Effects of procaine and caffeine on calcium release from the sarcoplasmic reticulum in frog skeletal muscle.

Abstract

fibres and in the presence of 1 mm-procaine plus 0-5 mm-caffeine. 6. In the presence of 0-5 mM-caffeine A[Ca2+] after 10-20 ms voltage steps exhibited an increase in the time to peak and a slower decay time course compared with caffeine-free controls, suggestive of significant calcium-induced calcium release in the presence of caffeine. These effects of caffeine were completely and reversibly blocked by 1 mM-procaine. 7. In the absence of caffeine, 1 mM-procaine caused a small decrease in time to peak of A[Ca2+] after 10-30 ms duration voltage steps compared to the bracketing control and wash runs without procaine. Rrei turned off faster after 10 ms pulses in procaine than in the absence of procaine, but the turn-off of release was about equally fast with or without procaine after pulses of 20 ms or longer. The effect of procaine 8. The absence of a significant effect of procaine on the Rrel waveform and voltage dependence for long pulses suggests that the major component of suppression of release by procaine may be a non-specific block of SR calcium-release channels.

Suppression of calcium release by calcium or procaine in voltage clamped rat skeletal muscle fibres.

“…In view of our findings it seems unlikely that any calcium release that is activated by solution change depolarization of peeled mammalian fibres in the presence of 10 mm procaine (Donaldson, 1985(Donaldson, , 1986 could be related to the faster calcium release activated by voltage clamp (or action potential) depolarization of mammalian fibres. Our results also indicate that rat fibres were more sensitive than frog fibres to procaine, since the maximum concentration that we could use was 0 3 mM, whereas in similar experiments, frog fibres could tolerate concentrations of 1 mm or more (Klein et al 1992). Nevertheless, we believe that the effect of procaine we observed here was not due to toxicity of the anaesthetic because the transient was at least partially recovered after washout of the drug in three fibres and fully recovered in the fourth fibre.…”

“…In an attempt to investigate whether the entire release or one of its components could be blocked completely, we tested higher concentrations of procaine (0 5 mm in two fibres and 1 mm in one) as used in frog muscle experiments (Klein et al 1992), but the fibres showed an immediate increase of leak current which was not reversible, indicating that rat fibres may be more sensitive to procaine than are frog fibres.…”

“…Both the peak and the steady level of the rateof-release were inhibited by about 50%. Therefore, we are inclined to think that, as in frog fibres (Klein et al 1992), the effect of procaine might be non-specific even at 0 3 mm in voltage clamped rat fibres. In view of our findings it seems unlikely that any calcium release that is activated by solution change depolarization of peeled mammalian fibres in the presence of 10 mm procaine (Donaldson, 1985(Donaldson, , 1986 could be related to the faster calcium release activated by voltage clamp (or action potential) depolarization of mammalian fibres.…”

Properties of Ca2+ release induced by clofibric acid from the sarcoplasmic reticulum of mouse skeletal muscle fibres

“…While 10 mM procaine was reported not to inhibit PCR (Thorens & Endo, 1975;Donaldson, 1985), it was also reported that procaine inhibits PCR in both amphibian and mammalian ®bres (Klein et al, 1992;Garcia & Schneider, 1995). However, even in the report that procaine inhibits PCR, the inhibitory eect of procaine on CICR appears stronger than that on PCR: while 60% of PCR remained, CICR was abolished in the presence of 1 mM procaine (Klein et al, 1992). Clof-induced Ca 2+ release in the absence of Ca 2+ was not inhibited by procaine (Figure 6).…”

Cholinergic regulation of body-wall muscle contraction of the ascidian Styela rustica (Linnaeus, 1767)

“…The suppression of muscle fiber contractile activ ity by procaine is mediated by the blocking of the volt age sensitive sodium channels and the suppression of calcium release from the sarcoplasmic reticulum (via ryanodine receptors) [8,14,16,27]. Procaine was found to block voltage sensitive calcium channels merely to a very low degree [28].…”