Molecular Pharmacology, Vol 8, 215-221, Copyright © 1972 by the American Society for Pharmacology and Experimental Therapeutics

Conductance Changes Produced by l-Norepinephrine on Lipid Membranes Containing a Proteolipid from the Bovine Spleen Capsule

¹ Instituto de Anatomía General y Embriología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina

A proteolipid isolated from bovine spleen capsule, with a high affinity for binding [7-³H]dl-norepinephrine, has been incorporated into artificial lipid bilayer membranes that separate two aqueous phases containing ions. To one of these phases several drugs were added, and the electrical conductance changes were recorded. The addition of l-norepinephrine produced a transient conductance change whose amplitude was related to the dose. l-Isoproterenol gave a smaller response, and d-norepinephrine had no effect. Membranes made with large amounts of phosphatidylcholine also reacted to l-norepinephrine. Since this phospholipid is absent from the proteolipid which binds norepinephrine, it is conucluded that phosphatidylcholine gives a nonspecific reaction. Several control experiments and the observation that the conductance change toward l-norepinepinephrine is blocked with phentolamine suggest that this proteolipid may play a receptor role in the spleen capsule.

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ACKNOWLEDGMENTS The authors thank Dr. M. Parisi for his helpful suggestions on the techniques for making artificial membranes, and Dr. F. Luduefia of Sterling-Winthrop for providing l-norepinephrine and l-isoproterenol.