Responses of beta-adrenoceptor in rat soleus to phosphorus compound levels and/or unloading

Ohira, Yoshinobu; Saito, Kazuto; Wakatsuki, Toru; Yasui, Wataru; Suetsugu, Tetsuro; Nakamura, Kaworu; Tanaka, Hirokazu; Asakura, Tetsuhiko

doi:10.1152/ajpcell.1994.266.5.c1257

Cited by 18 publications

(17 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…muscles of ␤-GPA-fed rats were lower than in the control rats, as reported previously [6,[10][11][14][15][16][17][18]. In contrast, high-energy phosphate levels were elevated in the creatine-fed group.…”

Section: Discussionsupporting

confidence: 84%

“…The specific SDH activities for each fiber type in both the soleus and the EDL muscles tended to be elevated by ␤-GPA feeding. This tendency for an increase in the mitochondrial enzyme activity of single muscle fibers, combined with an increase in the percentage of slow fibers, is consistent with the enzymatic adaptations seen in whole homogenates of both predominantly fast and predominantly slow muscles [11,14,16,18,21]. Although the activities of most of the glycolytic enzymes are reduced in these muscles [18,21], resting glucose uptake [34] and GLUT-4 glucose transporter expression [18] are increased.…”

Section: Discussionsupporting

confidence: 79%

“…These results were compared with the data obtained by using 31 P-NMR in the present study, since the data from the in vivo 31 P-NMR analyses may represent values for the gastrocnemius and not necessarily for the soleus, which is located in the deep (close to the bone) region of calf. The responses of the phosphorus compounds to changes in creatine content were similar for both analyses [16]; thus, the non-invasive 31 P-NMR procedures were used in the present study. Furthermore, the responses of the high-energy phosphate levels following the depletion and/or loading of creatine were identical for the plantarflexors and dorsiflexors.…”

Section: Methodsmentioning

confidence: 88%

“…Two days after the EMG recordings, the high-energy phosphate levels in the resting right calf muscles were estimated by using 31 P-nuclear magnetic resonance ( 31 P-NMR) spectroscopy (BEM 170/200, Otsuka Electronics, Osaka, Japan), as described elsewhere [11,16]. In a previous study [16], the soleus and the lateral gastrocnemius muscles from rats treated similarly were freeze-clamped with a pair of aluminum tongs cooled in liquid nitrogen, and the high-energy phosphate levels were measured biochemically [19,[27][28][29]. These results were compared with the data obtained by using 31 P-NMR in the present study, since the data from the in vivo 31 P-NMR analyses may represent values for the gastrocnemius and not necessarily for the soleus, which is located in the deep (close to the bone) region of calf.…”

Section: Methodsmentioning

confidence: 99%

See 3 more Smart Citations

Metabolic Modulation of Muscle Fiber Properties Unrelated to Mechanical Stimuli

Ohira

Kawano

Roy

et al. 2003

JJP

View full text Add to dashboard Cite

Section: Discussionsupporting

confidence: 84%

Section: Discussionsupporting

confidence: 79%

Section: Methodsmentioning

confidence: 88%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Metabolic Modulation of Muscle Fiber Properties Unrelated to Mechanical Stimuli

Ohira

Kawano

Roy

et al. 2003

JJP

View full text Add to dashboard Cite

“…Therefore, it is positively correlated with mitochondrial enzyme activities [72][73][74]. The dominant subtype of ␤-adrenoceptors was ␤ 2 [75], and the maximum binding capacity (B max ) in soleus muscle was decreased following unloading (Fig. 3).…”

mentioning

confidence: 93%

Neuromuscular Adaptation to Microgravity Environment.

Ohira

2000

JJP

View full text Add to dashboard Cite

The pattern of muscle activity influences the morphological, metabolic, and contractile properties of skeletal muscles. For example, the metabolic capacity of muscles is affected specifically by the type of exercise training [1][2][3]. Increased activity or over-loading by removing the synergists causes a compensatory hypertrophy [4][5][6][7][8][9][10][11]. Hypertrophy is also induced by the stretching of matured muscles in vivo [12,13] and cultured myotubes and fibroblasts [14][15][16][17]. Exercise-induced metabolic adaptation of muscles is lost when exercise training is stopped [18]. Further, muscle atrophy is induced by denervation [10,19], spinal cord transection [20], joint immobilization [21][22][23], tenotomy [24,25], spaceflight [26][27][28][29], and/or hindlimb suspension [29][30][31][32]. Most of these models are generally presumed to be models of reduced neuromuscular activity. But the level of use may not be the only factor involved in the atrophic process.There is a close association in the physiological, biochemical, and morphological properties between a motoneuron and the muscle fibers it innervates [1]. Studies to support this view are those in which chronic electrical stimulation at low frequency (1-10 Hz) changes the properties of fast-twitch muscles toward those of slow-twitch muscles [33][34][35][36][37][38].Some of the characteristics of muscle fibers are also altered following cross-innervation [39][40][41][42]. Buller et al. [40] suggested that the neural influence on muscle could be due to neurotrophic effect as well as via nerve impulses. Muscular Responses to Gravitational Unloading Morphological propertiesGravitational unloading by exposure to weightlessness [26][27][28][29][43][44][45][46][47] and/or its simulation model, hindlimb suspension [29][30][31][32][48][49][50][51][52][53][54][55][56], causes rapid atrophy in muscles, such as soleus and adductor longus, that are composed predominantly of slow fibers. The cross-sectional areas (CSAs) of both slow-and fasttwitch fibers of rats were less after 14 d of spaceflight and hindlimb suspension than those in the agematched controls [29]. But the degree of atrophy was greater in slow-than fast-twitch fibers [28,29]. Therefore, muscles composed of predominantly slow fibers are more susceptible to atrophy [26,28, 47]. The weights of fast-twitch ankle dorsi-flexors, such as the tibialis anterior (TA) and extensor digitorum longus (EDL), are also generally less after unloading than those of age-matched controls [31, 57]. But these were Japanese Journal of Physiology, 50, 303-314, 2000 Key words: atrophy, fiber-type transformation, contractile properties, neural responses, microgravity.Abstract: Morphological and/or functional characteristics of skeletal muscles have a greater adaptability in response to changes in environmental stimuli. For example, an atrophy associated with a shift of fiber characteristics toward fast-twitch type is a common adaptation of antigravity muscle to a microgravity environment. Neuromuscular responses and ...

show abstract