At that state the excess amount of [Ca.sup.2+] entering the cytoplasm is not able to be withdrawn from myoplasm
and, subsequently, damages cellular structures.
Type I ryanodine receptors are located in the sarcoplasmic reticulum in close proximity to the L-type channels  and physical coupling between the type I ryanodine receptors and the L-type calcium channels (they either directly or through accessory proteins cause the ryanodine receptors to undergo a conformational change and open releasing calcium into the myoplasm
The inorganic phosphate enters the myoplasm
before moving into the SR, where the [P.sub.i] combines with [Ca.sup.++] to form calcium phosphate (Ca[P.sub.i]).
When the input resistance is measured by double-barreled microelectrode, current [I.sub.o] flows through resistance of the myoplasm
[r.sub.pl], resistance of intercellular contacts [r.sub.k] and resistance of the electrogenic membrane [r.sub.m] (electric diagram in Fig.
Changes in both voluntary and electrically evoked muscle performance during the SSE are likely not to be attributed to an increase in the myoplasm
of metabolites, like phosphate and hydrogen ions, since the duration of the jump (0.5-0.55 s) was too small for ATP and PCr to be decreased significantly while the resting period of 30 s was sufficient for ATP and PCr to be restored.
The discovery of an animal model for malignant hyperthermia, a certain breed of pigs, led to the realisation that the essential biochemistry of malignant hyperthermia was increased calcium in the myoplasm
. In the early 1970s, Kalow and Britt (9,10) showed that muscle samples from affected individuals contracted to a greater extent than normal when exposed to caffeine in vitro.
However, this approach provides direct information only about the small amount of [Ca.sup.2+] that is actually free in the myoplasm
. The total movements of [Ca.sup.2+] can only be estimated by modelling the large quantities of other [Ca.sup.2+] buffers in the cell (e.g., parvalbumin and troponin; 4), but the amounts and the kinetics of these calcium buffers are not always known in detail.
Most muscle cells contain a salt solution, called the myoplasm
, and a storage compartment for calcium, called the sarcoplasmic reticulum.
The B-line presumptive muscle cells of ascidian embryos have extensive potential for self-differentiation dependent on determinants prelocalized in the myoplasm
of fertilized eggs (2).
Normal distributions of myoplasm
were altered in ascidian embryos by using a microcompression technique (Whittaker, 1980).
occulta may be due to the absence of a protein that is recognized by a vertebrate intermediate filament antibody (NN18) localized in the myoplasm