Perturbation of myo-inositol-1,4,5-trisphosphate levels during agonist-induced Ca2+ oscillations

Biophysical Journal
J Y ChattonJ W Stucki

Abstract

Agonist-induced Ca2+ oscillations in rat hepatocytes involve the production of myo-inositol-1,4,5-trisphosphate (IP3), which stimulates the release of Ca2+ from intracellular stores. The oscillatory frequency is conditioned by the agonist concentration. This study investigated the role of IP3 concentration in the modulation of oscillatory frequency by using microinjected photolabile IP3 analogs. Photorelease of IP3 during hormone-induced oscillations evoked a Ca2+ spike, after which oscillations resumed with a delay corresponding to the period set by the agonists. IP3 photorelease had no influence on the frequency of oscillations. After photorelease of 1-(alpha-glycerophosphoryl)-D-myo-inositol-4,5-diphosphate (GPIP2), a slowly metabolized IP3 analog, the frequency of oscillations initially increased by 34% and declined to its original level within approximately 6 min. Both IP3 and GPIP2 effects can be explained by their rate of degradation: the half-life of IP3, which is a few seconds, can account for the lack of influence of IP3 photorelease on the frequency, whereas the slower metabolism of GPIP2 allowed a transient acceleration of the oscillations. The phase shift introduced by IP3 is likely the result of the brief elevatio...Continue Reading

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Citations

Feb 12, 2004·Biophysical Chemistry·Ann Zahle LarsenUrsula Kummer
Mar 23, 2011·Cold Spring Harbor Perspectives in Biology·Geneviève DupontJames W Putney
Oct 5, 2010·HFSP Journal·Geneviève Dupont, Huguette Croisier
Apr 10, 2014·Biochimica Et Biophysica Acta·Doris HöglingerCarsten Schultz
Sep 8, 2010·Mathematical Biosciences·Weijiu LiuJingvoon Chen

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