0000000000362361

AUTHOR

Michael Londershausen

Characterization of a Ryanodine Receptor inPeriplaneta Americana

Specific binding sites for the alkaloid ryanodine were characterized in membrane preparations from sarcoplasmatic reticulum of Periplaneta americana skeletal muscle. Binding of [3H]ryanodine was optimal at pH 8 and at CaCl2 concentration of about 300 mumol l-1. The Ca-chelating agents EGTA (100 mumol l-1) and EDTA (100 mumol l-1) abolished 95% and 90% of the [3H]ryanodine binding respectively. Preincubation with Ca2+ (100 mumol l-1) restored the ryanodine binding in presence of up to 300 mumol l-1 EGTA. Radioligand binding experiments showed one class of high affinity binding sites for ryanodine. Determination of rate constants revealed 7.05 x 10(6) l mol-1 min-1 for associating and 3.77 x …

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Binding Sites for Ca2+‐Channel Effectors and Ryanodine inPeriplaneta americana—Possible Targets for New Insecticides

The calcium channel and the 'calcium release channel' of muscle membrane of the cockroach Periplaneta americana have been characterized. Biological assays with calcium channel blockers and ryanodine on different insects and acari revealed pronounced insecticidal effects with ryanodine, but not with calcium channel blockers, at concentrations between 0.1 and 300 μg ml -1 . Skeletal muscle membranes derived either from the tubular network or from the sarcoplasmatic reticulum of P. americana were characterized with respect to the binding of the dihydropyridine (DHP) [ 3 H]isradipine (PN 200-110), the phenylalkylamine [ 3 H]verapamil and the alkaloid [ 3 H]ryanodine. Preliminary binding studies…

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