..., Python regius , the tegu lizard, Tupinanvis merianae , and the varanid lizard, Varanus exanthematicus . Force-frequency trials and imposed pauses were performed on ventricular and atrial tissue from each species with and without the SR inhibitor ryanodine, and in the absence and presence of adrenaline...

... ) receptor (IP 3 R) and subsequent release of Ca 2+ from the sarcoplasmic reticulum (SR). IP 3 R-mediated release of SR Ca 2+ causes calcium-induced calcium release (CICR) via the ryanodine receptor (RyR), which can be sensitized by cyclic adeninediphosphate ribose (cADPR). cADPR is synthesized from NAD...

... of the inositol trisphosphate (IP 3 ) receptors(IP 3 R), we utilized two inhibitors of the mammalian IP 3 R, TMB-8 and 2-APB. In Ca 2+ -free Ringer, these agents inhibit the response to ET B R agonist stimulation by 71%. The ryanodine-sensitive receptor (RyR) may be activated by low concentrations of ryanodine...

..., increased [Ca 2+ ] i . To assess the participation of inositol triphosphate (IP 3 ) generation, sarcoplasmic/endoplasmic reticulum (SR/ER) Ca 2+ depletion, and activation of store-operated Ca 2+ entry, we utilized thapsigargin and ryanodine to deplete Ca 2+ SR/ER stores and the inhibitory reagents TMB-8...

... °C) fish. The fast recovery of force from inactivation in the heart of the CA trout was, at least in part, due to more active SR. Furthermore, it was shown that the force of atrial contraction in the CA trout is sensitive to ryanodine (10 μmol l −1 ), a Ca 2+ -release channel blocker of SR...

... ) 23 6 1999 25 8 1999 © 1999 by Company of Biologists 1999 ryanodine caffeine contracture Na + /Ca 2+ exchange oxalate-supported calcium uptake Octopus vulgaris Coleoid cephalopods (octopus, cuttlefish and squid) have high metabolic rates and a relatively low oxygen...

...H. A. Shiels; E. V. Freund; A. P. Farrell; B. A. Block ABSTRACT We used an isometric muscle preparation to test the hypothesis that yellowfin tuna Thunnus albacares utilize the intracellular Ca 2+ storage sites of the sarcoplasmic reticulum (SR) during routine contractions. Ryanodine (a blocker...

...+ influx across the sarcolemma (SL) to cardiac performance in rainbow trout Oncorhynchus mykiss . Adrenaline and ryanodine were used to modulate Ca 2+ flux through the SL and SR, respectively. Experiments were conducted at two temperatures (12 °C and 22 °C) (1) to investigate the effect of an acute...

... be attributed, in part, to the temperature-dependency of the SR Ca 2+ -release channel and to interspecific differences in the ryanodine-sensitivity of ectotherm cardiac muscle. Furthermore, the relative importance of the SR in contributing intracellular Ca 2+ to force development may be influenced...

... requires Ca 2+ release from the sarcoplasmic reticulum. Contraction elicited by brief extracellular electrical stimulation was reduced by the removal of Ca 2+ or by the addition of 25 μ mol l −1 nicardipine in crayfish Ringer’s solution. Addition of 30 μ mol l −1 ryanodine with 1mmol l −1 caffeine induced...

... on either component. A single-channel recording suggested that the transient component was carried by a low-conductance channel. Certain compounds with insecticidal action (ryanodine, S-bioallethrin, deltamethrin and avermectin) did not affect calcium channel currents in these cells. These data suggest...

... were also treated with ryanodine to assess the importance of calcium release from the sarcoplasmic reticulum. Ventricle strips from skate and black dogfish showed a five-fold increase in force development when external calcium was raised from a physiological to a saturating level. Force development...