Effect of Food Restriction on Biorhythm

研究了限食对生物节律的影响。以钙激活蛋白酶（CAF）及其内源性抑制剂（CAF抑制剂）的活性作为最大限食条件下的生物节律变化指标。用从兔骨骼肌中提取的CAF粗品研究了CAF对饥饿的钙敏感性变化。饥饿组大鼠背最长肌CAF总活性显著高于进食组（P<0.01）。另一方面，CAF抑制剂活性在实验期间变化不大。因此，CAF可能在肌原纤维蛋白降解中起重要作用。对照组和饥饿1天组大鼠在钙浓度低于1 mM时几乎检测不到粗CAF活性，而饥饿2天以上组在钙浓度低于1 mM时CAF制剂被充分激活。这些结果表明，在饥饿条件下，高钙型CAF（H-CAF）转化为低钙型CAF（L-CAF）或L-CAF在活细胞中特异性诱导的可能性。

Effect of food restriction on biorhythm was studied. Calcium activated protease(CAF) and its endogeneous inhibitor(CAF inhibitor) activities were used as the indexes of biorhythm changes under stavation, the maximum restriction of food. The changes in calcium sensitivity of CAF in response to starvation were also studied using crude CAF preparations obtained from the skeletal muscle of rars. Total CAF activity in longissimus muscle of back of starved rats significantly increased in comparison with that of fed rats (p<0.01). On the other hand, CAF inhibitor activity had little changed during experimental period. It is therefore suggested that CAF might take an important role in myofibrillar protein degradation in response to starvation. Crude CAF activity was hardly detected in the calcium concentration less than 1 mM in the control group and in the 1 day-starved group rats, however CAF preparation was sufficiently activated in calcium less than 1mM in the groups starved for more 2 days. These results indicate the possibility of the transformation of high calcium required form of CAF (H-CAF) into low calcium required form of CAF (L-CAF) or the specific induction of L-CAF in the living cells during starvation.