1999 Fiscal Year Final Research Report Summary
A study on mechanism related to enhanced glucose transport by elevated CaィイD12+ィエD1 concentration during contraction of skeletal muscle
| Project/Area Number |
09480017
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
体育学
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| Research Institution | National Institute of Fitness and Sports (1999)
National Institute of Health and Nutrition (1997-1998) |
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Principal Investigator |
TABATA Izumi National Institute of Fitness and Sports, Department of Physiology and Biomechanics, Professor, 体育学部, 教授 (20188402)
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| Project Period (FY) |
1997 – 1999
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| Keywords | muscle contraction / calcium / skeletal muscle / glucose metabolism |
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| Research Abstract |
Firstly, we have developed a method for measuring cytosol CaィイD12+ィエD1 concentration in mammal skeletal muscle tissue. Changes in CaィイD12+ィエD1 concentration was estimated using double-beam fluorescent method with fura-2/AM as a fluorescent indicator which penetrates into cytosol of skeletal muscle (emittion: 340 nm and 380 nm, fluorescent 500 nm). Using a small and thin forelimb muscle named epitrochlearis from rat weighing 100-110 g, CaィイD12+ィエD1 concentration in the muscle was evidenced to be measured during long-term incubation and submaximal contraction. However, during tetani contractions, CaィイD12+ィエD1 concentration was not found to be measured due to artifact related to tenani.
Since recent studies suggested that stimulated glucose transport activity by contraction is related to increased CaィイD12+ィエD1 concentration in skeletal muscle, we observed effects of physiological stimuli including insulin, submaximal contraction, and submaximal hypoxia that do not induce tetani, and pharma
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cological stimuli that affect CaィイD12+ィエD1 concentration in cell.
We firstly observed elevation of CaィイD12+ィエD1 in the muscle during incubation with low concentration caffeine (3 mM), W-7(50μM), and submaximal hypoxia. As these stimuli are known to increase glucose transport activity in the muscle, we think that the method is valid and valuable to clarify mechanisms related to submaximal contraction-stimulated glucose transport activity in rat skeletal muscle.
There was no change in CaィイD12+ィエD1 during incubation in AICAR known to stimulate AMP kinase that may intervene muscle-contraction induced increase in glucose transport activity. This result suggests that pathway related to CaィイD12+ィエD1 -enhanced glucose transport activity does not exist prior to AMP kinase.
Insulin has been shown not to affect CaィイD12+ィエD1 level in the muscle until 20 min after initiation of incubation. However, we observed that CaィイD12+ィエD1 concentration did increase after 20 min incubation in insulin (2 mU/ml). This result may suggest that this method can also be used for the purpose of elucidating insulin-induced glucose transport activity in skeletal muscle. Less
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