Raimundo Villegas

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There are several methods by which the structure of a cell may be studied. The electron microscope makes it possible to visualize details of the ultra-structure, and to resolve these details with a resolution of 10 ~. Membranes may also be characterized in terms of the molecules which diffuse across them, leading to a resolution which may be an order of(More)
The receptor-site for the sea anemone toxin II from Anemonia sulcata (ATX) and its functional relationship with the Na+ channel were studied in plasma membrane preparations from lobster walking leg nerves. The modification of the 22Na influx by ATX was determined in membrane vesicles and in proteoliposomes prepared by reconstitution of detergent-extracted,(More)
The work of Young (1) on the anatomy of the squid nervous system revealed the existence of giant nerve fibers suitable for exploring the fundamental mechanisms of nerve function. Geren and Schmitt (2) made the first electron microscopic observations of these fibers. Our work has been concerned with the study of the functional organization of these giant(More)
The actions of grayanotoxin I, veratrine, and tetrodotoxin on the membrane potential of the Schwann cell were studied in the giant nerve fiber of the squid Sepioteuthis sepioidea. Schwann cells of intact nerve fibers and Schwann cells attached to axons cut lengthwise over several millimeters were utilized. The axon membrane potential in the intact nerve(More)
The rate constants for diffusion of THO across the red cell membrane of beef and dog, and the rate of entrance of water into the erythrocytes of these species under an osmotic pressure gradient have been measured. For water entrance into the erythrocyte by diffusion the rate constants are 0.10 +/- 0.02 msec.(-1) (beef) and 0.14 +/- 0.03 msec.(-1) (dog); the(More)