This review covers, essentially, material published in the years 1960 and 1961. For reasons of space, work on plant cells, physicochemical studies on inanimate membranes, and most of the work on electrophysiology (even if it touched transport problems) had to be excluded. A number of symposia were held dealing wholly or partly with transport problems (25,112,173,256, 282) and several surveys were published (43, 82, 242, 331, 333, 338a). Some reviews of more restricted scope will be mentioned below. A number of con tributions to the symposia mentioned (particularly 173) also have the charac ter of reviews.Developments of special interest, in the opinion of the reviewer, include the growing amount of valuable information gained from bacteria (especially from studies on permease systems for which mutants lacking enzymes or perm eases are especially favorable), the increasing evidence for the operation of carrier systems, the approach towards better understanding of the alkali cation transport based on the study of membrane ATPase, and the growing knowledge about the types of functional membrane polarity in transporting cells, mainly of epithelia.
GENERAL ASPECTS OF MEMBRANE PASSAGEPorosity and experimental determination of pore sizes in cell membra1tes.A number of papers, mainly from Solomon's laboratory, deal with the deter mination of pore sizes in cell membranes [summaries: (288, 289)J, from meas urements of the osmotic pressure developed across a membrane permeable for a solute. From the "reflection coefficient" of Staverman (the ratio of the observed pressure to the theoretical osmotic pressure according to Van't Hoff's law) and from the molecular radius of the solute, the equivalent pore radius can be assessed by graphical methods. The equations used have been tested by Durbin (88) on collodium membranes. In the human red cell (110), measurements with nine solutes yielded an equivalent pore radius of 4.2 A, as compared to 3.5 A determined previously by means of the Pappenheimer Ussing method of comparing the rates of water movement under concentra tion and osmotic pressure gradients. In the resting axolemma of the squid axon (319, 320), a value of 4.2SA was found by Villegas & Barnola, as 1 The survey of literature pertaining to this review was concluded in December 1961 (occasional references are made to papers published in the first half of 1962). S Abbreviations used repeatedly in this review are: ADP (adenosine diphosphoric acid); ATP (adenosine triphosphoric acid); DNP (2,4-dinitrophenol). 601 Annu. Rev. Physiol. 1963.25:601-630. Downloaded from www.annualreviews.org Access provided by New York University -Bobst Library on 02/07/15. For personal use only. Quick links to online content Further ANNUAL REVIEWS