Movement of calcium through artificial lipid membranes and the effects of ionophores

The Specificity of Ionophore A 23187 in Cation Transport across Lipid Membranes Studies with Lecithin Vesicles

“…The Egg-PC-concentration was between 2.5 x 10~3 m and 2.4 x 10~4 m in these experiments, the pH = 8. A sim ilar result has been reported before with multilayered liposomes [5]. In experiments at pH 7 and pH 6 a gradual change from the quadratic to a linear dependence o f the C a2+-efflux on cA23 was observed but not studied in detail.…”

Effect of morphine on the stimuli-induced calcium uptake into synaptosomes isolated from morphine-tolerant rats.

“…Recent findings have suggested that calcium ions play an important role in the production of analgesia and tolerance by opiates (13)(14)(15) (17,18). Chronic exposure of rats to morphine to elicit tolerance to and physical dependence on morphine did not influence the syn aptosomal calcium uptake.…”

A New Channel-forming Antibiotic from Streptomyces coelicolor A3(2) Which Requires Calcium for its Activity

“…Ionophore antibiotics which exhibit ion carrier activity include valinomycin and the actins which are monovalent cation-specific (Hladky et al, 1974) and X537A and A23187 which are calcium-specific (Hyono et al, 1975;Reed & Lardy, 1972).…”

“…Complete extraction into butanol occurred at pH 2, with reextraction into water at pH 7; slight extraction into butanol occurred at pH 4 and none at pH 7 or pH 9. Effect of CDA on membrane conductivity Certain previously described antibiotics, such as X537A and A23187 (Hyono et al, 1975;Reed & Lardy, 1972), act as ionophores capable of promoting the transport of calcium ions across membranes. We therefore tested CDA for its effect on the conductivity of artificial membranes.…”