Key result
Ryanodine (0.1-10 nM) reduced rest potentiation in a dose-dependent manner and accelerated rest depression of both twitch force and cold contracture force in rat cardiac trabeculae.
Ryanodine in the nanomolar range promotes Ca2+ leak from the sarcoplasmic reticulum in rat cardiac trabeculae, causing a negative inotropic effect due to SR Ca2+ depletion rather than blocking Ca2+ release channels.
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Ryanodine effects on cardiac force remain preclinical; leaves open translation to human SR Ca2+ handling.
Banijamali et al. (1991) studied this question. Ryanodine vs. Control conditions was evaluated on Force-interval relations of twitches (Ft) and cold contractures (Fc). Ryanodine (0.1-10 nM) reduced rest potentiation in a dose-dependent manner and accelerated rest depression of both twitch force and cold contracture force in rat cardiac trabeculae.
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