Uptake of Alkaloids by Latex Vesicles and Isolated Mesophyll Vacuoles of Chelidonium ntajus (Papaveraceae)

Latex vacuoles o f Chelidonium majus (Papaveraceae) naturally sequester protoberberine and benzophenanthridine alkaloids. Isolated vesicles take up a number o f other heterologous alkaloids, such as 9,10-dihydroergocryptine, vinblastine, strychnine, nicotine, colchicine, lupanine, and 13-hydroxylupanine, with a strong preference for the indole alkaloids and for nicotine. Kinetic data clearly show that the uptake proceeds via simple diffusion and not by carrier-mediated transport. The alkaloids are concentrated in the vesicles against a concentra­ tion gradient. M gATP has no influence on alkaloid uptake. It is likely that alkaloids are trapped in the vesicles by chelidonic acid (concentration in latex 58 mM, in vesicles 661 mM) which complexes these alkaloids and thus prevents their rediffusion out o f the vesicles. Uptake o f these alkaloids by leaf protoplasts and vacuoles o f Ch. majus, by vacuoles o f suspensioncultured cells o f Lupinuspolyphyllus and by rabbit erythrocytes was studied for comparison.