In vitro: |
American Journal of Physiology Cell Physiology, 1987, 253(3):C364-C368. | Ryanodine modifies conductance and gating behavior of single Ca2+ release channel.[Reference: WebLink] | Ryanodine affects excitation-contraction coupling in skeletal and cardiac muscle by specifically interacting with the sarcoplasmic reticulum (SR) Ca2+ release channel.
METHODS AND RESULTS:
The effect of the drug at the single channel level was studied by incorporating skeletal and cardiac SR vesicles into planar lipid bilayers. The two channels were activated by micromolar free Ca2+ and millimolar ATP and inhibited by Mg2+ and ruthenium red.
CONCLUSIONS:
Addition of micromolar concentrations of Ryanodine decreased about twofold the unit conductance of the Ca2+- and ATP-activated skeletal and cardiac channels. A second effect of Ryanodine was to increase the open probability (Po) of the channels in such a way that Po was close to unity under a variety of activating and inactivating conditions.
The effects of Ryanodine were long lasting in that removal of Ryanodine by perfusion did not return the channels into their fully conducting state. | Journal of Agricultural & Food Chemistry, 1998, 46(6):2206-2210. | Multiresidue analytical procedure for insecticides used by organic farmers.[Reference: WebLink] | A multiresidue procedure for the insecticides used by organic farmers has been developed.
METHODS AND RESULTS:
Rotenone, cevadine, and veratridine (the major components of sabadilla), pyrethrin I and pyrethrin II (the major components of pyrethrum), and Ryanodine and dehydroRyanodine (the major components of ryania) can be separated by high-performance liquid chromatography (HPLC) and detected and quantified by atmospheric pressure chemical ionization mass spectrometry (APCI/MS) in the selected ion monitoring mode. Piperonyl butoxide, a material sometimes used together with rotenone or pyrethrum to enhance toxicity, can also be detected and quantified by this procedure. The analytes are extracted with acetonitrile/water and are cleaned up with a C18 solid-phase extraction cartridge. Rotenone, piperonyl butoxide, and the two major sabadilla components could be detected (signal-to-noise ratio = 10) in lettuce, cucumber, and cabbage at 1-6 ppb.
CONCLUSIONS:
Pyrethrin I and the ryania components could be detected between 10 and 171 ppb in these vegetables, whereas pyrethrin II was generally less sensitive, with a limit of detection as high as 200 ppb in cabbage. Recoveries were in the 72-124% range. Percent coefficients of variation ranged from 2 to 17. |
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