Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA194

Poster Communications

L-arginine ingestion inhibits eccentric contraction-induced proteolysis and force deficit via S-nitrosylation of calpain

K. Kanzaki1, D. Watanabe2, C. Aibara3, Y. Kawakami4, T. Yamada5, Y. Takahashi4, M. Wada3

1. Kawasaki University of Medical Welfare, Kurashiki, Japan. 2. University of Electro-Communications, Chofu, Japan. 3. Hiroshima University, Higashi-hiroshima, Japan. 4. Okayama Prefectural University, Soja, Japan. 5. Sapporo Medical University, Sapporo, Japan.


[Introduction] It has been shown that eccentric contraction (ECC), in which skeletal muscles are stretched while contracting, results in long-lasting force depression, at least partly, through calpain-mediated proteolysis of Ca2+-regulatory proteins (1) and that exogenously applied nitric oxide decreases the calpain-induced proteolysis (2). The aim of this study was to investigate whether ingestion of L-arginine (ARG), a nitric oxide precursor, inhibits ECC-induced proteolysis of Ca2+-regulatory proteins and force deficit by decreasing the proteolytic function of calpain. [Methods] All experimental procedures were approved by the Animal Experimental Committee of Okayama Prefectural University and Hiroshima University. Male Wistar rats (8-9 weeks old) were assigned to a control (CON) or an ARG group (n=7 for each group). The ARG rats were provided water containing 0.3% ARG ad libitum for 7 days starting from 3 days before the ECC protocol (average ingestion 611 mg/kg body wt/day). Under anesthesia by an intraperitoneal injection of a mixture of medetomidine (0.4 mg/kg body wt), midazolam (2.0 mg/kg body wt) and butorphanol (2.5 mg/kg body wt), tibialis anterior (TA) muscles underwent 200 repeated ECCs in situ. The rested muscles of the contralateral legs were used as controls. Three days after ECC, dorsiflexion torque was measured under anesthesia and subsequent biochemical analyses were performed in excised TA muscles. Data are presented as means ± SEM. A two-way ANOVA followed by Holm-Sidak post hoc test was used to examine the statistical significance. [Results] ARG ingestion attenuated ECC-induced force deficit (torque at 20 Hz: 57 ± 3 for CON-rest, 34 ± 3 for CON-ECC, 63 ± 2 for ARG-rest, and 49 ± 2 mNm for ARG-ECC. P < 0.05, CON-ECC vs ARG-ECC) and autolysis of calpain-1 (12 ± 2 for CON-rest, 20 ± 3 for CON-ECC, 11 ± 1 for ARG-rest, and 13 ± 1 % for ARG-ECC, P < 0.05, CON-ECC vs ARG-ECC), and increased the amounts of S-nitrosylated calpain-1 (CON-rest: 100 ± 11, CON-ECC: 142 ± 47, ARG-rest: 245 ± 31, ARG-ECC: 247 ± 34 %; P < 0.05: CON-ECC vs ARG-ECC). ARG ingestion completely inhibited proteolysis of ryanodine receptor (CON-rest: 100 ± 7, CON-ECC: 65 ± 7, ARG-rest: 107 ± 5, ARG-ECC: 93 ± 10 %; P < 0.05: CON-ECC vs ARG-ECC) and dihydropyridine receptor (CON-rest: 100 ± 9, CON-ECC: 60 ± 7, ARG-rest: 97 ± 5, ARG-ECC: 87 ± 7 %; P < 0.05: CON-ECC vs ARG-ECC) and partially inhibited proteolysis of junctophilin-1 (CON-rest: 100 ± 8, CON-ECC: 21 ± 6, ARG-rest: 107 ± 5, ARG-ECC: 51 ± 14 %; P < 0.05: CON-ECC vs ARG-ECC). [Conclusion] These results indicate that ARG ingestion can attenuate ECC-induced proteolysis of Ca2+ regulatory proteins and force deficit by decreasing calpain activation via S-nitrosylation.

Where applicable, experiments conform with Society ethical requirements