Divergent Effects of Calcium Channel Modulators on H-Reflex Excitability in Fatigued Rat Muscle
Year: 2025
Type: article
Abstract: Calcium (Ca2+) release from the sarcoplasmic reticulum is central to excitation–contraction 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 ((−)-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 (−)-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.
Institutions: Bogomoletz Institute of Physiology, Gdansk University of Physical Education and Sport, National Academy of Medical Sciences of Ukraine, State Institution “National Institute of Traumatology and Orthopedics of the National Academy of Medical Sciences of Ukraine”, Lesya Ukrainka Volyn National University
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $3,499
Award: G3706882985
OpenAlex ID: W4415924759