Redox states of type 1 ryanodine receptor alter Ca²⁺ release channel response to modulators

Abstract

The type 1 ryanodine receptor (RyR1) from rabbit skeletal muscle displayed two distinct degrees of response to cytoplasmic Ca2+ [high- and low-open probability ( P o) channels]. Here, we examined the effects of adenine nucleotides and caffeine on these channels and their modulations by sulfhydryl reagents. High- P o channels showed biphasic Ca2+ dependence and were activated by adenine nucleotides and caffeine. Unexpectedly, low- P o channels did not respond to either modulator. The addition of a reducing reagent, dithiothreitol, to the cis side converted the high- P o channel to a state similar to that of the low- P o channel. Treatment with p-chloromercuriphenylsulfonic acid (pCMPS) transformed low- P o channels to a high- P o channel-like state with stimulation by β,γ-methylene-ATP and caffeine. In experiments under redox control using glutathione buffers, shift of the cis potential toward the oxidative state activated the low- P ochannel, similar to that of the high- P o or the pCMPS-treated channel, whereas reductive changes inactivated the high- P o channel. Changes in transredox potential, in contrast, did not affect channel activity of either channel. In all experiments, channels with higher P o were stimulated to a great extent by modulators, but ones with lower P o were unresponsive. These results suggest that redox states of critical sulfhydryls located on the cytoplasmic side of the RyR1 may alter both gating properties of the channel and responsiveness to channel modulators.

Effects of organ culture on arterial gene expression and hypoxic relaxation: role of the ryanodine receptor

“…Additionally, the redox status of RyR, which is possibly influenced by decreased PO 2 , can alter Ca 2ϩ release (16). One hypothesis from this investigation is that an increase in RyR expression could lead to altered hypoxia-induced Ca 2ϩ sparks and saturation of any oxygen-sensitive hyperpolarization response.…”

Glucosylceramide and Glucosylsphingosine Modulate Calcium Mobilization from Brain Microsomes via Different Mechanisms

“…*, p Ͻ 0.01. Recent studies have demonstrated that RyaR activity can be enhanced by its redox state (45)(46)(47). Preincubation with the reducing agent, DTT, completely abolished the ability of C8-GlcCer (Fig.…”

A Transverse Tubule NADPH Oxidase Activity Stimulates Calcium Release from Isolated Triads via Ryanodine Receptor Type 1 S -Glutathionylation

“…Skeletal RyR1 channels have a few cysteine residues highly responsive to oxidative modification at physiological pH (65), a property that makes them likely candi- dates to act as intracellular redox sensors (66,67). In vitro experiments indicate that oxidation/alkylation, S-nitrosylation (38,68), or S-glutathionylation (38,62) of RyR1 hyperreactive SH residues enhances channel activity, whereas reduction to their free sulfhydryl state has the opposite effect (67)(68)(69)(70)(71)(72). In particular, incubation of isolated SR vesicles with superoxide anion or H 2 O 2 promotes RyR activation (42,(73)(74)(75).…”