Effects of G-protein activator fluorides, protein kinase C activator phorbol ester and protein kinase inhibitor on insulin binding and hormonal imprinting of Tetrahymena.

AlCl3, BeCl2 and NaF do not influence the insulin binding of Tetrahymena immediately after treatment, but 24 h later insulin binding is decreased or increased by NaF in a dose-dependent manner, AlCl3 barely influences the binding, and BeCl2 increases it. The effect of all the three fluorides is dose-dependent. While NaF and AlF4 decrease binding at low doses and increase the binding at higher doses, BeF3 increases the insulin binding enormously. NaF does not permit insulin imprinting to be developed, AlF4 inhibits or amplifies the imprinting in a dose-dependent manner, while BeF3 allows imprinting to develop. After 24 h the protein kinase C (PKC) activator phorbol ester (PMA) increases the insulin binding to a similar degree as does the insulin imprinting itself. There was only one dose of the three tested in which PMA inhibited the development of insulin imprinting, whereas the PKC inhibitor reduced insulin binding after 24 h, but could not inhibit insulin imprinting.