Activation of Ca2+ release from sarcoplasmic reticulum vesicles by 4-alkylphenols.
4-Alkylphenols induce Ca2+ release from junctional (terminal cisternae) sarcoplasmic reticulum vesicles, but not from nonjunctional sarcoplasmic reticulum vesicles. The 4-alkylphenol concentration required to induce Ca2+ release decreases about threefold for every methylene carbon increase in the alkyl chain length, indicating that the Ca(2+)-releasing potency of 4-alkylphenols is related to their ability to partition into the membrane. The rate and amount of Ca2+ release induced by relatively low 4-octylphenol concentrations (25 nmol/mg protein) are altered by the sarcoplasmic reticulum Ca2+ channel activators, Ca2+ and ATP, and the Ca2+ channel inhibitors, Mg2+ and ruthenium red. Ca2+ release induced by 250 nmol 4-octylphenol/mg protein is much less influenced by Ca2+ channel activators and inhibitors; however, even at this high 4-octylphenol concentration, Ca2+ release is not induced from nonjunctional sarcoplasmic reticulum vesicles. The data indicate that 4-alkylphenols induce Ca2+ release by activating the sarcoplasmic reticulum Ca2+ channel.
Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814.
T J
TJ
Beeler
K S
KS
Gable
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004340:Drug Contamination; D009469:Neuromuscular Junction / Q000378:metabolism*; D010636:Phenols / Q000494:pharmacology*; D051381:Rats; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*
D015220:Calcium Channels; D010636:Phenols; C080417:4-octylphenol; C042291:4-ethylphenol; D000252:Calcium-Transporting ATPases; C041594:4-nonylphenol; D002118:Calcium