“…Over the past few years a number of review articles dealing in whole or in part with this type of transport have been published (Mitchell, 1973(Mitchell, , 1979Kotyk & Janacek, 1975;Crane, 1977;Hopfer, 1977Hopfer, , 1978Sacktor, 1977;Schultz, 1977;Eddy, 1978;Heinz, 1978;Oxender & Fox, 1978;Poole, 1978;Rosen & Kashket, 1978;Silhavy, Ferenci & Boos, 1978;Lanyi, 1979;Silverman & Turner, 1979;Ullrich, 1979;Gunn, 1980;Kabach, 1980;Lever, 1980;Murer & Kinne, 1980;West, 1980;Aronson, 1981;Borst-Pauwels, 1981;Freel & Goldner, 1981 ;Geck & Heinz, 1981 ;Njus, Knoth & Zablakian, 1981;Kanner, 1983). In the present topical review I would like to discuss several aspects of the study of such transport mechanisms which have not been extensively treated in these earlier publications.…”