...John James Mackrill ABSTRACT During mammalian cardiomyocyte excitation–contraction coupling, Ca 2+ influx through voltage-gated Ca 2+ channels triggers Ca 2+ release from the sarcoplasmic reticulum (SR) through ryanodine receptor channels. This Ca 2+ -induced Ca 2+ release mechanism controls...

.... It has been suggested that birds use intracellular Ca 2+ stored within the sarcoplasmic reticulum (SR) to power contractile function, but neither SR Ca 2+ content nor the cross-talk between channels underlying Ca 2+ -induced Ca 2+ release (CICR) have been studied in adult birds. Here we used voltage...

... autocrine/paracrine regulation contractility and relaxation Frank–Starling response neuro-humoral modulation sarcoplasmic reticulum transduction cascades The eels (bony fish in the genus Anguilla ) include approximately 18 species that, for their peculiar physiological features, have become...

...Hanna Korajoki; Matti Vornanen SUMMARY In the heart of rainbow trout ( Oncorhynchus mykiss ), the rate of contraction and Ca 2+ uptake into the sarcoplasmic reticulum (SR) are faster in atrial than ventricular muscle, and contraction force relies more on SR Ca 2+ stores after acclimation to cold...

... ), density, and steady-state and maximal sarcoplasmic reticulum (SR) Ca 2+ content (ssSR load and maxSR load ). Current–voltage relations, peak I Ca density and charge density of I Ca were greatest in mackerel and yellowfin at all temperatures tested. I Ca density and kinetics were temperature sensitive...

...Hanna Korajoki; Matti Vornanen SUMMARY Calsequestrin (CASQ) is the main Ca 2+ binding protein within the sarcoplasmic reticulum (SR) of the vertebrate heart. The contribution of SR Ca 2+ stores to contractile activation is larger in atrial than ventricular muscle, and in ectothermic fish hearts...

...). The fatty acid composition of mitochondrial membranes and sarcoplasmic reticulum can be monitored by measuring total muscle phospholipids because all phospholipids are equally affected by diet. Only extreme regimes of endurance training can lead to increments in oxidative capacity matching those induced...

... stimulated and contralateral control muscles were collected and processed for electron microscopy. We used stereological analysis of muscle cross-sections to quantify the volume densities of contractile elements, sarcoplasmic reticulum, mitochondria and intracellular lipids. We found that mitochondrial...

...+ in the sarcoplasmic reticulum was determined by post rest potentiation (PRP). Stimulation of ventricle strips was discontinued for 5 min, prior to PRP measurements. PRP was higher in glucose-treated ventricle strips when compared with the corresponding glucose-free control. Values are means ± s.e.m.( N =6-11 strips...

... . The SBM fibres were rapidly frozen at rest, during contraction and at various times after the onset of relaxation. Changes in calcium distribution in the components of the sarcoplasmic reticulum (SR) were examined on the SBM fibre cryosections. In resting fibres, the calcium concentration was highest...

... to activation of mitochondrial creatine kinase. These results are taken to show strong structural associations (functional complexes) among mitochondria, sarcomeres and sarcoplasmic reticulum. Inside these complexes, mitochondrial functional state is controlled by channeling of ADP, mostly via energy...

.... Bers, D. M. ( 1985 ). Ca influx and sarcoplasmic reticulum Ca release in cardiac muscle activation during post-rest recovery. Am. J. Physiol. 248 , H366 -H381. Bers, D. M. ( 1987 ). Ryanodine and the calcium content of cardiac SR assessed by caffeine and rapid cooling contractures. Am. J...

...Holly A. Shiels; Matti Vornanen; Anthony P. Farrell SUMMARY To explore how the cardiac sarcoplasmic reticulum (SR) functions over a range of temperatures, we used whole-cell voltage clamp combined with rapid caffeine application to study SR Ca 2+ accumulation, release and steady-state content...

... coupling. The possibilities that adrenaline counteracts the effects of high [K + ] via the sarcoplasmic reticulum or sarcolemmal Na + /K + -ATPase were examined by inhibiting the sarcoplasmic reticulum with ryanodine (10 μmol l −1 ) or Na + /K + -ATPase with ouabain (0.25 or 3 mmol l −1 ). No evidence...

... by Company of Biologists 2000 rainbow trout Oncorhynchus mykiss electrophysiology I Ca temperature L-type Ca 2+ channel Ca 2+ cycling sarcoplasmic reticulum Many fish inhabit eurythermal environments and must therefore be able to cope with changes in environmental temperature...

... of the [Ca 2+ ] i transient, cell shortening and action potential with a decrease in the duration of the action potential at both 20 % and 90 % repolarisation. Caffeine was used to assess the Ca 2+ content of the sarcoplasmic reticulum. We observed that sarcoplasmic reticulum Ca 2+ load was greater at 1.0 Hz...

... rate of the sarcoplasmic reticulum (SR) compared with ventricular tissue. Similarly, the faster kinetics of contraction following cold acclimation could be attributed to enhancement of the myofibrillar and/or SR function. The atrio-ventricular and temperature-induced differences were also expressed...

... temperature acclimation fish heart sarcoplasmic reticulum Ca 2+ uptake excitation–contraction coupling thapsigargin Fura-2 rainbow trout crucian carp Carassius carassius Oncorhynchus mykiss Sarcoplasmic reticulum (SR) participates in the contraction and relaxation of cardiac muscle...

...H. A. Shiels; A. P. Farrell ABSTRACT The sarcoplasmic reticulum (SR) is central to intracellular Ca 2+ regulation during excitation–contraction (E-C) coupling in mammalian cardiac tissue. The importance of the SR to E-C coupling in lower vertebrates is less certain. This uncertainty can...

...Marion J. Thomas; Brian N. Hamman; Glen F. Tibbits ABSTRACT In the adult mammalian heart, the majority of Ca 2+ required for contraction is released from the sarcoplasmic reticulum (SR) via the Ca 2+ -release channel or ryanodine receptor (RyR). Such release is dependent upon a relatively small...