable that hypoxia is a triggering factor for the conversions of muscle fiber types and the increase in oxidative capacity.

Effect of a carbohydrate supplement on feeding behaviour and exercise in rats exposed to hypobaric hypoxia

“…Vats et al, 1999, found increased liver glycogen by day 1 of exposure and subsequently, decreased liver glycogen towards the end of a 21-day exposure period along with decreased glycogen synthetase activity. The altitude-induced decrease in muscle glycogen is consistent with results of previous studies (Blume & Pace, 1967;Taguchi et al, 1985;Bigard et al, 1996). Bigard et al (1996) demonstrated that glycogen stores in the muscle, particularly soleus, were altered by both decreased energy intake and hypoxia per se.…”

Microvascular Remodelling after Endurance Training with Co2+ Treatment in the Rat Diaphragm and Hind-Leg Muscles.

“…This result raises the possibility that fiber type transformation occurs, at least partially, via a cellular oxygen-sensing mechanism. After chronic exposure to a hypoxic atmosphere, some studies did not observe any significant differences in fiber composition of the SOL [24][25][26], whereas others reported fiber type transformation of slow-twitch (SO) fibers into fast-oxidative-glycolytic (FOG) fibers in the same muscle [27].…”

Immunohistochemical analysis of MCT1, MCT2 and MCT4 expression in rat plantaris muscle

“…Muscle samples frozen for histochemical analyses were sectioned (10 μm thick) in a cryostat at −20°C. The sections were stained for myosin adenosine triphosphatase (ATPase), succinate dehydrogenase (SDH), and α‐glycerophosphate dehydrogenase (α‐GPD) according to previous studies (Wattenberg & Leong, 1960; Taguchi et al 1985).…”