TY - JOUR
T1 - Responses of Contractile Properties in Rat Soleus to High-Energy Phosphates and/or Unloading
AU - Wakatsuki, T.
AU - Ohira, Y.
AU - Yamamoto, M.
AU - Yasui, W.
AU - Nakamura, K.
AU - Asakura, T.
AU - Ohno, H.
PY - 1994
Y1 - 1994
N2 - Responses of contractile properties of soleus to unloading and/or changes in high-energy phosphate contents were studied in rats. Reduction of high-energy phosphates, especially phosphocreatine, in ankle extensors was induced by feeding β-guanidinopropionic acid (β-GPA). The major finding in the study was that the fatigability and speed-related contractile properties responded to unloading and creatine supplementation in a similar manner. The high-energy phosphate contents tended to be elevated after 10-d supplementation of creatine and hindlimb suspension. The shift toward slow-type, mainly due to an increased one-half relaxation time, was seen in rats fed β-GPA. Such a shift was reversed by feeding creatine or by hindlimb suspension; however, the suspension-induced shift of contractile properties toward fast-type was not prevented completely by β-GPA feeding. Although the muscle fatigue resistance did not change by β-GPA feeding alone, the decrease in fatigue resistance following suspension and creatine supply was less in the β-GPA group. It is suggested that the levels of high-energy phosphates and tension production play important roles in the regulation of contractile properties of the soleus muscle.
AB - Responses of contractile properties of soleus to unloading and/or changes in high-energy phosphate contents were studied in rats. Reduction of high-energy phosphates, especially phosphocreatine, in ankle extensors was induced by feeding β-guanidinopropionic acid (β-GPA). The major finding in the study was that the fatigability and speed-related contractile properties responded to unloading and creatine supplementation in a similar manner. The high-energy phosphate contents tended to be elevated after 10-d supplementation of creatine and hindlimb suspension. The shift toward slow-type, mainly due to an increased one-half relaxation time, was seen in rats fed β-GPA. Such a shift was reversed by feeding creatine or by hindlimb suspension; however, the suspension-induced shift of contractile properties toward fast-type was not prevented completely by β-GPA feeding. Although the muscle fatigue resistance did not change by β-GPA feeding alone, the decrease in fatigue resistance following suspension and creatine supply was less in the β-GPA group. It is suggested that the levels of high-energy phosphates and tension production play important roles in the regulation of contractile properties of the soleus muscle.
UR - http://www.scopus.com/inward/record.url?scp=0028200729&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0028200729&partnerID=8YFLogxK
U2 - 10.2170/jjphysiol.44.193
DO - 10.2170/jjphysiol.44.193
M3 - Article
C2 - 7967221
AN - SCOPUS:0028200729
SN - 0021-521X
VL - 44
SP - 193
EP - 204
JO - Japanese Journal of Physiology
JF - Japanese Journal of Physiology
IS - 2
ER -