Resting potential dependency on external potassium in Amphioxus muscle

The resting potential of Amphioxus muscle was determined by using an internal micropipet electrode. The effect of external potassium concentration was studied. From the curvature of the semilogarithmic plot of membrane potential versus external potassium concentration, an estimate can be made of the relative permeability of the membrane (in the resting state) to Na+ and K+. The permeability to sodium is 0.03 of the permeability to potassium. Structural features which may be responsible for this permeability difference are noted.

THE ROLE OF THE RETICULOENDOTHELIAL SYSTEM IN THE DISAPPEARANCE PATTERN OF EVAN'S BLUE DYE (T-1824) FROM CIRCULATING PLASMA

The disappearance of Evan's blue dye (T-1824) from plasma of dogs and rabbits has been followed for 4 hours in normal and T-1824 pretreated animals. One group of rabbits was pretreated with Thorotrast and the T-1824 disappearance studied for 1 hour. In both species of animals the disappearance pattern consisted of an early rapid fall in plasma dye concentration (Phase I) which was followed by a slower disappearance rate (Phase II). Phase I lasted approximately 30 minutes in dogs and slightly longer in rabbits and was curvilinear on a semilogarithmic plot. The disappearance rate during this period was markedly reduced by reticuloendothelial system (RES) blockade induced by pretreatment with T-1824 or Thorotrast. Phase II was characterized by a linear disappearance rate on semilogarithmic plot. It was more rapid in rabbits than in dogs and was unaffected in either species by RES blocking agents. The findings suggested that the RES was involved only in the first phase of T-1824 removal from plasma and that T-1824 was as effective as Thorotrast in blocking granulopexic activity of the RES.

THE ROLE OF THE RETICULOENDOTHELIAL SYSTEM IN THE DISAPPEARANCE PATTERN OF EVAN'S BLUE DYE (T-1824) FROM CIRCULATING PLASMA

The disappearance of Evan's blue dye (T-1824) from plasma of dogs and rabbits has been followed for 4 hours in normal and T-1824 pretreated animals. One group of rabbits was pretreated with Thorotrast and the T-1824 disappearance studied for 1 hour. In both species of animals the disappearance pattern consisted of an early rapid fall in plasma dye concentration (Phase I) which was followed by a slower disappearance rate (Phase II). Phase I lasted approximately 30 minutes in dogs and slightly longer in rabbits and was curvilinear on a semilogarithmic plot. The disappearance rate during this period was markedly reduced by reticuloendothelial system (RES) blockade induced by pretreatment with T-1824 or Thorotrast. Phase II was characterized by a linear disappearance rate on semilogarithmic plot. It was more rapid in rabbits than in dogs and was unaffected in either species by RES blocking agents. The findings suggested that the RES was involved only in the first phase of T-1824 removal from plasma and that T-1824 was as effective as Thorotrast in blocking granulopexic activity of the RES.