Unique Pharmacological Interactions of Taurine and Chelerythrine in the Retina
The effects of taurine and chelerythrine (CHT) on ATP-dependent calcium uptake and the phosphorylation of the ~20 kDa phosphoprotein in the retina were compared. In the absence of the CHT, taurine stimulated ATP-dependent calcium uptake and attenuated the phosphorylation of the ~20 kDa phosphoprotein. On the other hand, CHT produced the opposite results in the absence of taurine. When the two agents were used simultaneously, it was found that CHT non-competitively inhibited the action of taurine to stimulate calcium uptake, while taurine non-competitively inhibited the action of CHT to stimulate the phosphorylation of the ~20 kDa phosphoprotein. The data present an unusual pharmacological mechanism for controlling the signal transduction pathway involving the two distinct cellular processes being studied. Given the unique data, a control system is proposed in which the function of the ~20 kDa phosphoprotein is linked to the stimulation of ATP-dependent calcium uptake.
KeywordsCalcium Uptake Okadaic Acid Taurine Depletion Chelerythrine Chloride Benzophenanthridine Alkaloid
Unable to display preview. Download preview PDF.
- 11.Lombardini, J.B., 1993, The inhibitory effects of taurine on protein phosphorylation: comparison of various characteristics of the taurine-affected phosphoproteins present in rat retina, brain and heart, Adv. Exp. Med. Bio., 359:9–17.Google Scholar
- 16.Militante, J.D. and Lombardini, J.B., 1997, The effect of taurine on chelerythrine inhibition of calcium uptake and ATPase activity in the rat retina, Biochem. Pharmacol., submitted for publication.Google Scholar