{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,11]],"date-time":"2026-06-11T18:54:44Z","timestamp":1781204084095,"version":"3.54.1"},"reference-count":56,"publisher":"MDPI AG","issue":"21","license":[{"start":{"date-parts":[[2025,11,5]],"date-time":"2025-11-05T00:00:00Z","timestamp":1762300800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100004742","name":"National Academy of Sciences of Ukraine","doi-asserted-by":"crossref","award":["0118U007344"],"award-info":[{"award-number":["0118U007344"]}],"id":[{"id":"10.13039\/501100004742","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Calcium (Ca2+) release from the sarcoplasmic reticulum is central to excitation\u2013contraction coupling and plays a critical role in the development of skeletal muscle fatigue. Altered Ca2+ dynamics may affect not only contractile function but also neuromuscular excitability. This study examined the effects of pharmacological modulation of Ca2+ channels on fatigue development and spinal reflex activity in rats. Using the Hoffmann reflex (H-reflex) as an indicator of motoneuron excitability, we evaluated the effects of Ca2+ channel blockers (Amiloride, Nifedipine) and an activator ((\u2212)-Bay K8644) on the reflex responses of the plantar muscle before and after fatigue induction. The ratio of the maximum H-reflex to maximum M-wave (Hmax\/Mmax) was used to assess alterations in spinal excitability. Compared with the control, both Amiloride and Nifedipine markedly reduce the Hmax\/Mmax ratio (77% and 60%, respectively), whereas (\u2212)-Bay K8644 elicited a robust 129% increase. These findings demonstrate that pharmacological modulation of Ca2+ channels has distinct and divergent effects on spinal excitability during fatigue. These results highlight the close interaction between intramuscular Ca2+ regulation and reflex pathways and suggest potential strategies for enhancing muscle performance through targeted Ca2+ channel modulation.<\/jats:p>","DOI":"10.3390\/ijms262110749","type":"journal-article","created":{"date-parts":[[2025,11,5]],"date-time":"2025-11-05T13:19:29Z","timestamp":1762348769000},"page":"10749","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Divergent Effects of Calcium Channel Modulators on H-Reflex Excitability in Fatigued Rat Muscle"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2312-4412","authenticated-orcid":false,"given":"Andriy","family":"Maznychenko","sequence":"first","affiliation":[{"name":"Department of Physical Education, Gdansk University of Physical Education and Sport, Kazimierza Gorskiego Str. 1, 80-336 Gdansk, Poland"},{"name":"Department of Movement Physiology, Bogomoletz Institute of Physiology NAS of Ukraine, Bogomoletz Str. 4, 01024 Kyiv, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5160-4707","authenticated-orcid":false,"given":"Tetiana I.","family":"Abramovych","sequence":"additional","affiliation":[{"name":"Department of Physical Education, Gdansk University of Physical Education and Sport, Kazimierza Gorskiego Str. 1, 80-336 Gdansk, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5312-5462","authenticated-orcid":false,"given":"Nataliya V.","family":"Bulgakova","sequence":"additional","affiliation":[{"name":"Department of Movement Physiology, Bogomoletz Institute of Physiology NAS of Ukraine, Bogomoletz Str. 4, 01024 Kyiv, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7145-9957","authenticated-orcid":false,"given":"Vasyl","family":"Melenko","sequence":"additional","affiliation":[{"name":"Department of Spinal Surgery, State Institution \u201cInstitute of Traumatology and Orthopedics\u201d, National Academy of Medical Science of Ukraine, Bulvarno-Kudriavska Str. 27, 01054 Kyiv, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-6598-5667","authenticated-orcid":false,"given":"Yuliia A.","family":"Levchuk","sequence":"additional","affiliation":[{"name":"Surgery Department, Municipal Nonprofit Enterprise \u201cKyiv City Clinical Hospital #4\u201d, Solomyanska Str. 17, 03110 Kyiv, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0598-8391","authenticated-orcid":false,"given":"Tatyana","family":"Shevchuk","sequence":"additional","affiliation":[{"name":"Anatomy Department, Lesia Ukrainka Volyn National University, Voli Ave. 13, 43025 Lutsk, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9666-1839","authenticated-orcid":false,"given":"Inna","family":"Sokolowska","sequence":"additional","affiliation":[{"name":"Department of Physical Education, Gdansk University of Physical Education and Sport, Kazimierza Gorskiego Str. 1, 80-336 Gdansk, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5109-7303","authenticated-orcid":false,"given":"Alexander I.","family":"Kostyukov","sequence":"additional","affiliation":[{"name":"Department of Movement Physiology, Bogomoletz Institute of Physiology NAS of Ukraine, Bogomoletz Str. 4, 01024 Kyiv, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,11,5]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1725","DOI":"10.1152\/physrev.2001.81.4.1725","article-title":"Spinal and supraspinal factors in human muscle fatigue","volume":"81","author":"Gandevia","year":"2001","journal-title":"Physiol. 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